Vehicle drive and power control means

Claim 1

In a tractor with wheeled axles and having a weight capable of providing a given maximum tractive effort and a hydraulic system including pump means capable of supplying hydraulic fluid at a given maximum pressure; the improvement comprising: an engine mounted on the tractor and drivingly connected to the pump means; engine control means having at least two positions, an idle position for causing the engine to run at idle speed and a full position for setting the engine to run at its rated horsepower speed; a modulated clutch driven by the engine and including hydraulic piston means for varying the amount of slip in the clutch from complete disengagement to lock-up; a valve for varying the pressure in the hydraulic piston means from substantially zero pressure at complete disengagement to full pressure at lock-up; a foot pedal connected to said valve and operable between an outward position in which the valve transmits said zero pressure and a fully depressed position in which the valve transmits full pressure; bias means for urging said pedal to its outward position and said valve to said zero pressure setting; a torque convertor of the stationary housing type driven by the modulated clutch; a transmission driven by the torque convertor; drive means connecting said transmission to at least one of the axles; and the engine being capable of driving the tractor with the modulated clutch at lock-up at said maximum tractive effort while simultaneously driving the pump means at said maximum pressure.