Cycloidal gearboxes or reducers consist of four fundamental components: a high-speed input shaft, an individual or substance 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 compound reducers, the first track of the cycloidal cam lobes engages cam followers in the housing. Cylindrical cam followers become teeth on the inner gear, and the number of cam fans exceeds the amount of cam lobes. The next 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 can 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 sluggish speed output shaft (flange).
There are several commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations derive from gear geometry, heat therapy, and finishing processes, cycloidal variations share fundamental design concepts but generate cycloidal motion in different ways.
Planetary gearboxes are made of three basic force-transmitting elements: a sun gear, three or even more satellite or planet gears, and an interior ring gear. In a typical gearbox, the sun gear attaches to the input shaft, which is linked to the servomotor. The sun gear transmits engine rotation to the satellites which, in turn, rotate within the stationary ring equipment. The ring equipment is portion of the gearbox housing. Satellite gears rotate on rigid shafts connected to the earth carrier and trigger the earth carrier to rotate and, thus, turn the output shaft. The gearbox gives the result shaft higher torque and lower rpm.
Planetary gearboxes generally have one or two-gear stages for reduction ratios ranging from 3:1 to 100:1. A third stage could be added for even higher ratios, nonetheless 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 gear and nsun = the number of teeth in the pinion (input) gear.
Benefits of cycloidal gearboxes
• Zero or very-low backlash remains 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 in comparison with traditional planetary and cam indexing products.
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