Backlash in Precision Applications

Backlash, or lost motion on reversal, is a key accuracy parameter in planetary gear reducer selection. It affects positioning accuracy and repeatability and is generally specified in arcminutes (arcmin). A smaller value indicates less lost motion. Requirements vary considerably: general material handling and conveying can tolerate more backlash, while precision positioning, robot joints and measuring equipment require low-backlash designs.

Rated Torque and Acceleration Torque

Torque specifications distinguish rated torque from acceleration (peak) torque. Rated torque is the output torque that can be sustained under continuous operating conditions; acceleration torque is the short-duration torque capacity. Continuous-duty applications must be checked against the rated torque. Applications with frequent starts and stops or rapid acceleration also require verification of acceleration torque and the permitted load cycle; checking the peak value alone is insufficient.

Reference Technical Specifications

Parameter	Typical range	Description
Single-stage ratio	3:1–10:1	Multiple stages provide higher reduction ratios
Backlash (precision grade)	1–5 arcmin	P0 grade: 1–3 arcmin; P1 grade: 3–5 arcmin
Ingress protection rating	IP65	For demanding operating environments
Gear material	20CrMnTi	Carburised and hardened; tooth surface hardness 58–62 HRC

Selecting a Ratio and Output Speed

Single-stage planetary ratios typically range from 3:1 to 10:1. Multiple stages provide higher reduction ratios. Select the ratio from the motor’s rated speed and the required machine output speed. Because multi-stage arrangements are less efficient than single-stage designs, use as few stages as practicable while meeting the required reduction ratio.

Planetary Gear Reducer Selection Support

Send the required accuracy, load torque, speed and installation conditions to SANYOO’s technical team for selection assistance. Visit www.sanyoogear.com for further technical information.