| 摘要 |
The vertical lift arms of a straddle trailer are equipped with toothed ratchet bars which move therewith as the lift arms elevate a load. Cooperating pivoted pawls on relatively stationary mounts are spring-biased toward locking engagement with the ratchet bars to safely lock the lift arms in elevated load-carrying positions. Pneumatic pawl operators under control of a switch in the tractor cab can withdraw the pawls from locking engagement with the toothed ratchet bars only when the load on the lift arms is relieved by the cable-hydraulic lift arm raising and lowering system of the straddle trailer. Hence, a fail-safe arrangement is provided should either the pneumatic or electrical systems of the trailer fail. The four customary lift arm locking units are synchronized to operate in unison. A load cannot be locked by the system when off-balance. The invention is applicable to either newly manufactured straddle carriers or those already in existence.
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