Abstract: The specification discloses a self propelled stress testing apparatus for providing graded levels of exercise and for measuring human energy output. An adjustable frictional load calibrated in terms of patient weight and operatively coupled to a pair of translational platforms provides the exercising drag force to a flywheel against which the effort of the user is applied. Reciprocal exercising motion applied to the translational platforms is converted into rotary motion via a pair of unidirectional sprockets. Alternative embodiments employing bifilar and elastically centered slideable guide platform configurations are disclosed as well as special adaptions for use in a weightless space environment.

Abstract: The specification discloses an improved circuit for effecting a gradual change in conduction angle during "turn-on" and a rapid recovery to the quiescent "off-state" following gradual "turn-off". Both the "turn-on" and "turn-off" characteristics are achieved by using a single accumulating capacitor.

Abstract: The specification discloses a circuit which responds to a momentary contact closure to effect a gradual change from the "off" state to the "on" state, or a delayed change from the "on" state to the "off" state. In one embodiment, two interactive circuits are utilized to effect the above results from either of two remote locations. Each interactive circuit responds to a momentary contact closure at either location.

Abstract: The specification discloses a skateboard braking system which utilizes a cable actuated wedge to force a pair of friction shoes into contact with the rear wheel disks. The cable is operated by a footpedal which is attached to the front of the skateboard.