US 4,744,121 AGranted

Loading dock and hydraulic system therefor

AssigneeRite-Hite Corporation

InventorsMichael A. Swessel, Lynn O. Grunewald, Norbert Hahn

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Abstract

A hydraulic system is provided for a loading dock installation wherein the latter has a plurality of independently operable dock levelers arranged in spaced relation along the loading dock. Each leveler includes a hingedly mounted deck member or ramp and a power unit for actuating the deck member to a predetermined upwardly inclined position from a horizontal cross-traffic position. The hydraulic system is provided with a common source of pressurized hydraulic fluid which is remotely disposed relative to the dock levelers. A primary line extends from the common source to each leveler. An adjustable control valve is provided for each leveler and includes a first port which is adapted to communicate with the primary line; a second port which is adapted to communicate with the power unit, and a third port which is adapted to communicate with a drain line. Each control valve is adapted to normally assume a first position of adjustment wherein the second and third ports are interconnected and the first port is blocked. When the control valve is adjusted to a second position of adjustment the first and second ports are interconnected and the third port is blocked thereby causing the deck member to be actuated to the predetermined upwardly inclined position.

In a loading dock installation having a plurality of separate relatively spaced dock levelers operable independently of one another, each leveler including a hingedly mounted ramp, an extension member hingedly mounted on a peripheral segment of the ramp adjacent a front wall of the loading dock for movement between an extended position and a normally depending position, and hydraulically actuated power means associated with each ramp and the extension member connected thereto for effecting selective movement of the ramp from a substantially horizontal cross-traffic position wherein the extension member is in the normal depending position to a predetermined upwardly inclined position whereupon the extension member is hydraulically actuated to the extended position;

the improvement comprising a hydraulic system having a common source of pressurized hydraulic fluid in communication with all of said dock levelers and remotely located relative thereto;
a primary high pressure hydraulic line means extending from said source to each leveler;
and an independently adjustable control valve means for each leveler interposed said primary high pressure hydraulic line means and the power means for said leveler and associated extension member, said valve means including a primary valve having a first port communicating with said primary high pressure hydraulic line means, a second port communicating with a ramp sequence valve, the latter being adapted to communicate with the ramp power means of a selected leveler, and a third port adapted to communicate with a drain line, said control valve means normally assuming a first position of adjustment wherein said second and third ports are interconnected and said first port is blocked, each control valve means being adapted to be selectively moved independently to a second position of adjustment wherein said first and second ports are interconnected and said third port is blocked whereby the power means of the selected leveler is actuated effecting independent movement of the ramp thereof to the predetermined upwardly inclined position and movement of the extension member to an extended position when the ramp assumed a predetermined upwardly inclined position.

Abstract

Claims4