AGRICULTURAL TRACTOR WITH DRAFT COMPENSATING SUSPENSION

An agricultural tractor having a rear suspension with draft compensating geometry to control the compression or extension of the rear suspension in response to a draft load. The draft compensating suspension enables the tractor hitch to be mounted on the suspended frame or chassis of the tractor rather than mounting the hitch to a non-suspended beam axle or locking out the suspension during draft work. The draft load is applied to the chassis by a ground engaging implement. The tractive load and torque at the rear wheels are reacted through the side view instantaneous center of the rear suspension. The placement of the instantaneous center will determine the suspension reaction to the wheel load and torque. Locating the suspension instantaneous center on a line of 100% draft-compensation will eliminate the motion of the suspension due to the draft load. If the instantaneous center is located below the 100% draft-compensation line, the suspension will compress under a draft load. If the instantaneous center is located above the 100% draft-compensation line, the suspension will extend under a draft load. The distance between the instantaneous center and the 100% draft compensation line will determine the amount of compression or extension of the suspension.