Cycloidal gearboxes or reducers contain four basic components: a high-speed input shaft, a single or substance 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 substance 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 supporters exceeds the number of cam lobes. The next 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 output shaft, thus increasing torque and reducing speed.
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 reduction and can 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 slow rate 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 simple design principles but generate cycloidal movement in different ways.
Planetary gearboxes are made up 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 equipment attaches to the input shaft, which is connected to the servomotor. The sun gear transmits engine rotation to the satellites which, in turn, rotate in the stationary ring gear. The ring equipment is portion of the gearbox casing. Satellite gears rotate on rigid shafts connected to the planet carrier and cause the earth carrier to rotate and, thus, turn the result shaft. The gearbox gives the output shaft higher torque and lower rpm.
Planetary gearboxes generally have single or two-equipment stages for reduction ratios which range from 3:1 to 100:1. A third stage can be added for also higher ratios, but it is not common.
The ratio of a planetary gearbox is calculated using the following formula:
where nring = the amount of teeth in the internal ring equipment and nsun = the amount 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 Equipment technology may be the far superior choice when compared to traditional planetary and cam indexing products.
Want to understand about cycloidal gearbox? Please check out the site.