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 compound reducers, the first tabs on the cycloidal cam lobes engages cam followers in the housing. Cylindrical cam followers act as teeth on the internal gear, and the number of cam followers exceeds the number of cam lobes. The next track of compound cam lobes engages with cam followers on the result shaft and transforms the cam’s eccentric rotation into concentric rotation of the result shaft, thus increasing torque and reducing acceleration.
Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking levels, as in standard planetary gearboxes. The gearbox’s compound decrease and will 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 speed output shaft (flange).
There are several commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations are based on gear geometry, heat therapy, and finishing processes, cycloidal variations share fundamental design concepts but generate cycloidal movement in different ways.
Planetary gearboxes are made of three simple force-transmitting elements: a sun gear, three or more satellite or world gears, and an interior ring gear. In an average gearbox, the sun gear attaches to the insight shaft, which is linked to the servomotor. Sunlight gear transmits motor rotation to the satellites which, subsequently, rotate in the stationary ring equipment. The ring equipment is section of the cycloidal gearbox gearbox housing. 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 result shaft higher torque and lower rpm.
Planetary gearboxes generally have single or two-gear stages for reduction ratios ranging from 3:1 to 100:1. A third stage can be added for actually 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 tooth in the pinion (insight) gear.
Benefits of cycloidal gearboxes
• Zero or very-low backlash stays relatively constant during existence 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 is the far superior choice when compared to traditional planetary and cam indexing products.