What are the similarities and differences between worm gear slew drive and spur gear slew drive?

Worm gear slew drive and spur gear slew drive are both highly integrated modular slewing reducers. Users do not need to purchase individual parts one by one and then assemble them into products with worm gear slew drive and spur gear slew drive functions. Reduce unnecessary production preparation procedures, greatly improve production efficiency. In a sense, the spur gear slew drive can replace all geared slewing bearings. Compared with slewing bearings, it has the advantages of simple installation, easy maintenance and greater saving installation space.


worm gear slew drive and spur gear slew drive


What are the similarities and differences in the design and use of the worm gear slew drive and the spur gear slew drive? Unique transmission will answer for you. 


Similarities


Worm gear worm shaft slew drive and spur gear slew drive both use slewing rings as the main moving parts. The slewing bearings play the role of driving the equipment to rotate and bearing the equipment load. The worm or gear is used as the driving part of the power input, housing, flange, general purpose support bearings, seals, etc. as accessories, can finally achieve 360° rotation through reasonable design and assembly, they can withstand large loads and are components with deceleration function. Both types of slewing drives have the characteristics of slewing, deceleration, bearing load, compact structure, fully sealed, dustproof and waterproof, modular design, convenient installation and maintenance.


Differences


1.The worm gear worm shaft slew drive uses a worm shaft to drive the slewing ring to rotate, the geared slew drive uses gear rotation to drive the slewing ring to rotate.


2.The worm gear worm shaft slew drive has a large gear ratio, the spur gear slew drive has a small gear ratio.


In the case of the same module and the same outer diameter, the gear ratio of the worm gear worm shaft slew drive is equal to the  teeth number of the slewing ring; The gear ratio of the spur gear slew drive is equal to the teeth number of the slewing ring/the teeth number of the gear. The teeth number of the gear is generally designed to 15 teeth, the gear ratio is 15 times different.


3.The worm gear slew drive has the characteristics of reverse self-locking, and the spur gear slew drive cannot be reversed self-locking.


The worm gear worm shaft slew drive can only be driven by the worm shaft to rotate the worm wheel, the worm wheel cannot be driven by the worm shaft to rotate. The reverse self-locking makes the slewing drive widely used in lifting equipment, aerial work platforms and other equipment. Under such working conditions, using worm gear worm shaft slewing drive does not require a braking device. In the absence of power, the equipment can still remain stationary for a long time. 

The gear of the spur gear slewing drive can drive the gear ring to rotate, the gear ring can also drive the gear to rotate in reverse, but cannot achieve reverse self-locking. This feature is also used in some special fields, such as wood grabbers, snow sweepers, etc. These devices cannot avoid collisions during use and do not self-lock in the event of a collision, which acts as a buffer to protect the equipment.


4.Worm gear slew drive limited speed is low, spur gear slew drive limited speed is high. 


The worm gear slew drive is driven by worm gear and worm shaft, worm gear and worm shaft slide on each other, high-speed rotation is easy to generate heat, causing the worm shaft to overheat and lock or directly damage. Generally, the worm gear slew drive speed does not exceed 2.5 rpm.

The spur gear slew drive works by the meshing of teeth and teeth, it's not easy to generate heat, the speed can usually reach 40-60 rpm.


5.Worm gear slew drive transmission efficiency is low, spur gear slew drive transmission efficiency is high. 


The friction force between the worm gear and the worm shaft of the worm gear slewing drive is large, transmission energy loss is large, so the transmission efficiency is low, usually only 30%-40%.

The friction resistance between the gears of the spur gear slewing drive is small and the loss is small, so the transmission efficiency is high, generally reaching 90%-95%, which is very efficient and saving energy. 


6.Worm gear slew drive has low rotation accuracy, spur gear slew drive has high rotation accuracy. 


The rotation accuracy of the ordinary worm gear slew drive is affected by various factors, it is impossible to achieve a small backlash. The accuracy of the precision type worm gear slewing drive can reach within 0.05°.

The spur gear slew drive has high rotation accuracy, gears and gear rings can be processed by grinding teeth, which can achieve higher accuracy. The spur gear slewing drive with a diameter of 1 meter can achieve an accuracy of less than 0.01°.



View more knowledge about slew drives: https://en.u-transmission.com

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