Cycloidal gearboxes or reducers consist of four basic components: a high-speed input shaft, a single or compound cycloidal cam, cam followers or rollers, and a slow-speed output shaft. The input shaft attaches to an eccentric drive member that induces eccentric rotation of the cycloidal cam. In substance reducers, the first tabs on the cycloidal cam lobes engages cam supporters in the housing. Cylindrical cam followers become teeth on the inner gear, and the amount of cam supporters exceeds the amount of cam lobes. The second track of compound cam lobes engages with cam followers on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus raising torque and reducing quickness.
Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking stages, as in standard planetary gearboxes. The gearbox’s compound decrease and may be calculated using:
where nhsg = the number of followers or rollers in the fixed housing and nops = the number for followers or rollers in the slow velocity output shaft (flange).
There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations derive from gear geometry, heat therapy, and finishing processes, cycloidal variations share basic design principles but generate cycloidal motion in different ways.
Planetary gearboxes are made up of three simple force-transmitting elements: a sun gear, three or even more satellite or world gears, and an internal ring gear. In an average gearbox, the sun equipment attaches to the insight shaft, which is connected to the servomotor. The sun gear transmits electric motor rotation to the satellites which, in turn, rotate in the stationary ring equipment. The ring gear is part of the gearbox casing. Satellite gears rotate on rigid shafts connected to the planet carrier and trigger the planet carrier to rotate and, thus, turn the output shaft. The gearbox gives the output shaft higher torque and lower rpm.
Planetary gearboxes generally have one or two-equipment stages for reduction ratios ranging from 3:1 to 100:1. A third stage could be added for also higher ratios, but it is not common.
The ratio of a planetary gearbox is calculated using the next formula:
where nring = the number of teeth in the inner ring equipment and nsun = the number of teeth in the pinion (input) gear.
Great things about cycloidal gearboxes
• Zero or very-low backlash stays relatively constant during life of the application
• Rolling rather than sliding contact
• Low wear
• Shock-load capacity
• Torsional stiffness
• Flat, pancake design
• Ratios exceeding 200:1 in a compact size
• Quiet operation
Ever-Power Cycloidal Gear technology may be the far superior choice when compared to traditional planetary and cam indexing gadgets.
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