Abstract: A racing system for a group of exercise machines is disclosed. The race is entirely flexible, in that each exercise unit communicates electronically with all of the other potential racing units. Any user may offer a race, accept or reject another user's race offer, or join a race during a limited countdown period. More than one race can be underway. For cost reduction, a daisy chain hookup is used, in which each unit's microprocessor has an input port receiving message flow from the output port of the preceding unit, and an output port transmitting message flow to the input port of the following unit. The racing function is controlled by the same microprocessor which is embedded in each exercise machine as the controller for that machine, receiving commands from the user and feedback from the machine.

Abstract: An exercising apparatus is disclosed which simulates stair-climbing. In order to reduce breakage problems in the force-transmitting structure between each pedal and a one-way rotating drive shaft, a pair of pulley wheels, each associated with a pair of cables, are used. Each pulley wheel rotates the drive shaft, and is pulled in one direction of rotation by a pedal-connected cable, and in the other direction of rotation by a cable connected to a return spring. Each cable on each pulley wheel reels into and out of helical grooves formed in the periphery of the pulley wheel.

Abstract: An exercise apparatus is disclosed which simulates a stair climber, and which determines the amount of user exercise by the speed of rotation of a flywheel. The speed of the flywheel is controlled to maintain the desired speed of stair climbing by a friction belt engaging the flywheel. A rotary electrical motor is moved in one direction to tighten the belt on the flywheel and in the opposite direction to loosen the belt on the flywheel. A slack sensor determines whether the motor has been moved to a limit in the belt-loosening direction. Incremental changes of motor energy are used to gradually reduce an error signal between command speed and actual speed. Pulse width modulation is used to vary the motor energy in accordance with the size of the error signal.