Chain gear crank device to drive muscle-powered vehicle e.g. bicycles has cranks born pivoted on btoom bearing shaft, and compressible spring between crank and shaft to transmit drive momentum

摘要

The device has two cranks connected to a shaft in the bottom bracket, and offset through 180 deg . Each crank (2) is born pivoted in turning direction relative to the shaft (10) of the bottom bracket. An elastically compressible spring element (20) is located between crank and shaft, so that a drive momentum applied via the crank to the bearing shaft, is transmitted to it via the spring element. Turning movement of a crank in reverse direction is limited by a stop, and there is a torsion spring to press the crank against the stop.