Standard Backlash and Precision Backlash in Gear Reducers

Standard backlash refers to the allowable clearance between the output and input shafts of a gear reducer within normal design and manufacturing tolerances,which is an important indicator of gear reducer performance. Different types and specifications of gear reducers have different standard backlash values.

Taking common precision planetary reducer reducers as an example, in some industry standards, for small-sized planetary gear reducers (e.g., reduction ratios between 3-10), the standard backlash is typically controlled at 30-60 arcminutes. When the reduction ratio increases to 10-50, the standard backlash range may expand to 60-120 arcmin.

The standard backlash of cylindrical gear reducers also has corresponding regulations. Generally, for cylindrical gear reducers with a small module (e.g., a module between 1 and 3), the standard backlash is around 0.1-0.3 mm; when the module increases to 36, the standard backlash increases to 0.3-0.6 mm.

The standard backlash exists primarily to compensate for manufacturing and assembly errors, and to account for factors such as thermal expansion during gearbox operation.In this way, it ensures the normal operation of the transmission and prevents problems such as jamming or excessive wear between parts due to insufficient clearance.Precision backlash, on the other hand, is a more stringent backlash specification set for applications requiring extremely high precision. The value of precision backlash is typically much smaller than the standard backlash.

Taking planetary gearboxes as an example, in precision applications, for small-sized planetary gearboxes with reduction ratios between 3 and 10, the precision backlash can be controlled at 5-15 arc minutes; for reduction ratios between 10 and 50, the precision backlash can reach 15-30 arc minutes. In precision-grade cylindrical gear gearboxes, for a module of 13, the precision backlash can be controlled at 0.02-0.05 mm; for a module of 36, the precision backlash is only 0.05-0.1 mm. To achieve precise backlash control, more advanced processes and higher precision components are needed in the design, manufacturing, and assembly of gearboxes.For example, high-precision gear machining equipment is used to ensure the accuracy of gear tooth profile and helix angle; more precise adjustment methods are employed during assembly to strictly control the clearance between components. Precision backlash reducers are often used in equipment with extremely high motion accuracy requirements, such as semiconductor manufacturing equipment, optical inspection instruments, and some precision transmission mechanisms in the aerospace field, to ensure that the equipment can achieve precise motion control and positioning.