Cycloidal gearboxes or reducers contain four simple components: a high-speed input shaft, a single or compound cycloidal cam, cam followers or rollers, and a slow-speed output shaft. The insight shaft attaches to an eccentric drive member that induces eccentric rotation of the cycloidal cam. In compound reducers, the first an eye on the cycloidal cam lobes engages cam fans in the housing. Cylindrical cam followers become teeth on the inner gear, and the number of cam supporters exceeds the number of cam lobes. The second track of compound cam lobes engages with cam supporters on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the result shaft, thus raising torque and reducing speed.
Compound cycloidal gearboxes offer ratios ranging from only 10:1 to 300:1 without stacking stages, as in standard planetary gearboxes. The gearbox’s compound reduction and may be calculated using:
where nhsg = the amount of followers or rollers in the fixed housing and nops = the number for followers or rollers in the gradual speed output shaft (flange).
There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations are based on gear geometry, heat treatment, and finishing processes, cycloidal variations share basic design principles but generate cycloidal motion in different ways.
Planetary gearboxes are made up of three fundamental force-transmitting elements: a sun gear, three or even more satellite or planet gears, and an internal ring gear. In a typical gearbox, the sun equipment attaches to the input shaft, which is linked to the servomotor. The sun gear transmits engine rotation to the satellites which, in turn, rotate inside the stationary ring equipment. The ring equipment is area of the gearbox housing. Satellite gears rotate on rigid shafts connected to the planet carrier and cause the planet carrier to rotate and, thus, turn the result shaft. The gearbox gives the output shaft higher torque and lower rpm.
Planetary gearboxes generally have solitary or two-gear stages for reduction ratios which range from 3:1 to 100:1. A third stage can be added for even higher ratios, but it is not common.
The ratio of a planetary gearbox is calculated using the following formula:
where nring = the number of teeth in the internal ring equipment and nsun = the amount of teeth in the pinion (input) gear.
Benefits of cycloidal gearboxes
• Zero or very-low backlash stays relatively constant during life of the application
• Rolling instead of sliding contact
• Low wear
• Shock-load capacity
• Torsional stiffness
• Flat, pancake design
• Ratios exceeding 200:1 in a concise size
• Quiet operation
Ever-Power Cycloidal Equipment technology is the far superior choice when compared to traditional planetary and cam indexing devices.
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