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Tractor Differential Unit
When one drives their tractor (trailer or pick-up truck) on a road, they will often have to use the Tractor Differential Unit to control the tractor as it moves across the roadway. The Tractor Differential Unit is a piece of equipment which is located on the cab of the pick-up truck that has front and rear ends that pivot on casters. The unit lifts the front end of the tractor so that it can be driven while the rear end is left free and does not block passing traffic. There are two different types of this piece of equipment; a hydraulic one and a magnetic one. These differ from each other in that the hydraulic one can rotate the front end of the tractor and lift it in much the same way that a hydraulic elevator would work. The magnetic one requires a magnet to do this.
Each side of the Tractor Differential Unit has links l3 which are mounted on casters on either side of the tractor so that both front and rear axle links can pivot. When these links pivot, the tractor is able to move in any direction that they want. The links l3 are made out of steel so that they can withstand the tremendous force of a pick-up truck being pushed in either direction. There are two main styles of links l3; front end linking which is used on the front of the unit and rear end linking which is used on the back of the unit. These links also control the turning radius of the tractor so that it can turn at a much greater speed than it would without them.
To break it down in simple terms, the Tractor Differential Unit (TUD) allows for the control of the tractor to be moved in a certain direction. To do this, a hydraulic lift attachment pushes the front end of the tractor in that direction while the rear axle is left free. To move the tractor back in the opposite direction, a magnetic lift attachment pulls the rear axle into place. In figure 1, we have four different mechanisms that allow the control of the tractor to be changed in accordance to what is needed at the time.