Adjustable hydraulic load-resisting mechanisms for exercise machines

Claim 1

An exercise machine comprising: a frame; an exercise arm pivotally connected to said frame at a pivot axis; radially spaced inner and outer cylinders defining an inner chamber in the inner cylinder and an outer chamber between said cylinders; end blocks interfitting with the outer cylinder; end members interfitting with the inner cylinder and secured to respective said end blocks, and each inner cylinder having a pressure port and a return port communicating with the outer chamber via a pressure passage and a return passage, respectively, in the adjoining end block; a double-acting piston in the inner cylinder having a piston rod extending through one of the end members and the respective end block, said piston rod and other end block being pivotally connected, one to said exercise arm and the other to said frame at a location remote from said pivot axis; a respective check valve mounted on each end member for blocking flow from the inner chamber to the outer chamber through the respective return port; a respective spring-loaded flow control valve in each pressure passage; and respective adjusting means for each flow control valve for independently adjusting the spring pressure on the flow control valves.