초록 ▼

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 edg

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.

대표청구항 ▼

A dockboard having an improved lip counterbalancing mechanism, comprising a supporting structure, a ramp hinged at its rear edge to the supporting structure and movable between a generally horizontal cross traffic position and an upwardly inclined position, a lip hinged to the forward edge of the ra

A dockboard having an improved lip counterbalancing mechanism, comprising a supporting structure, a ramp hinged at its rear edge to the supporting structure and movable between a generally horizontal cross traffic position and an upwardly inclined position, a lip hinged to the forward edge of the ramp and movable between a downwardly hanging pendant position and an extended position, means for moving the ramp from the horizontal position to the upwardly inclined position, and a lip counterbalancing mechanism comprising a lip engaging arm mounted for pivotal movement about said hinge axis and having a surface engageable with the underside of the lip, a first link having one end pitovally connected to said lip engaging arm at a location spaced from said hinge axis, a second link having one end pivotally connected to the opposite end of said first link at a pivot axis, the opposite end of said second link being pivotally connected to said ramp at a fixed second pivot axis, an extension spring mounted generally horizontally beneath the ramp and having a rear end connected to the ramp, a flexible member having one end connected to the forward end of the spring, a guide member mounted beneath the ramp and located forwardly of said spring to guide the flexible member in movement, the opposite end of said flexible member extending downwardly from said guide member and being connected to said first pivot axis, whereby the force of said spring acts to move said links toward an in-line position and pivot said arm forwardly to provide a counterbalancing action to aid in moving the lip to its extended position, said spring being disposed to exert a greater spring force when the lip is in the pendant position than when the lip is in the extended position, said links being disposed so that the force of the spring when the lip is in the pendant position will act through a relatively small moment arm to provide a first counterbalancing moment acting against said lip, and said links being disposed so that when the lip is moved toward the extended position the force of the spring will act through a substantially greater moment arm to provide a second counterbalancing moment substantially greater than said first counterbalancing moment.