|01-26-2012, 08:16 AM||#1|
Joined: Feb 2007
Location: Cape Town
Richard Trevithick - Steam Trailblazer Extraordinaire
Richard Trevithick 1771 – 1833
I want to write a bit of an essay about my hero Richard Trevithick. He is relatively unknown but made huge contributions to steam engineering. My focus is on the steam engines & engineering he did but I will cover the other stuff but quite briefly. If he is known at all it is probably as the maker of the first railway locomotive but he did this besides:
First powered road locomotive.
First proper steam engine.
First effective expansive steam engine. The Cornish engine.
First small self contained portable steam engines.
Early steam powered paddle boat.
First effective (?) steam powered dredgers.
Very nearly succeeded in tunnelling across the Thames in London 10 years before Brunel.
Developed a radical new boiler, the Cornish boiler, that was the basis for what followed.
Introduced the pole pump onto the Cornish mines. Most of the pumping beam engines on this trip used them.
Developed the water powered ram engine to replace waterwheels.
Developed the steam powered ram engine and a hybrid of the two engines.
Went to Peru and drained the flooded silver mines.
Was conscripted into Bolivar’s army of liberation.
Salvaged cannon and much treasure from sunken galleon in Pacific.
First white man to walk from Pacific to Caribbean across Nicaragua from Pacific to Caribbean.
Future president of Costa Rica accompanied him on that trip.
Made a steam turbine engine.
Made a very early naval screw propeller.
I will organise my writing broadly chronologically. Trevithick kept a lot of different balls in the air simultaneously but, for clarity, I am going to write about each type of machine as a group regardless of the time overlaps. I will give a summary about each group followed by pictures with numbered notes – I hope this makes it shorter and easier to follow so you know something about what the significance of the machines was before I show them in some detail. We have drawings of most of his engines so I will follow my comic book style of giving a drawing with a bit of commentary underneath.
We are very fortunate that his son Francis wrote Life of Richard Trevithick in 1872. It is a collection of some of his letters and drawings with added commentary. Pdf version is available at Gracesguide . My writing is based largely on that. Some of what I say is original so it needs to have references for my sources; Those from the primary source will be marked like [6.5] indicating [chapter6 . page5], other sources will be marked in  brackets and listed at the end of each posting. Sadly the Life of Richard Trevithick does not have page numbers; my numbering comes from printing the chapters at Grace's Guide. The longest chapter is Chapter 20 which gave 23 pages when I printed it (many of the chapters have false end of file markers so you have to print them in sections). Anyone really interested can use that as a guide to the page numbering I have given.
Postscript: Since drafting this I have got the latest book about Trevithick, The Oblivion of Richard Trevithick by Philip Hosken, president of the Trevithick Society . . Philip has done thorough research and reports that Francis was selective in what he presented, had to edit his father’s spelling but also embellished what he wrote and seems to have fabricated some of the interviews he published. Besides that he was fooled (or complicit) into publishing a supposed valedictory by Trevithick which was almost certainly written by Davies Gilbert. I have made some edits as a consequence but also let stuff that I am now suspicious of stand. Oblivion is an important contribution to what we now know about Richard Trevithick; I applaud Phil Hosken for having done all the research and putting the results before us.
3.….Timeline of his career. http://www.gracesguide.co.uk/Richard_Trevithick
EDIT: This thread is a companion to a longer thread about Stationary Steam Engines: http://advrider.com/forums/showthread.php?t=756771
tok-tokkie screwed with this post 04-22-2012 at 02:44 AM
|01-26-2012, 08:21 AM||#2|
Joined: Feb 2007
Location: Cape Town
Richard Trevithick was born in 1771 in Cornwall. His father, also Richard, was the ‘Captain’ (general manager) of Dalcoath copper and tin mine so Richard grew up to be fully conversant with everything to do with the mines and steam engines were a crucial component. Dalcoath was known as the Queen of Cornish Mines . That is an example of Francis Trevithick’s bending of the facts so as to glorify his father – Hosken points out it was his uncle John who was the mine Captain but Francis has made the substitution [p147].
This is the first steam engine that was erected at Dalcoath by Richard senior in 1775. It is a Newcomen engine, the first Watt engine in Cornwall came 5 years later. That engine was already 40 or 50 years old when senior bought it and transferred it to Dalcoath. Note the big supplementary balance beam loaded with rocks. This would be one of the engines that influenced Richard junior .
This is a section drawing of Dalcoath mine. Two pumping engines are shown, N, with their long rods going down to the pumps in the sump at the bottom. The water is raised to the adits marked 31 & 32. An adit is a sloping tunnel leading to the side of a valley or hill for the water to drain away thus avoiding the need to raise the water right to the surface. The zig zag behind the pump rods are the ladders for the miners. Much later man-engines were provided  which were basically pump rods with little platforms the men stepped onto & off at each stroke so the were moved about 10 feet (3m) each stroke. I don’t know what the little hash marks on the pump rods are, joints? They stop at the level of adit 32. The two wheels marked Q are waterwheels below ground level with connecting rods to rocking beams above ground also driving similar pumps. The ore and spoil was lifted by horse powered whims (winders) shown at O.
Richard went to school nearby at Camborne but was not stimulated or interested though he had a natural ability with mathematics. He grew up to be exceptionally big by the standards of the day, 6’ 2” tall (1.88m) (about 7” taller than average ) and of legendary strength. Two of the stories Francis recounts which have since become legend are: One story goes that when he was a mine Captain he came across the young men trying to see who could throw a sledge hammer across the yard and hit the engine-house door. He took the hammer and threw it right over the engine-house. Another one concerns a mine meeting which was followed by dinner and drinks when one quite large captain started a friendly tussle with Trevithick. Captain Dick (Trevithick’s popular nick name) picked up Captain Hodge by the waist, turned him upside down and rammed his feet against the ceiling that his shoe prints were left there as a memento to the event for all to see. But, like most big men, he was easy going, amusing and affable usually.
There is a record of him working in 1786, aged 15 years, at Dolcoath mine. Just four years later he was employed as the engineer at Eastern Stray mine . He joined Edward Bull in erecting his novel engines where the cylinder was directly above the shaft, which they claimed made them not subject to Watt’s patent claims. They built 10 such engines before 1793 when Boulton & Watt won a court case against Bull but Trevithick was not mentioned. Despite this they continued to erect further engines. He appeared as a witness for the defence in another patent case brought by Watt against Jabez Hornblower; two things resulted from this 1) Watt now knew exactly who Richard Trevithick was (previously he only really knew who his father was) and 2) Trevithick met Davies Gideon who became his technical guru. Eventually Watt managed to get an injunction served on him which prevented him from continuing to erect these engines.
In 1797 he married Jane Harvey, daughter of John Harvey who had a very significant foundry in Hayle, Cornwall where much of the mine machinery was made. Richard’s father had died earlier that year and he had been appointed to his position as Captain of Ding Dong Mine when he was 26 years old. The following year he also started using a different type of pump on his mines – ram pumps then known as pole pumps and he installed an improved Bull engine at Herland mine. He also installed two new whim (winding) engines. He was introducing significant changes at the mine but the biggest change was in one of those whim engines for it operated on an entirely different principal to a conventional Watt engine – it did not have a condenser or a rocking beam, it was something entirely new called a puffer engine because of the noise it made. I will describe those two whim engines fully in a later post.
The long biography by his son Francis has practically nothing about the man himself though we can gain some insights through his actions and reactions to events. The one quote is this [11.1]:
1.…. Wikipedia http://en.wikipedia.org/wiki/Dolcoath_mine
2.….Philip Hosken The Oblivion of Richard Trevithick http://www.trevithicksociety.com/archives/413
tok-tokkie screwed with this post 05-01-2015 at 02:42 AM Reason: added the missing references
|01-26-2012, 09:44 PM||#3|
rockin' the toaster
Joined: Jul 2007
Location: sunny SoCal
"If you want to fix it with a rock, you have to stick to stone-age technology" -Anton
"...solving the latest crisis that is preventing my Airhead from taking me to the bar." -Beater-
|01-28-2012, 10:53 AM||#4|
Joined: Feb 2007
Location: Cape Town
The world’s first real road loco was something Trevithick and some friends made as a bit of a back yard project in their spare time as an interesting and fun technical challenge. Well that is how I see it. He had the idea of a high pressure steam engines, had got informed technical opinion about it and then had three models built to prove the concept and R&D the idea. The models were progressively more refined but the time came to make a prototype to check it all out at full size. I don’t think he was looking to make a steam powered road vehicle. To me it seems he wanted to make a self-contained high pressure steam engine that avoided all of James Watt’s patents and this was an absolutely unambiguous way of doing just that. They made it, it worked well as an engine and he was delighted. It worked badly as a vehicle but what the hell that was hardly the point. Let’s go to the pub and have a celebratory drink or six. So what if the thing catches fire; it has done what I wanted now lets get on with getting them everywhere and make a fortune on the way.
The second steam driven road vehicle ran in London. It would appear that Trevithick hoped to generate orders for such carriages but he failed to gain any and the engine was removed and sold to power a iron hoop rolling mill.
Trevithick started informal work aged 15 (1786) with his first permanent job at 19 (1790) on the mines. Two year later he acted as a consulting engineer on the performance of an engine; it testifies to the esteem he was held in when he was just 21 years old [22.20]. The mine owners resented Watt’s control of the steam engines through his patent and the royalty they had to pay him. There were several attempts to avoid the patent which Watt squashed through the courts. Trevithick was involved in some of these to the extent that Watt got an injunction served against him and regarded him as his chief opponent in Cornwall. The patent would expire in 1800 but Trevithick had another scheme for legally avoiding it before then.
His idea was to make a high pressure engine without Watt’s patented condenser. He built a model to test his ideas in 1798. Watt’s man in Cornwall had made a model steam vehicle in 1786 which Trevithick is hardly likely to have known about (Trevithick was 15 then) . Trevithick made three different models all with the cylinder in the boiler. He was really looking to develop a high pressure steam non-condensing engine. That the model was made to power itself was incidental.
