The total amount of free movement or play between mating mechanical components before they engage and transmit force. It is often intentionally designed into gears or valve trains to allow for thermal expansion and lubrication. Excessive clearance from wear creates harsh impacts, noise, and poor precision when reversing direction.
Check the valve lash on cylinder three, it sounds like a sewing machine.
Zero lash sounds ideal for precision, but in high-speed or high-heat applications, it guarantees the parts will bind and destroy themselves.
Also heard as
- backlash
- play
- slop
Related terms
Antibacklash
Designed to eliminate the clearance or play between mating mechanical parts like gears or lead screws.
Side play
The allowable lateral movement or clearance between assembled mechanical parts.
Deadband
A range of input movement or signal that produces no output response in a mechanical or control system.