Strain wave gearboxes

Zero backlash - ideal for robotic / medical / optics applications

Our range of strain wave reducers offers a wide range of configurations and ratios to meet your expectations.

Composition of strain wave gearing

The composition of strain wave (also referred to as "harmonic") transmissions differs from planetary structures.

 

Harmonic gearboxes are mainly composed of three parts:

  • The wave generator, which is composed of a flexible bearing and an oval cam. The wave generator is usually installed at the input end of the speed reducer. The inner ring of the flexible bearing is fixed on the CAM, and the outer ring is elastic, and forms an oval

  • The flexible wheel (or flexwheel) is a thin elastomer part with outer teeth, and is usually installed at the output end of the reducer.
  • The rigid wheel is a rigid, circular part with inner teeth. It has a greater number of teeth than the flexible wheel and is usually fixed on the reducer body. 

This construction offers 2 main interests :

  • High ratios can be achieved in a single-stage construction (compact solution)

  • Backlash is reduced to just arc-seconds (planetary gearboxes can only reach a reduced backlash of 1 arc-minute until they become overconstrained)

Principle of harmonic reduction

The teeth of the two wheels constantly change their meshing status between 4 stages : biting, meshing, biting and disconnecting.

The harmonic gear reduction uses the elastic deformation of the flexible wheel. The fact of having a different number of teeth between the rigid wheel and the flexible wheel produces a differential reduction. 

  • The wave generator expends the flexible wheel and curves it into an oval shape.
  • The flexible wheel teeth and the rigid wheel teeth enter a complete mesh-like state, while the flexible wheel teeth and rigid wheel inner teeth at both ends of the short axis are separated. 
  • Teeth between the long axis and the short axis of the ellipse engage gradually.