There is a complication in the chronology here. In Francis’ biography he claims that Trevithick sent a small high pressure engine to London with his employee Arthur Woolf in 1798 [8.4 19.10 19.13] That was 3 years before the Camborne road locomotive. Woolf was in competition with Trevithick to supply engines to the mines so he could hardly have been an employee and Trevithick would have personally supervised the installation of the first engine of this type to be sold & it would not have been far away in London. It seems to be an example of the creative writing of his son & biographer Francis .
The roads were so poor in those days that his road locos (he made two) did not gain any sales. Trevithick realised a rail locomotive stood a much better chance because of the smooth surface. However his main target for these engines was to power machinery = stationary engines. At this they were extremely successful but of little financial advantage to Trevithick.
I assume that is an inch scale on the side. The number cast on the model is not a date (see the caption to the picture); this is the model in the Science Museum.
Trevithick started thinking about high pressure steam engines without condenser. In 1798 he had this model made to test his ideas. It incorporates his essential ideas which were revolutionary.
1.….This is a real steam engine. It works by steam pressure, not atmospheric pressure as the Newcomen & Watt engines had. These three models were Trevithicks R&D (research & development) for what was to follow – the world’s first real steam engines.
2.….The cylinder is set inside the boiler. This ensures that it stays hot and that source of energy loss is avoided. (Watt achieved similar with a steam jacket.)
3.….There is, of course, no condenser. That is what Watt’s patent covered. Trevithick was avoiding that but also making a small, cheap, powerful and relatively economical engine.
4.….The piston is guided by a sliding cross head. This is a very simple form of straight line motion that can be made with simple machine tools. The big problem was machining a flat surface (no shapers or milling machines then) but this uses a rod which can be made in a common lathe. Trevithick was a very practical engineer – not a boffin like Watt. This engine dispensed with the heavy rocking beam and intricate parallel motion linkage
5.….A crank is used for the rotary motion. It was the obvious thing to use – Watt had decided to avoid it because the crank had been patented by someone else & he did not want to challenge a patent as it would be a bad precedent while his patents were being challenged.
6.….There is a flywheel. It is gear driven so it turns much faster than the crank. The flywheel smoothes out the energy pulses and speed. It carries the machine over the critical unpowered parts of the cycle. Remember that this was being done when there were no examples to look to for guidance.
7.….The valves are operated by a plug rod with tappets mounted directly onto the crosshead.
8.….The wheels imply a steam powered vehicle but Trevithick was really thinking more about a ‘portable’ engine. One that was self contained and could be moved to where it was needed, what we would now call transportable. However he did build his first road vehicle 2 years later.
He had at least three models made. This is a drawing of a later one.  In the second model a piece of heated iron was inserted to boil the water (just like in a domestic iron at that time) but this one used a spirit lamp [7.1]. It has a small safety valve on the boiler. The piston control valve is Trevithick’s favoured four way valve. The boiler was actually copper. He tested and worked on these models for two years. The crankpin is directly on the wheel with the flywheel gear driven from the wheel at a much higher speed. The amount of energy stored in a flywheel is proportional to the speed squared so spinning a small flywheel fast is the best way if the quantity of material (and therefore cost) is to be minimised.
Video of a recent model 48seconds http://www.youtube.com/watch?v=3uLm6YRuEuU
Camborne Road Locomotive 1801
This is the world’s first working vehicle, built in 1801. It is very similar to the models but does not have a flywheel. A steam powered vehicle had been made by Cugnot in 1770; it could crawl about but the boiler arrangement was so small it could not run for long .
The first road run of Trevithick’s Camborne vehicle was Christmas Eve 1801. About 7 or 8 people jumped on when Trevithick took it for the first run of about ¾ mile each way up quite a steep hill in Camborne. It went faster than walking pace up that hill.
No drawing remains of this road vehicle, this drawing was made by his son Francis who had spoken to many of the people involved. 
Some notes about it:
1.….Like the models the cylinder is let into the boiler so it does not lose heat. The flywheel has been left off – which is strange as it was used on all his later vehicles, possibly as a result of the deficiencies of this one. More probably Francis has made a mistake in his drawing. There is a replica of this loco which does have a flywheel similar to the model’s.
2.….The fire is in a tube inside the boiler (as against the usual practice then of having the fire under the boiler). The fire tube has a U bend to give a double pass with the smoke stack being beside the fire door (fire door not shown in the picture). This doubled the heat transfer area; a very significant advance and something that Trevithick was to pursue further.
3.….The working pressure was 60 psi (4 bar). There was no condenser so this engine worked purely on steam pressure without vacuum. Trevithick had already made several stationary engines similar to this engine – the boiler and engine have been combined into one assembly [6.2]. In this case the boiler has been used as the chassis also.
4.….It has a single four-way valve operated by the cross-head though it can also be operated by hand when starting the engine. The cylinder was double acting for it was able to run without a flywheel. There is a drawing of the four-way valve later.
5.….The exhaust was led into the smoke stack & ejected upwards to increase the draft. There are mechanical bellows above the engine (only shown in the side view), operated by the crosshead, blowing into the firebox. The blast from the exhaust steam was found to be so effective that the bellows were eliminated from all later high pressure engines [7.7 9.1 9.3].
6.….The exhaust steam pipe passed through the water feed pipe so it pre-heated the feed water. This you can see in the drawing. The feed water tank is marked W at the front of the engine. The feed pump is markedk between the feed tank & smoke stack so only shown in the plan view. From the pump the pipe curves around & tees into the heater section around the steam exhaust pipe.
7.….Drive is through just two wheels. Trevithick had tested that a horse drawn carriage could be driven up a hill by taking the horse out and turning the wheels by hand. Until then all vehicles had been animal drawn so they needed to make sure a vehicle could be wheel driven. Many years after this locomotives were still being made to run on geared rails even for mild inclines where friction would be more than adequate (Blenkinsop 1811).
8.….There is a safety valve; you can see the weighted lever in the end view.
9.….There was a steering mechanism which has not been shown on the drawing. With both wheels driven at the same speed the vehicle wanted to go only in a straight line.
It became known as The Puffing Devil after an old woman said Good gracious, Mr Vivian! What will be done next? I can’t compare it to anything but a walking puffing devil. It is claimed that it could run at 8 mph on the flat but it needed to wait occasionally while it regained its head of steam. The roads had gullies which caused it a lot of difficulty because the small wheels got stuck in them (& no suspension). One of those gullies was its undoing a few days later. On 28 December they set out on a long run of three miles but Andrew Vivian who was steering lost control when the steering was wrenched from his hands when the small wheels went into a gulley. Here is a description of what then happened afterwards:
A recent replica. A small flywheel has been added which was not in the conjectured drawing. I suspect it was an omission on that drawing. Here are two videos of the replica
1.….Video of a recent replica 12s http://www.youtube.com/watch?v=VTwyTH024JY
2.….Replica going up the original hill? 1m18s http://www.youtube.com/watch?v=6hsD3l4FUFY&NR=1
1.… http://en.wikipedia.org/wiki/Nicolas-Joseph_Cugnot .
2.…. The Life or Richard Trevithick Francis Trevithick. 1872. Chapter 7 Available here: http://www.gracesguide.co.uk/wiki/Li..._F._Trevithick
4.….Philip Hosken The Oblivion of Richard Trevithick p47 – 53
5.….Ibid p 181
Second Road Locomotive. London 1803
Trevithick learned from the lessons of the first vehicle. The next one had an engine made in Cornwall fitted to a carriage made in London in 1803.
1.….The wheels were much bigger to better deal with the poor roads..
2.….The steam cylinder was horizontal adding to the stability. The engine was made in Cornwall but the carriage was London sourced.
3.….A crosshead guide is far in front of the piston with the connecting rod running forewards to the crank. This is the first time a flat guide and crosshead has been used.
4.….There is a flywheel again to smooth the engine pulses.
5.….The exhaust steam was fed into a jacket around the boiler – very effective insulation [8.2].
6.….Andrew Vivian did a 10 mile trip from the base at Leather lane out to the Lords Cricket ground and back via Paddington and Islington. [8.4]
7.….These demos went on for six to eight months including a trip up Oxford Street.
8.….Despite the big wheels and mounting the passenger compartment on springs Trevithick realised that a smoother road was necessary so he turned his attention to rail engines.
9.….The chief market for these engines was not vehicles but as stationary engines and this is where most of their attention became focused.
Francis states that the cranks could be uncoupled on either side when going round a tight turn [8.2] and that it had gears for different speeds [8.2]. The replica made by Tom Brogden uses different gears to each wheel with drive to only one wheel at a time as it is not possible to steer it when both wheels are driven simultaneously (no differential) .
The actual drawing lodged with the patent. It shows two views of the London carriage at the top, below are four views of two stationary engines. Trevithick’s characteristic large thin rimmed flywheels are very evident.
A clearer version based on the patent drawing. Note how the piston rod forks around the crank R to reach the crosshead Q. This shows two wheels at the front. The actual carriage had a single front wheel ; with the wheels as drawn there will be a big turning moment each time a wheel hits a bump but that does not happen with a single wheel directly in line with the steering pivot. The replica has just the single wheel.
When the London carriage failed to generate any orders or even get a buyer the engine was taken out & used to power a metal hoop rolling machine [8.4] . It shows that these engines could be used to power just about anything and it is my belief that that was Trevithick’s primary goal. The Camborne vehicle was to satisfy a personal goal, the London carriage was intended to open a new market but failed but it was also a publicity stunt to make the engines widely known and in that it succeeded (although no press coverage of it has come to light). This engine represents the new type of small compact yet powerful engines that Trevithick had invented which he wanted to install wherever man or horse power was currently used – or water and wind power for that matter.
So our trailblazer has just made the world’s first effective engine powered vehicle. It is powered by the first proper steam engine but I will cover that aspect after I next deal with the world’s first railway locomotive in the next episode of this quite extraordinary career.
Video of a replica (with single front wheel when there should be two) 1m 48s http://www.youtube.com/watch?v=Dx_5hE4aGBQ
1.….Anthony Burton Richard Trevithick. Giant of Steam p83
2.…. The Life or Richard Trevithick Francis Trevithick. 1872. Chapter 8 Available here: http://www.gracesguide.co.uk/wiki/Li..._F._Trevithick
tok-tokkie screwed with this post 02-06-2012 at 12:23 AM
|01-29-2012, 08:02 AM||#5|
Joined: Feb 2007
Location: Cape Town
There is a bit of a mystery about the world’s first rail loco. We hear from Trevithick that it is being built in Coalbrookdale but we never hear of it running [9.1 9.8]. There is a drawing of an early Trevithick loco which is now believed to be of the Coalbrookdale loco though it is usually listed as the Penydarren loco. Probably the Coalbrookdale loco was converted to stationary use before it ever ran on rails.
