What is backlash then and how's it fixed :?:
Gear BacklashProperly functioning mechanical systems need to have a certain “clearanceâ€
(“gapâ€, “playâ€) between the components transmitting motion under load.
Clearance is necessary to avoid interference, wear, and excessive heat
generation, ensure proper lubrication, compensate for manufacturing tolerances
etc. Clearance in the gear mesh means that the gap between the teeth of one
gear is by a small amount larger than the tooth width of the mating gear.
We also find a certain clearance in the rolling bearings, namely a small clearance
between the inner race, rolling body (ball, roller) and outer race of the bearing.
The key and keyway of a shaft or hub usually have also clearance.
Wearing of the gears will increase backlash, the backlash can be reduce by moving the meshing gears closer together, however this is only possible if each gear is on a separate shaft due to different wear on different gears.
In a vehicle gearbox the drive gears all share the same shaft and the driven gears all share another shaft constantly meshing therfore is is not possible to reduse backlash within a gearbox.
Even if it were possible to reduce backlash it can not be eliminated completely as the backlash is necessary to prevent seizure of the gears.