Backlash (engineering) Calculator

This lash or play online tool is used to calculate the gear operating center backlash and gear tooth thickness backlash.


Formula for Gear Operating Center Backlash :

Backlash is known as lash or play, is a clearance or lost motion in a mechanism caused by gaps between the parts.

Backlash, measured on the pitch circle, due to operating center modifications is defined by: The speed of the machine. The material in the machine.

bc = 2 ΔC tan(θ)


bc - backlash due to operating center distance modifications

ΔC - actual and ideal operating center differences

θ - pressure angle in degrees

Formula for Gear Tooth Thickness Backlash :

This backlash due to tooth thickness modifications is used to find the motion loss due to increasing the center distance between the gears.

Backlash due to tooth thickness changes is typically measured along the pitch circle and is defined by:

bt = ti - ta


bt - backlash due to tooth thickness

ti - ideal tooth thickness in mm

ta - actual tooth thickness in mm