Control system for a vehicle with two speed rear axle and single speed front axle drive

摘要

A control system for a two-wheel/four-wheel drive vehicle having a rear axle which can be operated in a high speed mode or a low speed mode and a front axle which can be drivingly coupled to the engine power train to place or maintain the rear axle in the low speed mode when the front axle is sensed to be engaged. The control system includes several switches. A first switch is provided for sensing when the front axle is drivingly coupled to the power train. A second switch is associated with a speed selection control system of the vehicle for causing the power train to be driven in a low speed mode or a high speed mode. A third switch is coupled to the first switch and is responsive to sensing of the front axle being drivingly coupled to the power train for preventing the second switch from causing the rear axle to be driven in the high speed mode and for forcing the rear axle to be driven in the low speed mode so long as the front axle is drivingly coupled to the power train. Preferably the system also includes a fourth switch for sensing when the mode of operation of the rear axle is being changed from a low speed mode to a high speed mode and a mechanism responsive to the sensing by the fourth switch for preventing or locking out the front axle from being drivingly coupled to the power train.