Patent ID: 8523145

Claim:
A jack assembly, comprising: a cylinder defining an interior; a piston having a piston head that is slideably engaged with the interior of the cylinder; an extension chamber defined between the piston head and the interior of the cylinder; and a pressure relief assembly in the piston head and defining a relief passageway in selective fluid communication with the extension chamber; the pressure relief assembly being responsive to fluid pressure in the extension chamber so that when the fluid pressure in the extension chamber exceeds a certain level the pressure relief assembly causes fluid to flow through the relief passageway, wherein the pressure relief assembly comprises a one-way valve assembly coupled to the piston for selectively permitting the fluid to flow from the extension chamber toward the relief cavity, the one-way valve assembly further comprising a valve body engaged with the piston and defining the relief passageway; a valve seat defined by the valve body; and a plug biased toward the valve seat to inhibit flow of the fluid through the relief passageway.