| 摘要 |
A locking gear in the form of an annular, slotted cam member causes a driving member to move into locking engagement with a member to be driven automatically in response to the application of torque or positive rotation to the driving member. The driving member can be disengaged only by removing torque from the driving member and reversing the direction of rotation of the driven member without relying upon spring force for disengagement. Accordingly, the driving member is not only forcefully cammed into engagement with the member to be driven but is mechanically and positively cammed into disengagement at the will and under the full control of the operator. Thus in four-wheel drive vehicles, the wheels or members to be driven are selectively engaged by a drive gear which is slidably advanced through interengagement of cam followers on the drive gear with camming surfaces on the locking gear. In one form, the camming surfaces may be inner and outer concentric cam surfaces which cooperate to simultaneously control the axial displacement of the driving member into engagement with the member to be driven and to positively cam the driving member in a return direction away from engagement with the member to be driven when torque is no longer applied to the driving member and the member to be driven is reversed in rotation. |
