Retractable/extendable crank using a cylindrical cam, an end cam, or a swash plate cam, and bicycle using the same

A retractable/extendable crank comprising:

• a fixed arm having an end coupled to a rotary shaft of a rotary body to transmit torque and a cam guide being in close contact with a slope of an end cam or a swash plate cam;
• a movable arm retracting and extending while longitudinally sliding in the fixed arm;
• the end cam or the swash plate cam disposed in the movable arm in an axial direction of the movable arm and having a rotary shaft and a cam body formed by cutting off at an angle an end of a pipe or a cylinder having a predetermined thickness;
• a close-contact spring having one end connected to the fixed arm and the other end fixed to the movable arm to keep the slope of the end cam or the swash plate cam and the cam guide of the fixed arm in close contact;
• a pedal composed of a pedal shaft coupled to an exposed end of the movable arm and a pedal plate coupled to the pedal shaft, the pedal plate not rotating with the pedal shaft;
• and
• a pair of bevel gears coupled to a camshaft of the end cam or swash plate cam and the pedal shaft of the pedal, respectively, and having a tooth ratio of 1:1.

A retractable/extendable crank comprising:

• a fixed arm having an end coupled to a rotary shaft of a rotary body to transmit torque,
• a boss coupled to the rotary shaft at the end of the fixed arm, a cylindrical cam hole therein to mount a cylindrical cam, and a slot on one side of the fixed arm to allow a cam guide of a movable arm to reciprocate;
• the movable arm retracting and extending while longitudinally sliding outside the fixed arm and having the cam guide protruding inward and engaged with a guide groove or a guide protrusion of the cylindrical cam across the slot of the fixed arm;
• the cylindrical cam disposed in the fixed arm in an axial direction of the fixed arm, having the guide groove or the guide protrusion engaged with the cam guide of the movable arm, and having a spline hole where a spline shaft of a bevel gear is fitted;
• a pedal composed of a pedal shaft coupled to an exposed end of the movable arm and a pedal plate coupled to the pedal shaft, the pedal plate not rotating with the pedal shaft;
• and
• a pair of bevel gears, one of which is fitted on the pedal shaft of the pedal and the other has a spline shaft fitted in the spline hole of the cylindrical cam to be coupled with the cylindrical cam, and which has a tooth ratio of 1:1.