Harmonic Drive Gears basic construction
abstract:Harmonic drives are a type of gearing that uses controllable elastic deformation of the main flexibl...
Harmonic drives are a type of gearing that uses controllable elastic deformation of the main flexible wheel. This means that they do not use backlash to achieve high reduction ratios. They also use elliptical cams for motion control. Harmonic drives also offer high positional accuracy and rotational accuracy. These gears have been used in space applications, including lunar rovers and space station winches. They have also been used in robotics and medical x-ray machines.The basic construction of a harmonic drive gear consists of three parts: the elliptical cam (or wave generator), the flexspline and the circular spline. The wave generator is fixed to the drive shaft and imparts a continuous elliptical motion to the flexspline. The flexspline is a thin steel cup with teeth that engage with the circular spline. The circular spline is also made of gear teeth and has an internal gear teeth 43. The asymmetrical plug 50 is inserted into the ball bearing assembly 48 in a manner similar to the mounting of plug 24.Each complete clockwise rotation of the wave generator results in the flexspline moving counterclockwise by two teeth. This is due to the fact that half of the gear teeth mating at 180 degrees symmetrically with the other half.