Towing A Trailer: Why Don't These Buggies Flip Over Backward?

Discussion in 'The Perfect Line and Other Riding Myths' started by nicholastanguma, Sep 15, 2021.

  1. BikeMikeAZ

    BikeMikeAZ Been here awhile

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    There is a force acting on the hitch besides the down force of the hitch weight. That force either pulls away from the vehicle, as when accelerating, or pushes toward the vehicle, as when decelerating. Depending on where that force acts, down force can be added or removed from the front wheels in either case. In your low hitch stump scenario, the front wheels cannot lift because the pulling force is acting below the center of rotation of the tractor tires, levering the front wheels more firmly onto the ground. The rear wheels will slip when enough torque is applied to them. Hope this helps.
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  2. foxtrapper

    foxtrapper Long timer

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    Of course. :fpalm

    Sayeth the one who understands neither the question, nor my answer. :augie
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  3. Center-stand

    Center-stand Long timer

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    I have tried to be clear my opinion is you can't add down force to the front axle of a tow vehicle by placing the hitch low when the tow vehicle is moving forward under its own power.

    In fact my first entry in this particular segment was because of concern someone would lower a hitch and then find themselves in trouble, braking with a heavy load that took weight off the front wheels resulting in a loss of steering. Towing is dynamic. Don't take my word. Do some research. This thread probably does not offer the best info that is available.

    Be real careful the next time you try to pull a stump with your tractor. Maybe watch a tractor pull first.

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  4. Center-stand

    Center-stand Long timer

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    At least I'm willing to admit when something doesn't make sense.

    Utilizing a tractor with 3 point hitch connected to a plow, to make a point about whether or not you can increase down force on the front axle of a tow vehicle pulling a trailer on a ball hitch attached lower than the rear axle of the tow vehicle is probably the smartest thing you've done this week. .......... and , it doesn't make sense.

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  5. Center-stand

    Center-stand Long timer

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  6. BikeMikeAZ

    BikeMikeAZ Been here awhile

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    the tractor wheelies because the lever force from the increased hitch weight acting to unload the front tires overcomes the lever force of the pull below the tractor axle acting to load the front tires.
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  7. Center-stand

    Center-stand Long timer

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    Well, you are beginning to see the light.

    I'm no engineer, mathematician, or physicist but the only way you could lever the front tires of the tractor down would be to attach the low drawbar to a point higher than it is and pull from that higher point. (or put a jack under it) I don't know how high that point would need to be to overcome the rear wheel torque and traction and prevent a wheelie, but most likely more than a foot or so. Angle might be a critical factor, I don't know.

    Example you could lift with a winch. Or, attach to a large tree limb and try to drive away.

    I recall many years ago my father was going to cut down a very large tree. He was concerned about the way it might fall and wanted to put some encouragement in his preferred direction. We attached a long rope to a limb 15 or so feet up and then to the back of my Land Cruiser. As soon as I put tension on the rope I lost traction. We unhooked the Cruiser. He cut the tree, it fell as he wanted. I'm pretty sure had we stayed hooked to the tree and it fell in the opposite direction it would have simply thrown the Cruiser like a rag doll.

    In the tractor pull example, the sled, with increased weight, slowly becomes an immovable object and the torque of the rear wheel lifts the front of the tractor. In some cases the lifting of the front wheel is desired because it allows for increased traction. When you see counter weight extended from the front of the tractor you know the operator is trying to achieve a happy balance between applied power, traction, and controlled weight shift.

    None of this tractor/drawbar/three point hitch applies directly to pulling a trailer on a typical receiver ball hitch. Unlike the tractor pull, that only applies load while under power attempting to pull forward, a typical loaded trailer has some tongue weight. A single motorcycle on a light trailer might be less than 100 lbs. tongue weight, while a load of construction material on a utility trailer might be 300 to 500 lbs. Putting that on the extreme rear of the vehicle lifts the front.
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  8. BikeMikeAZ

    BikeMikeAZ Been here awhile

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    In looking at the tractor pull stuff, I realized I made an incorrect assumption. While the weight moves forward, it can't apply more tongue weight once the sled is already on the ground. The center of rotation for the pulling force is not around the rear axle nor around the center of mass of the vehicle. It is the point at which the rear tires contact the ground. So weight will be added to the front wheels when slowing down or going downhill, but not when pulling. I think you are right, Center-stand. My bad.
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  9. Center-stand

    Center-stand Long timer

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    :thumbup:thumb

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