Tractor carries more than his own weight on its trolley. The linkage between the tractor and the trolley is far away from the tractor. So, the whole weight of the trolley is on the back of the tractor. But why does not a tractor do wheelie with more weight on his behind?

To make it understandable, here are some photos I designed:

Tractor with empty trolley:

enter image description here

Tractor with weight on its trolley must be like this but it doesn't happen. enter image description here

What is the reason for that?

  • $\begingroup$ Early farm tractors were notorious for this. Back rolls were the single most common cause of fatal injuries on the farm for several decades. This usually happened when a plow caught on a root or rock and the tractor flipped over and on top of the driver. Implement connections such as the three point hitch largely solved this problem by being rigid and transferring the load forward to the axle itself. Utility tugs such as you have illustrated normally operate with wagons or other self-supporting rolling stock. Meaning there is no weight load on the tow bar. $\endgroup$
    – Phil Sweet
    Aug 25 '19 at 11:42

Because the rear wheels are larger so the hitch connection point is below the centre line of the rear axle.

However, if there is enough power then the tractor can do a wheelie anyway, have a look a tractor pulling competitions...

  • $\begingroup$ With the connection below the rear axel center-line the torque generated by the pull pushes down on the front wheels. $\endgroup$ Aug 25 '19 at 20:38
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    $\begingroup$ Just to add, Mike's answer solves the problem caused by pull. There's still an issue if the trailer is heavily loaded at the front but the relatively short horizontal offset between the tractor axle and the hitch make this less of a problem. $\endgroup$
    – Transistor
    Aug 25 '19 at 20:54

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