23 March 2017

Spur gear backlash

In this article, we have discussed the backlash of the spur gear. so let us know first 
What is the backlash ?

  • Backlash is defined as the amount by which the width of tooth space exceeds the thickness of the engaging tooth measured along the pitch circle.

Backlash is the play a vital role in spur gear designing it plays between the missing teeth and it occurs only when teeth are in mesh.

Why provide backlash?

  • Backlash compensates for machining errors 
  • Backlash compensates for thermal expansion of teeth.
  • Backlash prevent the mating teeth from jamming together.
Methods to provide backlash :
  • The centre distance between mating gears is slightly increased.
  • The teeth of the gear are cut slightly thinner.
The magnitude of backlash is depended upon the diametral pitch or module and the centre distance.

The magnitude of backlash is very small for gear trains used in precision equipment and instruments.

The backlash and variation in centre distance have no effect on tooth action or velocity ratio.