Abstract: An exercise apparatus includes a bench support, and an input bar pivotally mounted on the bench and movable through a work cycle in response to forces exerted by a user. A hydraulic actuator is connected to the input bar for developing a resistive force against the movement of the bar. An adjusting mechanism enables a user to vary the resistive force. A pressure transducer senses the pressure in the hydraulic actuator which is representative of the input force exerted by a user, and a potentiometer located at the pivotal connection of the input bar on the bench measures the angle of rotation of the bar which is representative of the displacement of the bar. The force and displacement input signals are employed by a microprocessor to generate output signals to a display showing the cycle count, the input force or the work accomplished by a user during each cycle.

Abstract: A system for resiliently supporting a load at a reference height includes a hydraulic cylinder for resiliently supporting a load about a reference height and an accumulator which cooperates with the cylinder for flowing hydraulic fluid therebetween in response to varying loads imposed on the cylinder. A valve is provided for dampening the rate of fluid flowing between the cylinder and the accumulator and a metering valve coacts with the cylinder for adjusting the reference height about which the load is supported.

Abstract: Disclosed are two embodiments of a locking cylinder. In both embodiments the locking cylinder comprises a housing, a working piston, a pilot piston, and a counter balance valve to substantially smoothen the operation of the working piston, particularly when an induced pressure is applied to the working piston. In the first embodiment, the pilot piston slides as a unit, although it may be formed in two axially separate parts. In the second embodiment, the pilot piston is formed in two axially separate parts, communicating bores are formed in the two parts, a ball valve is located in the bore in one of the parts, a free floating pin is disposed in the bores between the ball valve and an abutment surface in the other part, and the ball valve is biased shut. The pin is sized to unseat the ball valve when the two parts are in contact, but the two parts are biased apart by the action of the biasing means, which is transmitted through the pin to the abutment surface.