| 摘要 |
An improved shuttle assembly for use on a load handling apparatus, the shuttle being of the type which moves between a retracted position and an extended position. The shuttle assembly has a base plate which remains stationary and includes a gear train in driving engagement with a rack on the underside of a driver plate to move the driver plate longitudinally relative to the base plate. The driver plate includes at least one gear which rotates in a normally horizontal plane and engages a rack which remains fixed relative to the base plate, so that the gear rotates in response to longitudinal movement of the driver plate. Adjacent the periphery of the gear is a roller or a cam follower which drivingly engages a channel attached to the underside of an intermediate member, thus causing the intermediate member to move relative to the driver plate at a velocity which is generally sinusoidal. A load supporting top plate is driven at a sinusoidal velocity twice that of the intermediate member by means of a chain drive having one end attached to the base plate, the other end attached to the top plate, and passing around a sprocket attached to the intermediate member. The load supporting top plate is therefore able to move between the retracted position and the extended position at a substantially greater average velocity, requiring only a simple, one-speed input, and the preferred sinusoidal velocity improves the load control capability because the load moves slowly at the beginning and end of the travel.
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