The everyday shop word for backlash, especially when setting up axles, gearboxes and machine tool drives. Mechanics measure it with a dial indicator on a tooth while rocking the gear against a held pinion, and adjust it with shims, adjusters or center distance. Lash is quoted in thousandths of an inch or hundredths of a millimeter, such as eight thou on a ring gear.
Lash is at eight thou, right in the window, now paint it and see if the pattern agrees.
Rock the gear, don't spin it, and hold the pinion dead still, or the dial is reading bearing play instead of lash.
Also heard as
- backlash
- gear lash
- play
Related terms
Backlash
The play between mating teeth: how far one gear can rock before its teeth contact the other gear's teeth.
Slop
Shop word for too much play in a gear train or drive, felt as free movement before anything turns.
Set the pattern
Shop phrase for adjusting pinion depth and backlash on a bevel or hypoid set until the contact pattern is right.
Clunk
A single heavy knock when a drive takes up its backlash on a load reversal, such as on and off the throttle.