|
July 2009
“PLAY”ing with Backlash
Understanding backlash and how it is measured
What is Backlash?
Backlash is defined as the play resulting from loose connections between
gears or other mechanical elements.
Unit of Measure
Backlash is measured in arc-minutes.
1 arc-minute = 1/60th of 1 degree or .0167 degree.
Measuring Backlash
Backlash in a gearbox is measured by locking the input shaft against rotation and applying a measured force to the output shaft. By using a load cell and potentiometer, a plot can be created. Backlash occurs at close to zero load when rotation is reversed.
Onvio Facts
In order to measure backlash accurately, it is important to capture all of the free play between the gears without measuring torsional wind-up. To insure accurate measurements, Onvio performed a variety of tests during development to arrive at the appropriate torque levels at which to measure backlash. We measured backdriven torque of the gearbox to determine the frictional forces that needed to be overcome to engage all gears resulting in rotation the input shaft relative to output rotation at the lowest possible load (typically 1-2% of rated load).
 |
