Backlash Gear

backlash error in motion occurs when gears change direction. exists because there gap between trailing face of driving tooth , leading face of tooth behind on driven gear, , gap must closed before force can transferred in new direction. term backlash can used refer size of gap, not phenomenon causes; thus, 1 speak of pair of gears having, example, 0.1 mm of backlash. pair of gears designed have 0 backlash, presuppose perfection in manufacturing, uniform thermal expansion characteristics throughout system, , no lubricant. therefore, gear pairs designed have backlash. provided reducing tooth thickness of each gear half desired gap distance. in case of large gear , small pinion, however, backlash taken entirely off gear , pinion given full sized teeth. backlash can provided moving gears further apart. backlash of gear train equals sum of backlash of each pair of gears, in long trains backlash can become problem.

for situations require precision, such instrumentation , control, backlash can minimised through 1 of several techniques. instance, gear can split along plane perpendicular axis, 1 half fixed shaft in usual manner, other half placed alongside it, free rotate shaft, springs between 2 halves providing relative torque between them, 1 achieves, in effect, single gear expanding teeth. method involves tapering teeth in axial direction , letting gear slide in axial direction take slack.