A device for locking a vehicle to a loading dock during a loading operation. The device includes a frame mounted on the front surface of the dock beneath a pit which houses an adjustable dockboard. A slide assembly is mounted for vertical movement on the frame, and the slide assembly includes a locking member adapted to engage an abutment on the vehicle, as the slide assembly is elevated. To raise and lower the slide assembly, a motor is mounted on the slide assembly and drives a gear that engages a rack carried by the frame. The rack is spring biased to an upper position, and on operation of the motor in one direction, the slide assembly is raised to bring the locking member into engagement with the abutment on the vehicle. Continued operation of the motor will then move the rack downwardly relative to the gear and slide assembly, and downward movement of the rack will activate a switch to cut off power to the motor. After the loading operation is completed the motor is driven in the opposite direction to lower the locking member to its storage position. The movement of the slide assembly and locking member can be tied into the operation of the lip of the dockboard in which the motor will automatically be operated to move the locking member upwardly toward the locking position when the lip is raised from its pendant position, and the motor will be operated in the reverse direction when the loading operation is completed and the lip is returned to its pendant position.

A yieldable and releasable lip lifting mechanism for a dockboard. The dockboard includes a ramp which is pivoted at its rear edge to a supporting structure, and a lip is hinged to the forward edge of the ramp and is movable between a downwardly hanging pendant position and an extended position. As the ramp is walked down from an inclined position toward a horizontal position, a lip lifting mechanism becomes operative to raise the lip and hold the lip in the extended position. A yieldable connection is incorporated in the lip lifting mechanism which enables the lip lifting mechanism to yield and fall out of supporting engagement when a substantial force is applied to the extended lip. In addition, the yieldable connection can be manually released by an operator to permit the lip to fall to its pendant position.

A loading dock board or ramp is provided having a counterbalanced, extendable lip incorporating a releasable lock mechanism. The dock board is provided with a projecting lip pivoted to the outer end of a platform and includes mechanisms for automatically raising or swinging the lip to an upwardly elevated or projected position. A counter-balance spring is included in the structure for assisting in the upward swinging movement of the lip and is structurally combined with a lip lock mechanism to maintain the lip in the projected position. This lip lock includes an automatically releasable mechanism which responds to a rearwardly directed force applied to the edge of the lip when thus elevated, to overcome to counter-balance spring and effect release of the lock thereby permitting the lip to swing by gravity to a dependent position.

An adjustable dockboard having an improved lip counterbalancing mechanism. The dockboard includes a ramp that is pivoted at its rear edge to a loading dock and is adapted to be moved from a generally horizontal cross-traffic position to an upwardly inclined position. A lip is hinged to the front edge of the ramp and can be pivoted from a pendant downwardly hanging position to a partially extended position short of its fully extended position by a lip lifting mechanism which is actuated as a consequence of the ramp moving downwardly from the inclined position to the cross traffic position. To aid in swinging the lip to the extended position, a counterbalancing spring is connected through a linkage to the lip, and the linkage provides a relative small counterbalancing force when the lip is in the pendant position, and a substantially greater counterbalancing force when the lip is in the extended position. The counterbalancing mechanism aids in pivoting the lip to the extended position, and also acts to cushion the fall of the lip to the pendant position.

A self releasing hold-down device for a dock leveler having a ramp mounted for pivotal movement about a hinge axis between a stored position and a working position includes an elongates ratchet bar engageable with a pawl mounted on a body connected to a rod which is anchored at one end to the leveler frame. One end of the rod includes a retainer and release pin member mounted thereon and whose position is adjustable by a nut threadedly engaged with the rod. A coil spring is sleeved over the rod and engageable with the retainer and release pin member. The body includes an elongated tube journalling the coil spring and a portion forming a recess for supporting the pawl. A release actuator is pivotally mounted on the body and is engageable by release pins on the retainer and release pin member in response to forces acting on the ramp to effect momentary release of the hold-down device. A manual release lever is operable, at will, to also effect release of the pawl from the ratchet bar.