Electromagnetic clutch driven steerable axle

Abstract

An electromagnetic clutch driven steerable drive axle system for a four-wheel drive vehicle, such as a front mount mower, including a rotary power source, a driven front axle, a mechanical rear axle converting power from the rotary power source into tractive power at a set of wheels attached thereto, a steering mechanism connected to the rear wheels, an electromagnetic clutch between the power source and mechanical rear axle, and a transducer which provides input representative of the turning and/or tractive power status of the mower to a microprocessor which may send current to the clutch. Having a plurality of frictional clutch disks, the clutch selectively transmits driving power to the secondary axle based on input current applied by the microprocessor. With the disks separated, the rotary power source and steerable axle are uncoupled. The rear wheels are allowed to freewheel, reducing skidding during turns in forward and reverse. Various embodiments are possible using known transducers for monitoring system parameters. The microprocessor compares these parameters to predetermine values and bases the input current to the clutch on them. The availability of four-wheel drive may be controlled by microprocessor logic and preloading of the clutch disks, either mechanically (with springs) or electromagnetically. Electrical preloading of the clutch enables vehicle torque to be intensified when additional tractive power is required.