The second loco was in Penydarren as a result of a fairly substantial bet between two ironmasters. Homfray had a few of Trevithick’s early puffer engines working in his steel works. There were four ironworks in the vicinity using a canal to move their product down to the harbour at Cardiff. One of the ironmasters had preferential rights to the canal so the other three built a tramline alongside the canal so that horses could draw their product to Cardiff on trams. Homfray bet his rival Cramshaw, who had the preferential rights, that a steam engine could do what a horse did and pull the load down to Cardiff. The loco was probably very similar to the Coalbrookdale one. It seems that the intention was to continue to use it after the bet more within the ironworks than on the delivery route. The problem was the loco was too heavy for the poorly supported cast iron rails so many broke. After winning the bet the loco was used as an engine in the ironworks to drive a hammer.
The success of the Penydarren loco became well known and Trevithick was asked to supply another to a coal mine near Newcastle. He supplied the drawing and went up to check on the making of it a few times. This loco was somewhat smaller and more refined than the previous two. It too was not used as a loco because the rails were wooden so it would have again been too heavy. It was instead used as an industrial engine. This illustrates the versatility of these small unit construction boiler/engines that Trevithick had developed – they could drive just about anything.
The final rail loco that Trevithick built was another attempt to gain publicity for his engines though this one seems to have been intended to gain orders for locos as against to just bring the small versatile engines to the notice of more people. Trevithick saw that political and financial power was centered on London so he seems to have decided it would be best to base himself there so as to close to the decision makers. In fact he learned the hard way that London was where the existing establishment was in control and they were positioned to thwart his efforts. The London loco was called Catch-me-who-can and was run a bit like a roller coaster – public were invited to buy a ticket for a ride. I think this loco is a masterful piece of design though it looks decidedly unspectacular. Trevithick was most disappointed by the results as there was no interest in buying it and the ticket sales did not cover expenses. Shortly afterwards he was asked to supply drawings for another engine in the North East but he was so disillusioned that he declined the request – he was definitely out of the steam vehicle business.
Trevithick made four rail locomotives. These were the world’s first ever locos. There is some confusion about them. The first was made in Coalbrookdale in 1802 but it seems it was never completed as no mention is made of it running. The second was at Penydarren in Wales. In the original Francis Trevithick book he gives this drawing:
The caption reads
There is no drawing of the Penydarren loco so Francis’ drawing must be based on the original Coalbrookdale loco. Soon afterwards a loco was made in Gateshead near Newcastle. We do have a drawing of that one:
Notice that the cylinder sticks out from the opposite end to the smoke stack, whereas on the Coalbrookdale loco they are both on the same end. For the rest the two locos are very similar. This was 1805. The next and final one was in London in 1808.
Here the cylinder sticks up vertically with the connecting rod coupled directly to the wheels (no gears and only two driven wheels) rather like the original Camborne road loco.
The owner of the ironworks at Penydarren, Samual Homfray, had several of Trevithick’s puffer engines and was a very enthusiastic supporter of Trevithick’s steam power. He bet another local ironmaster £500 that a steam engine could draw a load of iron on the horse tramway to the harbour about 10 miles away [9.3 9.8]. The loco was made for that bet, the usual story is that Trevithick cobbled the loco together by taking the engine from a steam hammer and mounting it of wheels just to win the bet. I have read the chapter carefully and wonder if that is true. Remember he had previously made the Coalbrookdale loco and that was purpose built – the axles fitted directly into bosses cast as part of the boiler (typical elegant Trevithick integrated minimalist and effective unit construction). There are statements by the man who helped build it that it was purpose built for the bet with the intention that it would continue as a loco afterwards but the cast iron rails broke under its weight so it was only then that it was decided to use it as a stationary engine to drive a hammer [20.6]. It seems the world’s first functional loco was built to win a wager but that it was always intended that it would continue as a working loco – that is my reading of the chapter about it.
1.….Cylinder 8.25” diameter x 4’ 6” stroke. Weight 5 tons.
2.….The fire box is inside the boiler and the fire tube is U shaped so the smokestack is alongside the fire box. I will discuss the design features of his high pressure engines in a post about the stationary puffer engines.
3.….Exhaust steam led to nozzle blasting up the smoke stack causing a forced draft in the boiler. The improvement to the fire when the loco was in motion was very apparent [9.1 9.2]. This was a fundamental feature of all steam locos but Trevithick had included it from the start. It is clearly seen on the last loco. Credit for this is regularly given to others; for example 1813 Encyclopedia Britannica claims it as a Stephenson invention , Wikipedia is correct .
4.….On the initial run down the rail line to win the bet 5 wagons with a total of 10 tons of iron and 70 men for the joyride did the trip in 4 hours. The train ran at 5mph but had to stop to clear the track & overhanging branches. The total load pulled was about 25 tons; Trevithick believed the loco could have pulled 40 tons. [9.3 9.4 18.3]
5.….The engine has Trevithick’s trademark large elegant thin rimmed flywheel and simple rod guided crosshead straight line motion. There are two ways of making a flywheel that is effective yet uses little material – high speed and small diameter or large diameter thin rim at low speed (thin spokes). Trevithick used both methods and never made the mistake of doing it the other way round (road loco & rail loco for example). He seems to have had an instinctive understanding of sound engineering principles in everything he did.
6.….All four wheels are driven. Trevithick did tests on a horse carriage before making his first road loco to see if a vehicle can be driven by turning the wheels – all vehicles before that were animal drawn so the wheels simply rolled along. What the actual driving power of iron wheels on smooth iron rails would be was unknown so he plays it safe and drives all four wheels.
7.….There are two replicas of this loco. The one at Coalbrookdale which I saw in action was built by the apprentices at GKN Sanky to drawings supplied by the Science Museum. It is just as in the drawing. I have included a link to a video of it. The second replica is at Swansea in Wales. On it the cylinder has been moved to the opposite end. This is because it is very dangerous to stoke the boiler with the crosshead reciprocating just above the fire door. The Gateshead loco has the fire grate and cylinder at opposite ends and it is supposed that the Penydarren loco would have been like that too. I have linked a video of the Swansea loco too.
Another print of the Science Museum drawing. Llewellyn is a Welsh name which is a bit strange as this is said to be the Coalbrookdale engine which is in Shropshire. I don’t know the history of the drawing. The original drawing was in the National Railway Museum in York in 1955 .
Note the flanges on the rail and flat wheels on the loco. With rails like this an ordinary cart could be used & it would be able to also run off the rails. Cylinder and fire grate at same end so it is what the Science Museum believe to be the Coalbrookdale loco.
Here is Trevithick’s own description of the test in a letter to his friend and consultant Davies Gilbert.
That is the Coalbrookdale replica (I think). My pictures of it were really poor.
This picture of the rails shows you why they broke. The track was for mule drawn wagons. The loco was built to win a wager. It is very sad that Trevithick did not enter into a partnership with Homfray; he had 2/5 of the shares in the patent [9.6 10.4]. Mathew Bolton looked after the administration and marketing aspects of their business leaving Watt to concentrate where his aptitude lay = the technicalities and manufacturing difficulties. Trevithick never chose such a partner but he took on a few very unsuitable ones who did not match his real needs which resulted in him never being a wealthy man – quite the contrary as he died in debt.
1.….There is a replica at Coalbrookdale which I went especially to see and found it under steam. It was built as a project by apprentices at GKN Sankey to drawings supplied by the Science Museum in London. I took a video of it but there already is a very good one on YouTube 1m 3s: http://www.youtube.com/watch?v=pLJaboxC3Do&NR=1
2.….There is a second replica in Swansea : http://www.youtube.com/watch?v=nZCfX...eature=related
4.…. The Life or Richard Trevithick Francis Trevithick. 1872. Chapter 9 Available here: http://www.gracesguide.co.uk/wiki/Li..._F._Trevithick
tok-tokkie screwed with this post 02-06-2012 at 12:29 AM
|01-29-2012, 08:06 AM||#6|
Joined: Feb 2007
Location: Cape Town
Newcastle Loco 1805
News of the Penydaran engine spread and Trevithick was asked for drawings so another could be built for a colliery near Newcastle [9.9]. These were sent to his agent up there, John Whitfield, at Gateshead. The engine was certainly built but the rails were wooden so it was used as a stationary engine and probably never actually ran on the track. Trevithick went up there several times during the construction. The cylinder was at the opposite end of the engine to the fire grate leaving much more space for the stoker/driver. The flywheel was right next to the driver – if you have watched the videos you see the driver needs to turn the engine off TDC or BDC when it is stopped; now he could do so from his operating platform. They set the loco going forward or reverse by swinging the flywheel by hand – you can see it in the linked video. The wheels were flanged as the wooden rails were flat – anticipating what was to be the standard for all subsequent trains. (Clearly the horse drawn wagons must also have been flanged). This engine was smaller and better built than the Penydarren loco [9.11].
So the first railway engine to be built in the north of England was to drawings supplied by Trevithick and his agent supervised the making of it locally in Gateshead in 1805.
There is a corollary to this Newcastle loco. Robert Stephenson is believed by many people to be the inventor of the loco with the Rocket. That is nonsense of course. His father George was in charge of the building of the first public railway, the Stockton and Darlington. The locomotives for it were built in the family works run by his young son (20) Robert in Newcastle in 1825 No 1 Locomotion was the design. Robert then went to work on the gold mines in Columbia in South America for three years . Robert returned in time to again take charge at the Newcastle railway works where they built Rocket for the Rainhill Trials which were held to select the loco for the railway on the other side of England (from Liverpool to Manchester). Rocket was the winner. That was 25 years after the Penydarren loco. The Stockton and Darlington railway is in the vicinity of Newcastle, the same place as this third loco of Trevithick was built. Trevithick had met George Stephenson at that time and, Francis claims, often sat with young Robert on his knee while talking to George. The dates fit; in 1805 Trevithick would have been 34 years old & Robert Stephenson 2 & his father, George 24. After Trevithick left Peru he went to Costa Rica. To return to England he decided to rather walk across to the Caribbean coast as against sailing round Cape Horn. When he arrived at Cartegena in Columbia after the crossing he was penniless but bumped into Robert Stephenson there. Apparently there was for some unknown reason tension between them, however Robert gave Richard £50 to help him on his way. This was 1827, so after the No 1 Locomotion but before Rocket. So the true inventor of the locomotive was assisted by the man who is popularly believed to be the inventor in far off Columbia two years before the Rocket won the trial. Life is stranger than fiction at times.
