The cyclo-drive gearbox is a variation of a planetary gearbox. They have the added advantage of not using gear teeth to drive the shafts; rather they use an internal offset cam arrangement to drive rolling pins that turn a cycloidal wheel inside the gearbox. The rollers are capable of taking 500% overload without breaking the gearbox. One other benefit of the cyclo-drive gearbox for users is that many models are grease filled and do not use oil.
These gearboxes are much less likely to fail in unexpected overload situations. By using grease lubrication instead of oil lubrication there is less chance of lubricant loss through shaft seals. Reduced likelihood of lubricant loss is particularly important with vertically mounted gearboxes, as with tank agitators.
Method Of Operation
In the picture above the central gray colored shaft is the input shaft. The same shaft is shown yellow in the picture below. It is made with an eccentric cam at the end of the shaft. The cam sits inside the center of the cycloid disc. As it rotates the cam moves the cycloid disc in a circular orbit. The outer fixed pins and rollers restrain the disc and force it to roll around inside the ring of fixed pins. As the disc rolls it moves the inner set of pins and roller attached to the output shaft.
One rotation of the cam moves the cycloid disc over one outer pin. As the disc rotates the inner pins are forced around with it at the speed of the disc. This means that there is a reduction in gearing and the output turns at slower revolutions than the input shaft.
You can see a video clip on the TV image at the Sumitomo website products pages at their website www.smcyclo.com.
The nature of the design makes their size much smaller than a conventional toothed gear drive for the same gearing ratio. This means you need less space to mount them. They weigh less and are more easily manoeuvered by installation and repair personnel. The smaller internals and sliding action of the rotating components makes the gearbox quieter than conventional gearboxes.
They are ideal where shock loads are expected because all the parts are in compression and not in tension, as is the case with conventional gearbox teeth. Their quietness makes them ideal to use where operators need to work close to equipment or for equipment located near offices, hospitals and the like. Their reliability and longevity is outstanding!
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