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Backlash analysis of spur gear slew drive

Publish time:2021/06/28 News Views:745

Spur gear slew drive (SP series) is a kind of slewing ring, gear, housing, adapter flange, support bearing, seal and other components, after reasonable design, component manufacturing, debugging, assembly and other processes, the output can bear axial force, radial force, tilting moment at the same time has a certain gear ratio, referred to as slewing drive.


The pinions of the spur gear slew drive and the tooth meshing of the slewing rings will have a certain gap, which is called backlash. According to different applications of slewing drives, customers have different requirements for backlash, such as:

a. For working conditions that often rotate in the same direction, there is no requirement for gear backlash, only smooth transmission and durability are required;

b. In high speed and large load transmission conditions, the backlash should not be too large, the gear transmission should be more stable, reducing noise and vibration;

c. The automation equipment that requires exact stop and indexing has strict requirements on backlash. Usually the rotation accuracy is within 1 arc minute, some require as smaller as possible, some working conditions require zero backlash.


Ordinary spur gear slew drive, the gear rings of slewing ring and pinion teeth are hardened after machining, then they can be used directly for assembly and debugging to ensure that the transmission is smooth.


Spur gear slew drive with high speed and large load transmission. The slewing ring gear rings are usually specially designed and the gears are ground. Such spur gear slewing drives have the characteristics of large output torque, stable operation, low noise and low vibration.


The spur gear slew drive with strict requirements for backlash, the slewing bearings adopt high precision design, gear rings’ teeth adopt grinding process, ground, transmission gears’ teeth also grind process, the housings, flanges, support bearings and other components are all adopt precision design to control all aspects that affect the backlash, to keep improving when assembling and debugging, it is necessary to check backlash at multiple points to meet customer requirements.


Backlash will affect the transmission accuracy, which is what users care about most. If the backlash is large, it will not be able to stop accurately, or the repeat positioning accuracy will not meet the requirements, the equipment will not be able to achieve normal functions and complete the scheduled actions.


For applications with particularly high backlash requirements, we recommend double gears or multiple gears to drive at the same time to eliminate backlash. The backlash mainly comes from the tooth runout of the slewing ring. We can only adjust the backlash of the tooth high point to zero, then the backlash of the tooth low point is the tooth runout. If the backlash at the low point of the tooth is adjusted to zero, the high point of the tooth is an interference fit, the rotation will have a jam phenomenon, which will affect the linearity of the output torque, transmission efficiency will decrease and the service life of the slewing drive will be shortened. Double gears or multiple gears are driven at the same time to eliminate backlash. The backlash of the slewing ring gear ring tooth high point corresponding to each gear can be adjusted to zero respectively, so that when in use, there are always gears meshing in the small backlash area near the slewing ring tooth height, which can continue to improve the processing accuracy In the case, reduce the tooth backlash.


There is another advantage of multiple gears transmission at the same time. The output torque of each gear is relatively small, the impact load of each gear is relatively small during exact stop. This design is suitable for high precision and large inertia applications.

Backlash analysis of spur gear slew drive
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Backlash analysis of spur gear slew drive
This article introduces the backlash analysis of the spur gear slew drive and the effect of backlash on the slewing drive.
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