2.…. Excellent chronology of locos before 1825 = Rocket http://www.locos-in-profile.co.uk/Ar...os/early5.html
Catch-me-who-can, London. 1808
In another attempt to get interest in his locomotives Trevithick had an even simpler one made. It was set up on a circular track in London close to Euston Square.
The public were charged to enter the enclosure and could go for a ride in the carriage if they dared. It ran for two or three months then the track broke. Note that it draws an ordinary open horse carriage. Since both wheels are again driven they would turn together at the same speed – just what is not needed for a circular track. Today the wheels of locos & wagons are tapered so, when going round a bend, the rolling radius of the wheels adjusts as the loco shifts to the outside of the curve . Note that the rails are on sleepers; this was the first time they were used (look at the photo of the Merthur Tydfil rails on stone blocks; that was how it had been done) [9.15]. An incidental bit of common sense engineering by Trevithick that has become the norm.
This picture of the loco has been simplified. The piston is again vertical as in the original Camborne road vehicle. The wheel is connected by the connecting rod directly to the crosshead and there flywheel has again been dispensed with.
A similar engine was also used on some dredgers that Trevithick had operating on the Thames. The drive wheel was replaced by a sprocket and large flywheel. Note that this boiler has wooden heat insulation fitted. The engine has Trevithick’s favoured simple four-way valve.
A replica has been made proving that the flywheel was not required. To me this is a masterpiece of engineering where the solution to the problem has been provided using just the very barest of essentials. Very elegant and absolutely minimal. The thing that I most admire about Richard Trevithick are his lovely neat designs.
So our Trailblazer has led the way for steam rail locomotives. So good was his design the Gateshead loco would probably have performed acceptably at the Rainhill trials almost 25 years later. Wikepedia claims that John Blenkinsopp designed the first practical railway locomotive in 1812 but it used gear teeth on the rails rather than trust to friction as Trevithick had done 7 years previously (To be fair: Blenkinsopp was looking for maximum traction with minimum engine weight hence the gears).
He blazed the way showing what was possible but suffered because his locos revealed the limitations of the rails. The demand was there but Trevithick was away in South America when things were ripe so he missed out. But anyway he was disillusioned with rail locos and had moved on to other challenges which he found stimulating. For it was intellectual stimulation in the form of mechanical challenges that attracted him. Next we will discuss things with a water theme including, naturally, steam powered boats.
tok-tokkie screwed with this post 12-15-2014 at 06:18 AM
|01-31-2012, 06:40 AM||#7|
Joined: Feb 2007
Location: Cape Town
Thames and Marine Related Stuff
A posting about things with a marine theme. Trevithick dug a tunnel under the Thames, made steam powered boats, raised a sunken boat and salvaged treasure in the Pacific using a diving bell.
Trevithick got quite involved in applying his engines for use on the Thames. He was involved in removing a big rock in the harbour & then, when the London loco into which he had invested his available funds failed to generate an income he needed a job & was taken on to drive a small tunnel under the Thames – a simple mining job he thought and something he was well experienced to do. He very nearly succeeded in getting right across but the investors were uninformed and indecisive and took poor advice so it failed though Trevithick contributed to the problems.
Paddle Boat 1804
In 1804 he had the idea of making a steam powered boat, fill it with explosives and send it into the French naval port of Boulogne [15.1]. (England & France were at war at the time.) He tested his idea by fitting an engine to a 60 ton barge at Coalbrookdale. Paddle wheels each side with 6 paddles about 2’ wide x 14” deep drove it at 7 mph. Steam powered boats had been done in America in 1787 and Britain in 1788 so Trevithick was not the first but the first regular steam powered vessel was the Comet on the Clyde in 1812. So he powered a boat successfully and was prepared to go across to Boulogne with the navy & set the fire boat going but the navy never went ahead with the scheme.
Boulton & Watt made a steam powered dredger in 1796 but ir was pathetic. Oliver Evans in Philadelphia made the first decent dredger in 1802 . (Oliver Evans was an outstanding steam pioneer in the USA, did similar things to Trevithick but with much more commercial success.) Before he was involved with the tunnel he had been busy dredging in the Thames. The engine was almost identical to the one used later on Catch-Me-Who-Can [11.2]. The dredgers were not steam boats, the engine only worked the bucket and chain dredging machinery, there was a clutch to protect the chain should a bucket catch on something solid and a pedal to raise & lower the chain [11.2]. Trevithick was always overly optimistic when tackling a new project convinced that he could apply an engine to solve it and he would score big time. He was expecting to make a lot of money as there was a contract for lifting ½ million tons per year at 6d (6 pennies) per ton = £12 500 per year. The stuff dredged up was then sold to sailing ships as ballast for their outward voyages. The economics were based on manual labour but the prices had been cut to the bone. He built 3 dredgers, each more powerful than the last and set to work but he found that he had overestimated their performance and he was not delivering the ballast as fast as he had contracted to. His customer was unhappy and wanted to know when he would be up to speed, he replied that he really needed an even more powerful engine and then he would comfortably fulfil the contract but he would have to charge 9d per ton! Well that was that as the market could not absob a 50% price increase. This is a typical example of his over optimistic expectation of what his engines would be able to do and the money he would be making from them .
Cylinder 14.5” bore 4’ stroke = 368mm bore x 1219mm stroke
Power 10 hp. = 7.5 kW
Chain bucket frame 28’ – 30’ long = 8.5m -9.2m long
It worked for many years dredging up mud and rocks at the East and West India Docks in London. At least two more were built, one being much bigger at 20 hp which could raise 100 tons per hour. The engine and machinery cost £1 600.
Nautical Labourer. 1808
This was to be a utility tug that would move the ships in harbour then uncouple the engine from the paddle wheels & use it to power a steam crane. It was a good example of Trevithicks’s unbounded optimism for no fires at all were permitted within the docks. So he intended using it in the river where there were plenty of boats it could work on. Now the trades union of the longshoremen (stevedores called The Society of Coal Whippers then) were so infuriated that he had to have police protection for a while. The way Francis describes this you would think that the boat was actually built but I doubt it ever was. [15.5]
In August 1807 Trevithick was employed to take over the construction of the first tunnel under the Thames (in fact the first tunnel under any river). The project had been going for about 2 years but the man in charge had failed to even get the shaft dug down to the starting level. He was to be paid £1000 when the pilot tunnel was completed or £500 if the directors called a stop before then. He brought up some skilled miners from Cornwall and progress was good initially.
It was just the pilot tunnel to determine the soil conditions, it was 5’ high x 3’ wide at the base & 2’6” at the top. It would serve as the drainage tunnel when the final tunnel was built which would either be big enough for walking people or for horse drawn carriages. The full distance was 1220’. In just four months they were already at 950’ when there was an inrush of water when the tunnel got to a band of quicksand. They dealt with that but a month later it happened again at 1040’ but so seriously they had to abandon the tunnel until they sealed the hole from above with sacks of clay. They then cleared the tunnel and started again but now using flat iron plates to support the quicksand. Under the adversity the directors argued about the next moves.
Trevithick proposed that they build a wooden coffer dam over the hole as shown in this diagram.
Then he proposed a wooden caisson that could be placed over the end of the tunnel then dig a ditch down to tunnel level. Build the final sized tunnel out of bricks or cast iron sections, backfill and move the caisson. They only had 200’ to go to reach the opposite shore. You will see that a steam crane was to be used for excavating and moving the building materials. The little drain tunnel is shown below the big two carriage tunnel. Something like this had never been done – it was done later in Detroit in 1906-09. The directors vacillated so nothing happened from December until August (1 year since Trevithick had started). He demanded £800 for what he had done but it seems he got nothing and the company failed.
The Brunels built the first tunnel under the Thames just ¾ mile upstream with a lot of difficulty taking 18 years starting 16 years after Trevithick who had almost done it in 6 months. Brunel’s tunnel flooded five times, seven men died and Brunell was bedridden for several months by it.
The final flooding was caused by Trevithick’s pride and impulsive reactions . He was to be paid £1050 (=1000 guineas) when the tunnel reached 1000’. The surveyor who was called in to verify this agreed on the distance but added that the tunnel was about 1’ out of line (=0.1%). Trevithick was incensed by this ‘criticism’ of his ability and workmanship so he went to the far end of the tunnel & pocked a rod up through the roof & up through the water where a rowing boat was to verify that the job was perfect. That caused the hole and the final flooding. It exemplifies the difficulties Trevithick caused for himself by acting irrationally and being very prickly towards those he dealt with. It runs through his life story as a theme that accompanied his brilliance that contributed to the discord of his life. )I can't find the reference for where I read that. I have searched Francis' book and find no reference to this story.)
Iron Storage Containers 1809
Trevithick went into partnership with Robert Dickinson. They took out three separate patents for a myriad of ideas. I am not impressed by ideas, I am impressed by accomplishments so will only discuss what they actually made. One was the idea of making iron storage boxes for ships. Water and other liquids were stored on wooden barrels. They realised that they could make iron rectangular boxes custom shaped to fit into ships thus dramatically increasing the volume stored and reducing the weight of the containers. Besides that water in particular would remain clean and potable for much longer. They set up a small manufacturing works at Trevithick’s house in London. Quite how many of these were made is not known [13.x]
Raising Margate Wreck. 1810
As a follow on from the iron storage vessels they got a contract to raise a sunken ship at Margate. They made two long cylindrical tanks, took them down to Margate, partially submerged them and lashed the sunken boat to them then pumped out the water and raised the sunken vessel. Then there was an argument with the owners , Trevithick said there’s your boat & the owners said yes but we need it in the harbour, Trevithick said fine but you must pay for the that as my contract was just to raise the wreck which I have done. Owners refuse and Trevithick does what he usually does which is to lose his temper and act decisively to what he regards as provocation rather than reasonably and prudently. He cuts the ropes & lets the boat sink again. He scores nothing. It is a feature of his life that he can turn a success into failure like this. He was technically brilliant but unsophisticated in everyday life skills.
