The rope in the driver's hand triggers a mechanical lift that runs off the motion of the inboard front plow wheel. When the rope was yanked, the plow lifted out of the ground, if everything was working properly. I first ran a tractor about the time (1958) that these devices were being replaced by hydraulic rams. The problem with the mechanical lift was that if the wheel was not turning, the lift would not work. If the ground were wet, sometimes the wheel would just slide along in the mud and not rotate. In that case, you were totally stuck because you could not get the plow out of the ground. Hydraulic rams were vastly superior.

Originally patented by Rush Hamilton, of Hamilton Tractor Company. The wheels were meant to aerate the soil of orchards, instead of compacting. See this article.

Looks like that right front wheel bearing is leaking quite a bit of grease!

[There are no bearings, as we shall see. - Dave]