Abstract: A rider propelled vehicle includes a frame having a hub portion. Each of two cranks has a crank shaft extending into the hub portion and mounted on the hub portion for rotation relative thereto independent of the other crank shaft. Both of the cranks can be rotated through a top dead center position and a bottom dead center position in which the force applied by the rider to the crank for propulsion of the vehicle is at a minimum. An output shaft extending from within the hub portion is operatively connected to a drive wheel of the vehicle for driving rotation of the drive wheel to propel the vehicle. The output shaft is mounted on the hub portion for rotation relative to the frame and the cranks. A torque transmission assembly interconnecting the output shaft with the crank shafts for transmitting torque from the crank shafts to the output shaft is contained within the frame.

Abstract: A rider propelled vehicle having a drive assembly including pedals and at least one drive wheel mounted on the chassis and operatively connected to the pedals for powering the vehicle. Left and right steering shafts are mounted forwardly of the seat generally at respective laterally opposite sides of the vehicle for pivoting about the longitudinal axes of the shafts. Left and right wheels are mounted on the left and right steering shafts, respectively, for turning about the longitudinal axes of the shafts. A steering assembly for turning the steering shafts about their respective longitudinal axes includes a steering actuator positioned for the rider to grasp and turn relative to the chassis while sitting in the seat to steer the vehicle. The steering assembly and the steering shafts are arranged in a generally inverted-U shape so that the rider's legs may extend through the inverted U to operate the pedals.

Abstract: A power assist device for use with a crank-operated drive mechanism including a pair of crank arms extending from opposite ends of a shaft mounted for rotation on a frame. The crank arms rotate the shaft about an axis with the crank arms revolving about the axis. The power assist device includes an energy storing mechanism mounted on the frame and operatively connected to the shaft for movement with the shaft. The energy storing mechanism stores energy during a first portion of a revolution of the crank arms, releases energy during a second portion of the revolution of the crank arms to assist in driving the rotation of the shaft, stores energy during a third portion of the revolution of the crank arms, and releases energy during a fourth portion of the revolution of the crank arms to assist in driving the rotation of the shaft.