These are long cylindrical steam boilers that Trevithick supplied the following year at Wheal Prosper [19.1]. I think they may have been inspired by the camel tanks used to raise the margate wreck. These boilers were 3’ diameter x 40’ long (914mm diameter x 12m long).
Screw Propeller 1812
This was idea he had in 1812. It was never tested or proven though it was made in 1815 just before he went to Peru [15.9]. It was to be a 2 turn Archimedes screw inside a tube. It was huge; 8’ 10” diameter x 4’ long (2.7m diameter x 1,2m long) inside a slightly larger tube. He also developed a reaction turbine engine a bit like a huge garden sprinkler, this was tested and worked. The screw propeller was connected by belt drive but he did not have time to sort everything out before he went to Peru though it was clear that a lot of sorting out would be needed [16.1].
Ducks feet paddles
I don’t take ideas that were not demonstrated seriously but I like this one. He proposed two vertical rods at the back of a boat made to swing back & forth by a steam engine with paddles like ducks feet on them [15.6].
In 1808 Trevithick went into partnership with Robert Dickinson. He was busy with Catch-Me-Who-Can, the Thames dredgers and also the Thames tunnel all at the same time. He had a lot of ideas and seems to have taken Dickinson on as a partner for his commercial experience that he (Dickinson) may place things on a sound footing. They entered into three patents jointly. In 1808 a patent for the ‘Nautical Labourer’ paddle tug and steam derrick . In 1809 a multi part patent for a floating dock and a whole lot of other ideas that never got any further [14.x]. In 1809 a second patent for metal tanks and boxes for storage aboard ship. None of these schemes were a success and Francis wames out that Dickinson was a charlatan who ran up all the debts [15.6]. Burton in his book casts a very different light on the matter , he believes Dickinson was an honest man who pumped in quite a bit of money but the workmen were unsupervised, unproductive and completely disorganised. No proper record of expenses was maintained and scheduled work was not completed on time. The partnership made a loss of £4000 [15.6]. Besides not earning anything for his work on the tunnel he incurred large legal debts from patent law proceedings. In 1810 everything belonging to him in London was seized for debt & he went to a debtors prison (sponging house) [15.5]. Shortly afterwards as a probable consequence he caught typhus (also known as prisoner’s disease [15.6]. Not typhoid as sometimes reported) and was desperately ill for four months then returned to Cornwall by boat to convalesce . Early the next year 1811 he and Dickinson were declared bankrupt . Trevithick claimed that the bankruptcy commission found that all the debt had been run up by Dickinson but as they were partners he too was bankrupted [20.16]. Only by 1814 was the debt discharged, mostly by Trevithick .
South America 1816 - 1827
In Peru he made a diving bell which he used to salvage a lot of stuff from a wreck. He tried to get a licence to use it for pearl fishing which was an excellent idea but the licence never came through. He owned a pretty decent sea going vessel which he sailed up to Costa Rica in. I will give more details about these exploits when we get to that stage of his career.
3.….Graces Guide summary of Richard Trevithick http://www.gracesguide.co.uk/Richard_Trevithick
That covers his various nautical themed endeavours and starts to show the shortcommings in his character which caused him a lot of hardship.
tok-tokkie screwed with this post 02-06-2012 at 12:42 AM
|01-31-2012, 12:10 PM||#8|
Joined: Mar 2004
Location: Memphis, Motorcycle Purgatory
thanks for taking the time to do this.
God. Family. Motorcycles. Guns. Music. Books. Dogs. Beer. Baseball. Work. That about covers it.
|02-01-2012, 07:52 AM||#9|
Joined: Feb 2007
Location: Cape Town
We now come to the first of the three really great contributions Trevithick made to steam power. These are the first real steam engines.
A puffer engine is worked by high pressure steam only- it has no condenser. It was an early idea of Trevithick’s, he asked his adviser, Davies Gilbert (who was to become the President of the Royal Society ), what the effect would be if he dispensed with a condenser and just used high pressure steam exhausting directly to atmosphere. I, of course, answered at once that the loss of power would be one atmosphere….I never saw a man more delighted..[4.3]
Since the force on a piston is directly proportional to the pressure acting on it; by using steam at 4 bar (60psi) as against 1 bar gave an engine 75% smaller than a Watt style beam engine of the same power. Since power is also proportional to the number of power strokes per minute these little engines are even more powerful because of their much higher speeds.
These were the world’s first proper steam engines. They are the first of the five major contributions that Captain Dick gave the world (rest to follow).
Trevithick was keen to get them working in all sorts of new applications. I think his making of road & rail locomotives with these engines was more for fun and publicity rather than looking to vehicles as the market for his engines. The advantage of the puffer engine was their small size, cheapness and good power – small self-contained engines suited to applications undreamed of for a beam engine. They were not about efficiency, they were all about convenience and versatility.
The chronology of the puffer engines is a bit obscure. We know the third model (shown in the road vehicle post) was made in 1798 and Francis claims that a high pressure engine was sent to London with Arthur Woolf in 1798 which was so small it was carried in a cart [6.1 19.13]. The Camborne road loco ran at the end of 1801 to be followed by the patent the next year and a demonstration of the first puffer pumping engine at Coalbrookdale [9.1 20.3]. To have sent one of these engines to a customer before patenting it would have rendered the patent useless so I suspect the 1798 date & that it was Arthur Woolf who was in Trevithick’s employ is an example of the ‘creative’ writing of Francis Trevithick. The Stray Park Whim would be unlikely to use a haystack boiler if Trevithick was already using his breeches boiler 2 years previously in the London engine.
First I will show the engines then discuss what was achieved and the consequences.
Stray Park Whim 1800
Between 1800 and 1802 Trevithick erected two steam whim (winding) engines at Stray Park Mine. The first was a beam condensing engine that later worked at Camborne Vean Mine from 1832. The second was a horizontal non-condensing — or puffer — engine that was controlled with a four-way stopcock and had a horizontal cylinder set into the boiler. [6.2] The engines were known as puffers because of the sound of their exhaust.
This diagram of Trevithick’s high pressure engine comes from Farey’s volume 2 which I can’t find in Google Books (part 1 is there) and the diagram says ‘unpublished’. In fact the book was eventually published in 1971 though I have not seen it. This engine is much more powerful than his small portable engines so there are significant differences. I was initially very sceptical about this drawing as it is so very different from all his other engines but I now think it was a very early attempt at making a full sized high pressure puffer engine while he was busy making the Camborne road loco in his spare time to a much more adventurous design as his personal R&D for the concept.
1.….A haystack boiler. Trevithick used this globular shape on his initial high pressure boilers.[20.4 20.13 20.22]
2.….A full crankshaft. He used a single sided crank on his other engines.
3.….Flat sliding crosshead. He did use it on his London carriage but I was suspicious as it is a difficult thing to make compared to the rod guided crossheads he used afterwards.
4.….We have this account by William Pooley talking about the first whims, ‘Trevithick’s boiler was like a cast-iron cylinder, with the fire-door in one end and the steam-cylinder in the other end’ Trevithick made two different whims so that probably refers to the other one. [6.1]
5.….The four-way valve. Shown in the detailed drawing turned through 90° which reverses the steam flow to the cylinder. It was Trevithick’s preferred valve gear for his puffer engines. Very simple and easy to make in contrast to the poppet valves of a beam engine.
6.….What is particularly interesting is the valve below the four-way valve. That is the steam supply. By turning it 90° the steam supply was cut off giving expansive working while leaving the exhaust open as required. The diagram does not show a linkage to the cut-off valve. We know that Trevithick became well aware of the advantage of expansive working but it is unlikely he used it on this early engine. It would be a simple throttle valve adjusted by hand to stop and start the whim and control the speed.
Tredegar Puddling Mill 1801
This is a drawing made in 1854 [9.14] of the puddling engine at Tredeger in Wales ( puddling was the process for making steel). Trevithick sold several high pressure engines in Wales, the first was to Samuel Pomfray at Penydarren in Merthyr Tydfil.
1.….It has the Grasshopper straight line motion – an elegant variation on the parallel motion with many fewer parts.
2.…. The cylinder is not sunk into the boiler but cast as part of the end plate – a sign of the independence of the makers from Trevithick.
3.….Most of the ancilliary stuff like valves and pumps have been omitted from this drawing – it was made many years after the engine.
Cylinder 2’4” bore x 6’ stroke = 711mm bore x 1.828mm stroke
Boiler 6’ 9” diameter x 20’ long (boiler shortened in drawing) = 2m diameter x 6m long[10.6]
Dredger Engine 1803
An engine very similar to that of the London loco Catch me who can was used to power the bucket chain on the first of the Thames dredgers. The actual engine of that loco ended up being used to power an iron rolling mill. The various locomotive engines were very similar to the many puffer engines that were made. It worked for many years dredging up mud and rocks at the East and West India Docks in London. At least two more were built, one being much bigger at 20 hp which could raise 100 tons per hour. The engine and machinery cost £1 600.
Cylinder 14.5” bore 4’ stroke = 368mm bore x 1219mm stroke
Power 10 hp. = 7.5 kW
Boiler 4’10” diameter x 8’ long = 1473mm diameter x 2.438m long
All up weight 8 – 10 tons = 8 – 10 tonnes
Chain bucket frame 28’ – 30’ long = 8.5m – 9.1m long [11.1]
Science Museum Engine 1806
This is what the science Museum says about this particular engine.
Here you can see the water pre-heating very clearly. The water pump is in the foreground operated by the long rod dropping down from the rocking lever above. The water supply to the pump is not shown. The output goes up & flows through the larger pipe and then out and down to enter the boiler as you can see. Inside the big horizontal pipe is the exhaust pipe from the cylinder going to the smoke stack so the exhaust steam heats the feedwater. Just one of the nice little touches from Captain Dick as Trevithick was popularly known to his workers who held him in great regard..
