Loading dock support

Claim 1

In an adjustable dock board of the type including a ramp with front and rear edges, with the rear edge hingedly connected to an associated support structure so that the ramp may swing up and down between a relatively lowered position and a relatively elevated position, the improvement which comprises, a fluid operated support assembly for operatively supporting said ramp, said assembly comprising a cylinder member containing a quantity of operating fluid, a piston reciprocably disposed within said cylinder member and having a valve face on one side thereof, a piston rod member connected to said piston, means operatively securing one of said members to said ramp and the other of said members to said support structure, fluid passage means in said piston and terminating at one end thereof at said valve face and through which fluid may flow to control longitudinal movement of said piston within said cylinder and a flexible valve disc disposed adjacent said valve face for controlling fluid flow through said passage means, said valve face being defined by a first imaginary plane and the portion of said valve disc adjacent said passage means being defined by a second imaginary plane arranged at a preselected angle to said first imaginary plane, said valve disc being movable between a first position lying along said second plane permitting fluid flow through said passage means and a second position lying along said first plane preventing fluid flow through said passage means, said valve element normally disposed in said first position when said ramp is substantially unloaded and when a load less than a load of predetermined magnitude is applied to said ramp so that fluid may flow through said passage means, with said valve element being movable toward said second position when a load substantially equal to or in excess of said predetermined magnitude is applied to said ramp so as to prevent fluid flow through said passage means, whereby said ramp may be moved between said relatively lowered and elevated positions when said ramp is unloaded or when a load applied to said ramp is of a magnitude less than said predetermined magnitude, but said ramp will remain substantially unmoved toward either said lowered or elevated positions when a load in excess of said predetermined magnitude is applied to said ramp.