| 摘要 |
A dockboard assembly including a support means, a ramp means pivotally connected at a first end to the support means and extending to a second end, and lip means pivotally connected to the second end of the ramp means for pivotal movement between an extended cantilevered position and a pendant position. A cam is rotatably connected to the ramp means and a lift arm is pivotally connected to the support means and has a roller at the other end engaging the cam for pivoting the ramp means upwardly from any position in which the ramp means is disposed. A releasable hold-down means interconnects the support means and the ramp means for normally preventing the ramp means from moving upwardly. The hold-down means is also operable to allow the ramp means to be pivoted upwardly by the lift means and automatically allows the ramp means to pivot downwardly. A latch link is pivotally connected to the linkage with moves the lip means to an extended cantilevered position in response to rotation of the cam. The latch link is moved upwardly into positive latching engagement with an abutment pin on the ramp in response to rotation of the cam. Control pawls are pivotally connected to the lip linkage for automatically engaging the hold-down means to release the hold-down means as the lip means pivots from an extended position toward the pendent position when the ramp is below the dock and allows the hold-down means to keep the ramp locked when the lip is in the pendant position and the ramp is in any position below dock level.
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