Here you can see the fire door at bottom left so the fire passes down the boiler, turns at the far end then returns again through the water before exiting into the smoke stack. This is trademark Trevithick work. I had not initially realised that Trevithick had gone through an intermediary stage of using spherical (globular) boilers which is partly why I was so suspicious of Farey’s drawing of the Stray Park whim engine – it did not have his trademark boiler. That lovely big and thin flywheel with the simplest of balance weights is another Trevithick trademark. Just reduce everything to its essential – a function determines the form designer, not a stylist but his designs are classics.
tok-tokkie screwed with this post 02-06-2012 at 12:57 AM
|02-01-2012, 07:58 AM||#10|
Joined: Feb 2007
Location: Cape Town
Other Small Engines
This is one of the engines in the 1802 patent. It is a strange engine. The lower drawing is the side view. The flywheel is horizontal with the connecting rod above it. The whole boiler and engine are mounted on pintle bearings so the engine oscillates as it drives the flywheel. The piston rod is extended to the crankpin, there is no crosshead and articulated connecting rod. It is a sugar crushing mill with three gear driven vertical crushing rollers below the flywheel and gears. There is an amusing story attached to these sugar mills. The Spanish, who had sugar plantations in the Caribbean where water was scarce, were concerned about the amount of water used by a steam engine. Trevithick had just the answer to that problem; fill their boilers with the juice from the sugar cane, it would boil to give the steam for the engine while it concentrated the juice!
The other engine shown in the 1802 patent. This engine is double acting with a four way valve. There is a big cam with a big roller follower for operating the valve in place of the usual eccentric. I can’t figure out why the cam has two lobes per revolution – for expansive working perhaps? The boiler is spherical with external fire underneath it. It is one of the examples of his globular boilers that I initially missed.
Graces Guide has pictures of two other small engines that are not mentioned by Francis.
1813 high pressure engine built into factory for rolling mill I would say. Condensing judging by the deep sump. Rastrick was someone Trevithick had a very relaxed working relationship with. He did not require fully detailed instructions and Trevithick had confidence in his judgement & that the resulting engine would be perfectly acceptable. His brother in law, Harvey, had a great engine building firm in Cornwall but demanded absolutely detailed drawings for every single component. Besides that Trevithick would have to also endure Harvey’s opinion of what he should be doing which rubbed Trevithick up the wrong way so he chose to rather work with Rastrick. It was this reaction to well intended advice which Trevithick took as personal criticism and reacted quite violently to that was to cause much of his problems – like the Thames tunnel flooding.
I can really appreciate why Trevithick was comfortable with Rastrick’s work.
1.…. On a steamboat you need to keep the weight low as that enhances the stability of the boat. Rastrick has done it really well by setting the bottom of the flywheel level with the bottom of the boiler.
2.….The centreline of the cylinder must be in line with the center of the flywheel so it has been moved out of the boiler and angled.
3.…. Long connecting rod means less angularity and more direct force paths. The cylinder is mounted ‘backwards’ so the piston rod points away from the flywheel with a crosshead and long connecting rod back to the crank.
4.….Note that the balance weight is opposite the crank in this diagram. On the agricultural engines (next post) the weight is on the same side as the crank.
The puffer engines started with the three models 1798. We know that in 1800 he built the Stray Park whim engine which had the old globular boiler with the cylinder poking out with the crosshead slide, crankshaft and flywheel on separate wooden frames so this was an intermediate step between the beam engines and the small unit construction puffer engines. Trevithick built another high pressure whim that year very similar in looks to a Watt beam engine except it operated on high pressure steam though it still retained the condenser so it was thermodynamically more sophisticated than the Stray Park whim though mechanically more primitive. At the end of the following year (1801) the Camborne road loco ran using a puffer engine in unit construction with the boiler. This was the advanced layout of most of the later puffer engines that were built, irrespective of what function they performed. The next year (1802) they built the London road carriage with a variation of the engine where the cylinder was horizontal. Trevithick and Vivian went to London to patent the carriages and engines. The patent drawing shows the London carriage and two different puffer engines. On the way to London they obtained an order for an engine to pump and wind a colliery [7.4]. It is clear that Trevithick saw these engines as versatile engines and not simply as power for transport. According to Francis they had erected puffer engines at Penydarren in 1800 or 1801 to drive hammers, rolls, puddling plant, furnace blast and a winding engine [10.1]. That is surprising as they were not as yet protected by patent. In 1803 he has an engine working in London for the navy turning and boring cannons [8.3] and a list or 12 engines ranging in power from 3 to 14 hp [10.2]. In a letter of 1804 to Giddy he lists engines at work in 9 places and being manufactured by various foundries in several different places. The novelty of the engine had worn off and they were now well known and ‘a great number are building at different foundries’ [17.1]. The following year (1805) Trevithick writes that there are 17 or 18 foundries building his engines [9.7]. A Mr Bill bought a portion of the patent right and he reckoned that over 100 engines had been built within the first 6 years (1808) [10.5]. The puffer engines had created a very broad market for themselves within a few years.
Part of the reason for the rapid acceptance of these novel engines was their low initial cost compared to an atmospheric beam engine. In 1803 Trevithick said he had engines totalling 700 hp on order where the buyer had to pay £12 per hp for the patent right and arrange the manufacture himself [20.4]. Trevithick anticipated that he would become a wealthy man and there was not much that he had to do besides sell the right. In 1804 he writes that a pumping engine would be £220 complete and ready to be installed whilst a winding engine would be more expensive because of the flywheel and barrel at £270; these would be little puffers with 7” cylinders [17.2]. In 1816 the price for a 4hp engine was just £105 [17.12]. Compare that to the cost of buying an worn out 45” Newcomes engine for £414 moving it into a new building & updating it including a new boiler at a total cost of £2040 25 years previously (1775) [2.2].
Trevithick never set up an engineering works so he could supply engines. He either sold the drawings and the customer arranged manufacture or he had the engines made by firms such as Hazledine. He then charged a small annual licence fee during the life of his patent – at least that was the plan. But the engines were so well known that many pirate engines were being built. Dixon in London was making 2 in about 1804 but refused to pay the licence fee because Watt’s patent had covered engines ‘driven by the force of steam only’ and that patent had expired so steam driven engines were out of patent [10.4 20.5]. The patent rights were shared 2/5 to Trevithick, 2/5 to Vivian & 1/5 to West [8.5] where Trevithick was responsible for marketing and publicity, Vivian for administration and the commercial aspects and West was to be the practical man who attended to the normal mechanical problems [10.2].
In 1804 they had earned £1250 in premiums but their expenses had been £1027 because of the legal fees in trying to enforce their patent rights [10.2]. They never did make any money from these engines. In one case they went to a Cornish mine by night and removed the engine because of the refusal to pay the royalty [6.3], Cornwall was a real Wild West style territory then where that would be understood.
Vivian was in need of money so sold his share to Samuel Homfray through an intermediary for £4000 in 1805 [20.12 10.3]. In 1807 Homfray’s share had increased to 5/10 with Trevithick’s having been halved to 2/10 [10.4]. Despite the patent bringing in little income Homfray was a keen supporter of Trevithick’s work. The pity is that he had not been the partner from the start as he was a successful businessman who would have arranged things better that they benefitted from their investment and patent rights. However it is worth noting that Boulton and Watt had a patent that ran for 31 years had spent £10 000 on legal fees and had outstanding licence fees of £40 000 at one time though, eventually, they did make fortunes. Eventually Trevithick approached the government for a grant in recognition of what his inventions had contributed to the national wealth but it was declined (two of the cotton technology inventors got such grants, Compton & Cartwright).
Trevithick was aware of the advantages of closing the steam supply at part stroke and allowing the steam to expand for the remainder. To do this required an additional valve and linkage and was only occasionally used on the puffer engines. Where there was a coal mine nearby – and that was quite often, Penydarren is a good example – there was plenty of coal that was not saleable (small pieces) so economy of coal consumption was of no significance. Homfray writes the saving in coal would be very great by working expansively, but coal is not the object here [20.7]. Trevithick found by experience at Penydarren that it was better not to use expansive working when the load was variable as in iron rolling but where the load was constant he would cut off the steam as early as ¼ stroke [17.7 20.4 20.6]. Trevithick also used the heat of the exhaust steam as process heat. One interesting example was a 10 hp engine for a leather works in 1804 where the smoke stack was led through the drying room and the exhaust steam was used to heat the vats that extracted the tannin from bark and dye from wood before heating the hot house.
These were the versatile engines that had powered the first road and rail vehicles and been used on water but it was their use as stationary engines that they made a huge difference to the world. With these puffer engines Trevithick really set the steam age going for now a small self contained power unit was available suitable for small businesses such as breweries and leather works. In 6 years they had sold more than 100 units (and there were many pirated copies besides) yet Watt only sold 496 engines in 31 years (there is not much difference in the annual sales rate but this was while the market was just developing – it took Watt 6 years before they sold a single engine).
An analogy to illustrate what these engines did. Newcomen’s engines were atmospheric engines. They worked on steam at atmospheric pressure using the vacuum created when the steam was condensed to drive the engine. If a steam engine is likened to a building then Newcomen’s design is confined to being a basement only and it can only be one story deep (1 atmosphere deep). Watt refined the idea making it more efficient and also devising a rotative variant. What Trevithick did with his puffer engines was build above ground level and he could go many storeys high (many atmospheres high). Once Watt’s patent expired he could add a basement when he wished but it was an optional extra. The real steam age was built with these above ground engines and the buildings did not need to follow the same plan. Trevithick had shown that above ground was possible and effective but it was not restricted to a rigid building plan.
This was just one of great contributions our Trailblazer of steam made. Trouble is he moved on to the next project that stimulated him. But small engines like this were used in vast numbers during the Industrial Revolution – though the engine & boiler were separated. Next I will cover his agricultural engines, a cut down cheaper version of the puffer.
