| 摘要 |
An overtravel stop for a rotary shaft (12) is disclosed having first and second embodiments. In the first embodiment, braking torque for the shaft is supplied by the restriction by valve (14) of at least hydraulic fluid flowing in low pressure hydraulic fluid return line (18) from a hydraulic motor (22) which is connected to the shaft by a drive unit (24) in response to movement of a movable stop (34, 36) to a travel limit along an axial travel path to stop the hydraulic motor. In the second embodiment, braking torque for the shaft is supplied by a combination of a mechanical stop produced by the interaction of stop jaws (82, 84) which are respectively carried by an axially movable annular member (32) and a fixed stop (86) and the restriction of at least the low pressure hydraulic return fluid line (18) by a valve (14). The second embodiment achieves precise final positioning of the shaft by using the mechanical stop to establish the final shaft position and permits the load bearing capacity of the mechanical stops to be downsized as a consequence of substantial braking torque being applied by the hydraulic motor.
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