Abstract: A vehicle axle for use in a vehicle having both two-wheel drive and four-wheel drive operating modes. The vehicle axle includes a pair of flanged axle shafts interconnected through an axle differential. One of the shafts has inner and outer sections which can be selectively coupled and uncoupled through a shiftable clutch collar to obtain four-wheel drive mode of operation or two-wheel drive mode of operation, respectively. The shifting of the clutch collar is effected by a vacuum motor which is responsive to a control signal to cause the collar to shift between positions for mode selection. The vacuum motor has a flexural diaphragm whose displacements are transmitted through linkage to the clutch collar to effect its shifting. In the two-wheel drive operating mode, the outer section of the axle shaft is not coupled to the inner section and rotates freely under the influence of its associated wheel.

Abstract: A drive system for a vehicle having a set of front wheels and a set of rear wheels drivable from a source of power includes a transfer case having first and second operating states, a front drive mechanism having corresponding first and second operating states and a control system which can be actuated to change the operating mode of the vehicle drive system between a two-wheel drive mode and a four-wheel drive mode by changing the operating states of the transfer case and the drive assembly in proper sequence. The transfer case includes a conventional interaxle differential to permit general vehicle operation in the four-wheel drive mode. The transfer case also includes a chain and sprocket assembly which can be selectively engaged to control the transfer of drive torque to the front wheels. The engagement of the chain and sprocket assembly is controlled by a shiftable clutch collar within the transfer case.

Abstract: A transfer case adapted for use in a four-wheel drive vehicle having two-wheel drive and four-wheel drive operating modes. The transfer case includes an inter-axle differential which permits general vehicle operation in the four-wheel drive mode. The transfer case also includes a chain and sprocket assembly which provides selective power transfer to one of the vehicle axles, normally the front axle. In the first operating state of the transfer case the chain and sprocket assembly is engaged with the inter-axle differential to transmit the drive torque to the front axle. In a second operating state, the chain and sprocket assembly is disengaged and no drive torque is transmitted to the front axle. The transition between operating states is effected by shifting of a clutch collar within the transfer case to control the engagement of the chain and sprocket assembly. This shifting is accomplished by controlled actuation of a vacuum motor.