| 摘要 |
In a parallelogram linkage system whose swingable outer end supports a platform turnable between horizontal and vertical positions, the parallel arm has a hub to rotatably support a crank member. The companion lift arm of the linkage carries an actuator pin engaged with a cam surface of the crank member. The cam surface is disposed generally radially with respect to the hub and oppositely to a pin carried at the other side of the crank member. One end of the drive link is pivotally connected to the crank member pin with the opposite end pivotally connected to a short link whose upper end is coaxially pivotally connected at the pivot axis of the load platform. The platform mounts a stop member that is movable between active and inactive positions. In the active position, the stop member abuts the outer end of the drive link whereby upon cammed rotation of the crank member the platform is turned between horizontal and vertical positions.
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