EDIT: December 2014
Here is a selection of engines from the accompanying thread about stationary steam engines showing the development that flowed from Trevithick’s trailblazing puffer engines. http://advrider.com/forums/showthread.php?t=756771
What I want to show is that these engines gave rise to the real steam age. Newcomen’s beam engine design was eclipsed by this design. It was developed by many persons following on from Trevithick’s initial ideas and the variations he made on the basic design. It is a fundamentally good idea which was versatile so it could be developed in different directions to meet divergent needs.
Bolton Steam Museum, Tangye engine. You can see the line of descent of this engine directly from Trevithick’s early Stray Park whim engine of 1800.
Horizontal double acting cylinder; flat sliding crosshead; crank; flywheel and there is an additional valve below the four-way valve which could be closed to give expansive working (though I suspect it was used as a throttle valve); but Trevithick did use expansive working when an engine was used against a regular (un-fluctuating) load.
Ellenroad. Very elementary engine. I notice that it has a red painted valve on the steam supply but also a larger black valve on the exhaust. I assume the valve on the exhaust allows the piston to be locked in position by steam pressure. Note the cloth as a silencer.
Bolton, Tangye Colonial engine. A later development where the engine has been reduced to fewer components – it has been refined and simplified while making more efficient use of the materials and carrying the forces directly between the cylinder and the crankshaft. It is a feature of Trevithick’s designs of how he too naturally simplified them with the passage of time; a case in point is the wonderfully simple design of his final locomotive engine.
Crofton, Marshall inverted engine. This engine is larger than the previous ones. The operating principle is not restricted to small engines. The cylinder is now vertical. Many of Trevithick’s puffer engines were vertical.
Bolton Steam Museum, McNaught tandem compound engine, 1902, 200HP. Here we see a significant development – this engine has two cylinders in tandem, it is a compound engine (high and low pressure cylinders using the steam twice). There is also a condenser. Trevithick made a compound engine at Treskerby mine in 1815 but it was a beam engine and he never pursued the idea actively.
Bolton Steam Museum, Robey cross compound engine, 1935, 80HP (small as it is a teaching engine). It is plain to see that it is two engines side by side working the same crankshaft and flywheel. Here the high pressure cylinder is on the left; the steam is expanded a second time in the right hand cylinder and then passed to the condenser so the right hand cylinder extracts the energy of condensation too – like Trevithick’s Cornish cycle engines did.
Kew, James Simpson cross compound, 1910, 180 HP. A larger cross compound engine.
Science Museum, London, Harle Syke mill engine, 1903, 375kW, 500 HP. A single engine used to drive an entire factory. A few really large beam engines were made with the Centennial engine representing the limit at 1400HP. The two obvious advantages of dispensing with the beam is firstly the far more compact size of the engine with a corresponding reduction in cast iron needed and secondly the versatility of the design; it can have many cylinders arranged vertically , horizontally or a bit of both; compounded or not and condensing or not.
Ellenroad. 1890 rebuilt in 1916 to be a twin tandem compound engine. The biggest running mill engine in existence at 3000 HP. Tandem compound means there are two cylinders one behind the other. Twin means there are two such engines alongside each other driving the same flywheel.
Not my picture. Shows the twin compound layout. The flywheel weighs 85 tons driving 44 ropes. Picture from http://www.urbexforums.co.uk/showthr...-J21-may-2011?
Another twin tandem compound. This time a winder driver on a coal mine, Astley Green. 1912 3000 – 3500 HP.
Corliss valve gear.
Finally three different engines showing really large engines adopting different strategys.
New York 58th Street Power Station. ‘Manhattan’ engines built by Allis Chalmers in 1905. Rated at 7500HP but they ran regularly and continuously at 11 000 HP without trouble or undue wear. These were the zenith of steam engine development. There is a horizontal high pressure cylinder and a vertical low pressure cylinder. Two such engines are coupled to a single flywheel/generator.
Kelham Island Museum, Sheffield. The River Don Engine built in 1905 by Davey Brothers, 1200 HP. Here is an engine built for maximum power at a low capital cost where efficiency was not required – there is no condenser and, at maximum power the steam is not even expanded. Three big but ‘crude’ puffer engines side by side on a common crankshaft.
Source: *Chris Allen*
The Kempton Park Pump Station No 6 engine. 1929. These are engines optimised for efficiency (lowest running cost). They are just 1000 HP compared to the River Don engine at 12 000 hp yet it weighs twice as much (800 tons vs 400 tons). That illustrates beautifully what a compact but powerful engine the River Don is whereas this one is all about getting as much as possible out of the fuel. Coal consumed amounted to only about 1 and 1/4 lb per horsepower per hour, equal to the best electricity generating stations of the day.
tok-tokkie screwed with this post 12-19-2014 at 06:01 AM
|02-02-2012, 08:32 AM||#11|
Joined: Jul 2002
Location: Bay Area ~ NorCal
Another amazing thread by tok-tokkie. Thanks!
Everybody is someone else's weirdo.
|02-03-2012, 08:34 AM||#13|
Joined: Feb 2007
Location: Cape Town
I am really pleased to get some other people appreciating this guy. He is my hero, but not without his troubles like the rest of us.
|02-03-2012, 08:55 AM||#14|
Joined: Feb 2007
Location: Cape Town
Low Cost Agricultural Engines
Low Cost Agricultural Engines
The agricultural engines were a variation on the puffer. Here the aim was simplicity and cheapness. Where the puffer was about compact power with a high pressure double acting engine the agricultural engine was considerably simplified. It was a single acting engine with a simpler and much less sophisticated boiler so that an unskilled farm worker could get on with his job while the engine did the hard work. They replaced animal and people power without the need of much from the worker besides adding a little coal (or other fuel = wood, bagasse or dung?) to the fire every now and then. The engines were also relatively small and light so they could be moved from place to place where needed – no heavier than a farm cart. These engines were exported to the Caribbean and reached the States where copies were made. They were also the style of engines sent to Peru to work on the silver mines high in the Andes (14 000’).
Trevithick developed these engines when he was back in Cornwall after having typhus in London and being declared bankrupt (1810). They were one of the products of his resurgence after that low point in his life.
Trevithick developed simplified and cheaper versions of his portable engines aimed at making them applicable to much smaller tasks on farms and small businesses. This one was supplied in 1812, it drove a threshing machine.
[img] http://www.gracesguide.co.uk/images/...-Thrashing.jpg [/img]
Note the following.
1.….The connecting rod is coupled directly to the piston. This saves the expense of the straight line mechanism and crosshead. The piston is made longer so that it guides itself – it introduces the layout we are now familiar with in a modern IC engine. It is another example of Trevithick’s ability to simplify mechanism and contain costs.
2.….The engine is not double acting. This saves the costs of the neck gland & allows for a simpler valve to be used. It is required if the connecting rod is to be coupled directly to the piston.
3.….A large flywheel is fitted – required to smooth the power pulses since the engine is single acting. It is Trevithick’s trademark large wheel with elegant thin rim. Flywheel 6’ 6” diameter (2m) [17.7].
4.…. I initially though the drawing is wrong as the balancing weight should be opposite the crank. Later I realised that the cylinder is vertical so that weight helps on the unpowered downstroke & stores energy on the upstroke. I would think if it was 90° ahead of the crank it may have helped with the downstroke even more.
5.….Cylinder bore 9”. Trevithick rated it at 4 HP. It ran at 30 rpm.
6.….The price of this complete boiler and engine was £90 [18.1].
7.….It used 164 lbs of coal costing 2s 6d in 6 hours whereas feed for four horses would cost eight times as much [18.9].
8.….They typically ran at 25psi (1.8 bar) expansively with cut off as early as ¼ stroke [17.7].
9.….One man easily operated the engine and thrashing machine by himself.
The engine worked at Trewithin farm for 67 years then it was presented to the Science Museum. That is not the original boiler. Immediately this engine was seen at Hawkins farm 3 neighbours placed orders [18.2]. These engines were used to thresh corn, grind corn and saw wood. They did then what tractors regularly do today on small farms but this was entirely novel then .
Trevithick offered a 3HP engine for £63 weighing 750 kg, a larger one at £105 [18.2] and a 12hp at £210 was ordered by a sugar mill in the West Indies [18.5]. Note that horses & mules can work just 6 hours per day so if this engine run 24 hours would require 48 horses to do the same work. The cost of those mules was five time the cost of the engine in the West Indies in 1812 [18.4].
This is one of the American copies. Trevithick sent a lot of engines to the West Indies to work on the sugar plantations. From there their reputation spread to America where many knock-offs were made. One lasted about 90 years for it was exhibited in 1893 at the World Columbian Exposition in Chicago, illustrated above.  Note Trevithick’s trademark plug valve connected to the eccentric on the crankshaft and the throttle valve before it for speed and power regulation. These were really stripped down engines. The boiler is filled with water, there are no ancillaries on it like even a safety valve or water or pressure gauges. It would run for 6 hours on a filling, rated 4 horse-power using 10 lbs of coal per hour [18.3]. A farm labourer had no trouble running one as it was so simple – what is there? A little fire to add some coal to and a single valve to adjust the speed. They cost just £80 – no wonder they were a success.
This engine has a nice strong 6 spoke flywheel but I prefer the elegant large diameter thin rimmed 4 spoke flywheels of Trevithick. I much prefer his design of the counterweight – a straight line and the same thickness as the rim.
I am also amused by the tactics of a country entering into industrialisation. Copy a successful design from the leaders. I grew up when Japan was doing it in the 50s & China is doing it right now. Never knew America had been down that route. I say it with amusement; not trying to bug my readers.
A British one. Built 1811 for grain threshing & chaff cutting. The 9 engines sent to Peru (see later) were like this. It has a safety valve and feed water pump. The boiler has an internal flue – essential in Peru where fuel was scarce. Because they used wood at first so the internal firebox was too small they mounted the boiler above a fire box so the boiler was heated from below then the it passed through the internal flue.
The agricultural engine was all about making them cheap to buy and very easy to operate as they were to replace horses and mules. To do this Trevithick modified his puffer design in three significant ways showing that he was not a [i[one trick wonder[/i] but an analytical designer who produced a design appropriate to the need. So he simplified the engine from double acting to single acting giving a much simpler and reliable mechanism requiring not much maintenance. He dispensed with the crosshead, instead there was a long heavy piston driving the flywheel through a connecting rod and crank; pioneering the now familiar layout of an IC engine. He used a very simple and low cost haystack boiler with the fire outside underneath; it was to be filled but once a shift with water. There was a single throttle valve to regulate the engine speed though it was also dependent on how well the fire was maintained.
