Backlash of gear transmission and its elimination method

1.Backlash and the factors that produce backlash

The so-called backlash is a phenomenon in which the driven wheel lags when the driving wheel rotates in the reverse direction.The lagging corner is the backlash error angle.The main reason for backlash is due to the backlash of a pair of gears.In theory, a pair of meshing gears can be backlash-free.In some cases, however, backlash is necessary for the transmission to function properly.Due to the existence of backlash, the jamming of the gear teeth due to the machining error of the part can be avoided; in addition, it also provides a space for storing lubricating oil, as well as taking into account factors such as changes in the size of the parts due to temperature changes.However, the backlash error caused by the backlash in the reverse transmission will directly affect the transmission accuracy.

The main factors that produce backlash are: as far as the gear itself is concerned, there are larger center distances, tooth thickness deviations, base circle eccentricity and tooth profile errors.In addition, the eccentricity when the gear is mounted on the shaft, the radial deflection of the rolling bearing rotating race and the fit clearance between the fixed race and the housing will also affect the backlash.

In the reduction chain, the backlash error of the last stage (or the last few stages) gear has the greatest influence on the backlash error of the entire transmission chain.Therefore, it is of great significance to improve the manufacturing accuracy of the last stage (or last few stages) gears to reduce the backlash error of the entire transmission chain.At the same time, it is more reasonable to arrange the transmission ratios of all levels in order of first small and then large.

2.Methods to eliminate or reduce backlash

① Utilize spring force

② Fixed double gear

③ Using the contact hairspring

④ Adjust the center distance method