Backlash – Coupling
What is backlash?
Backlash in unintended movement that occurs when rotating the shafts during an alignment. It is most often caused by looseness in the coupling. Backlash is most often caused by looseness in the coupling. On misaligned machines, backlash can cause measurements error. In order to eliminate measurement errors, backlash must be controlled.
Elimination of backlash:
There are two guidelines present for controlling backlash.
Direction of Rotation: When possible, rotate the shafts in the direction that the machine operates.
These techniques should be followed even when there is no obvious backlash. Not controlling backlash can result in non-repeatable readings.
Preload the coupling before zeroing the dials: Keep the moveable shaft coupling half in the lead relative to the stationary shaft coupling half. Achieve this by preloading; holding just one half of the coupling and letting gravity position the other half. Switch hands to maintain the preload as you roll over 12 o clock.