After the original £80 4hp engine for Hawkins of 1812 Trevithick standardised on a 3hp engine so that they could easily be moved in a cart [18.1 ]. These engines cost just £60 for a 2hp engine & £105 for 4hp [17.5 17.12]. Considerably larger engines were needed for the Caribbean sugar mills but simplicity and low cast was still of prime importance. An engine of 10 mule power (so 40 mules a required for 24 hours) engine cost £200 compared to £2000 for a beam engine to do the same job [18.4]. His double acting puffer engines were about three times the price; £270 for one with a 7” (178mm) cylinder in 1804 [17.2]. That sugar mill engine needed just 14 bushels (1176 lbs) of coal per 24 hour day to do what 40 mules could do [18.4 18.5]. The Spanish indicated that they could require 1000 engines in their colonies [17.1].
Trevithick saw that the engines needed to be light or on wheels so they could be moved to wherever the power was needed [15.8]. He even made a really small engine equivalent to 2 man power [15.10]
These engines were a smart variation on the puffers and demonstrate Trevithick’s ability to see what was important and then design an engine to achieve that. Next we will move on to the pumps he introduced into the mines which lead on to some very interesting water powered engines he invented. Trailblazing wherever he goes.
1.….Philip Hosken The Oblivion of Richard Trevithick p233 http://www.trevithicksociety.com/archives/413
EDIT December 2014. I am wanting to liven up this thread with some color pictures. Some pictures taken from my ‘Croc’s Guide to Stationary Steam Engines thread. We saw no single acting engines on that trip but I would like to amplify this post with some really simple engines which can be considered to be the successors to Trevithick’s absolutely minimalist Agricultural engines. The little engines shown here were used where there already was a boiler, either for process steam or to drive a large stam engine driving the process machinery. It was a simple matter of running a steam pipe to the little engines.
Manchester Museum of Science and Industry. A vertical engine by Chadwick 1869. It has the same flywheel above the cylinder as in Trevithick’s agricultural engines but the cylinder is double acting so there is no need for a balancing weight on the flywheel.
Crofton. Marshall inverted vertical engine. 5 hp = 3.7 kW This is termed an inverted vertical engine for Trevithick’s layout of his agricultural engine with the cylinder below the flywheel set the pattern and was regarded as the normal arrangement.
Another vertical engine but with a very significant variation. The steam piston is connected directly to the pump piston – they are linked by a solid connecting rod. The rod is not a straight rod – it has a banjo shape but it moves in a straight line. The flywheel crank turns within the banjo section; driven by a short articulated connecting rod pivoted at the apex of the banjo. This basic layout was much used for small pumps.
Similar banjo engine at Crofton. Has been laid down horizontally but otherwise it is almost the same. The slight difference being that the connecting rod is articulated from the pump side of the banjo in this case.
At Claymills. A common variation where the banjo section is differently shaped resulting in these being referred to as Wishbone engines. The function is the same but by bending the banjo arms out of the way of the crankshaft they can be made straighter. Functionally it is just the same as a banjo engine.
Another little ‘banjo’ engine at Claymills. In this case they have moved the connecting rod (in fact there are now two of them) outside the ‘banjo’ so the banjo bit is more of a mandolin shape.
Small pump engines like these banjo engines and other designs were made in their thousands – many to deal with the condensate from steam engines or to supply water to the boilers. Today small electric pumps are ubiquitous in industry – before electricity it was little steam pumps like these.
This is interesting. The first internal combustion engine to be marketed was by Otto & Langen 1869. This is one made by Crossleys of Manchester under licence.
It has a similar layout to Trevithick’s agricultural engine but it uses a rack and ratchet arrangement instead of a crank and connecting rod. To better appreciate it look at this video of the actual original engine, serial #1 1:20 minutes http://www.youtube.com/watch?v=09cqOUHbmBI
MOSI 1882 Developed by Bisschop in France. This is also an atmospheric gas engine but the piston is connected to the flywheel by a crank so it is no longer free. It ran much more quietly and smoothly than an Otto atmospheric gas engine but it used much more fuel. It also points the way of many simple motorcycle engines – it is air cooled with fins on the barrel which also serve as strengthening gussets. This engine is very similar in layout to Trevithick’s Agricultural engines. Vertical single-acting cylinder with crank driven flywheel overhead. Piston is heavy so that gravity assists in evening out the power pulses (it absorbs energy on the upwards power stroke and transfers it to the flywheel on the downstroke). The big difference is these engines are far less powerful making them suitable to power really small machines.
tok-tokkie screwed with this post 12-18-2014 at 06:20 AM
|02-04-2012, 04:26 AM||#15|
Joined: Feb 2007
Location: Cape Town
I have been struggeling to cut & paste from MS Word. Bendernz pm'd me with how to do it. Very much appreciated.
This was one of Trevithick’s minor contributions. Previously the mines had been pumped by lift pumps with a piston moving inside a cylinder with a leather cup seal. Trevithick changed to a pole pump (better known as a ram or force pump) where there is no leather cup seal on the piston and the cylinder can be a rough casting. These pumps were not invented by Trevithick but using them in the mines of Cornwall was his idea and he had to scale them up considerably for the job. They proved so superior that soon all the mines had converted to using them and nearly all subsequent big steam pumps were ram pumps. Mine water is gritty so not having a sliding piston seal removed a constant source of trouble.
Pumping the water out of Cornish mines is what led Newcomen to develop the steam engine and it was where Boulton & Watt found the first big market for their engines. The pumps that were used then were lift pumps
This is a lift pump; the best diagram I can find on the internet. In a lift pump the water is raised on the up stroke. A leather cup formed the seal between the piston and cylinder. Mine drainage water has a lot of grit in it so these were very problematic pumps suffering both wear and jamming [5.1].
In 1797 Trevithick had a Force (also called Pole or Plunger ) pump made and installed at Ding Dong mine followed shortly by the adjoining Wheal Markin and Wheal Providence mines [5.2]. These replaced the lift pumps but he did not invent the force pump; he merely adopted and improved an existing idea.
Simple diagram of a force pump. Also called plunger, pole or ram pump.
This is a Force pump[5.1]. b is the plunger passing through the hemp rope filled gland at the top d into the cylinder c. There are valves as in a lift pump but there is no piston seal, the plunger does not touch the cylinder. This means that the cylinder can be a rough casting, a great advantage in the days of primitive machine shops and there was no leather cup seal. These were big pumps, Wheal Druid was 10” bore x 9’ stroke (254mm bore x 3m stroke) [5.3]. The weight of the pump rod and pole had to be greater than the weight of the water column since the water was displaced (forced) upwards by that weight on the down stroke (unpowered). When these pumps were later used as civic pumps for water and sewerage big weights had to be added to the rod above the pump to develop the required force (Kew for example).
Initially there was much scepticism about these pumps when Trevithick first installed them but once they had proved themselves they rapidly became the standard pump used in Cornwall. When the beam engines were later used for pumping town water and sewerage force pumps were the norm.
Picture: Malcolm Nott (Carnkie @ Aditnow)
A picture of a fairly recent plunger-pole pump. It has two plungers feeding a common riser pipe. Trevithick had led the way to a more effective and reliable pump.
Trevithick combined a Lift and Force pumps into a single pump which gave flow on both the up and down strokes [5.1]. As a final insult he replaced the Watt patented air pumps with force pumps [19.11].
Mine Pump Layout
The pumps were arranged to lift the water in stages. To avoid lifting the water all the way to the surface a side tunnel, called an adit, was dug across to the side of a hill or valley so the water could run out there instead of at the surface.
This is a section drawing of Dalcoath mine where Trevithick grew up. Two pumping engines are shown, N, with their long rods going down to the pumps in the sump at the bottom. The water is raised to the adits marked 31 & 32. An adit is a sloping tunnel leading to the side of a valley or hill for the water to drain away thus avoiding the need to raise the water right to the surface. The zig zag behind the pump rods are the ladders for the miners. Much later man-engines were provided  which were basically pump rods with little platforms the men stepped onto & off at each stroke so the were moved about 10 feet (3m) each stroke. I don’t know what the little hash marks on the pump rods are, joints? They stop at the level of adit 32. The two wheels marked Q are waterwheels below ground level with connecting rods to rocking beams above ground also driving similar pumps. The ore and spoil was lifted by horse powered whims (winders) shown at O.
This more detailed diagram shows the shaft in two pieces on the right. Two pumps in series at the bottom lift the water to the cistern at H where there is also a working passage. The second pair of pumps in series then raises the water to the adit L (shown on both pieces). Above this there is the plain pump shaft up to the beam. Note the ladders. On later mines special man engines were introduced – little platforms on the rod for a few men to stand on with fixed platforms on the sides of the shaft so that the men could step on and off as they were raised or lowered in stages.
1.….Leawood Pumping Station. Here is a really good video of a ram pump. It lifts water from a river and discharges it into a canal alongside so there is very little pressure on the delivery side so the ram drops unusually fast. 6:26 minutes. http://www.youtube.com/watch?v=PdIgEQ-r0nU
See this thread for more details about that pump http://www.practicalmachinist.com/vb...-tools-204862/ )
2.….Kew pumping station. The Maudsley engine. Long with long introduction Watch it lift 12 tons very quickly then the slow descent as the ram falls delivering the water against the delivery pressure. 8:34 minutes. http://www.youtube.com/watch?v=eOudaWLFW0g
3.….Kew. 90” engine. Again notice how easily the pump lifts the weighted rod then it drops slowly as it delivers the water. (on the mines the pump rods were extremely heavy so they had counterbalances fitted to lessen the load on the engine and the force of the delivery stroke of the pump). http://www.youtube.com/watch?v=OP9__nQ-_YM
This was one of the minor contributions that Trevithick made. It is significant that all except 1 of the beam pumping engines we saw used force pumps – he introduced what became the standard. (That refers to the parallel thread about steam engines. http://advrider.com/forums/showthread.php?t=756771 )
tok-tokkie screwed with this post 02-04-2012 at 04:35 AM
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