Cycloidal gearboxes or reducers consist of four basic components: a high-speed input shaft, an individual 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 substance 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 followers exceeds the amount of cam lobes. The second track of compound cam lobes engages with cam fans on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the result shaft, thus increasing torque and reducing speed.
Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking phases, as in regular planetary gearboxes. The gearbox’s compound decrease and may be calculated using:
where nhsg = the amount of followers or rollers in the fixed housing and nops = the quantity for followers or rollers in the gradual quickness output shaft (flange).
There are several commercial Cycloidal gearbox variations of cycloidal reducers. And unlike planetary gearboxes where variations derive from gear geometry, heat treatment, and finishing procedures, cycloidal variations share fundamental design principles but generate cycloidal movement in different ways.
Planetary gearboxes are made of three basic force-transmitting elements: a sun gear, three or even more satellite or world gears, and an internal ring gear. In a typical gearbox, the sun equipment attaches to the input shaft, which is linked to the servomotor. Sunlight gear transmits motor rotation to the satellites which, in turn, rotate within the stationary ring gear. The ring gear is part of the gearbox housing. Satellite gears rotate on rigid shafts linked to the planet carrier and trigger the planet carrier to rotate and, thus, turn the result shaft. The gearbox gives the result shaft higher torque and lower rpm.
Planetary gearboxes generally have solitary or two-gear stages for reduction ratios ranging from 3:1 to 100:1. A third stage can be added for even higher ratios, nonetheless it is not common.
The ratio of a planetary gearbox is calculated using the next formula:where nring = the number of teeth in the internal ring gear and nsun = the number of teeth in the pinion (input) gear.
Comparing the two
When deciding among cycloidal and planetary gearboxes, engineers should initial consider the precision needed in the application form. If backlash and positioning accuracy are crucial, then cycloidal gearboxes offer the best choice. Removing backlash may also help the servomotor deal with high-cycle, high-frequency moves.
Following, consider the ratio. Engineers can do this by optimizing the reflected load/gearbox inertia and speed for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes offer the best torque density, weight, and precision. In fact, few cycloidal reducers offer ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers can be used. However, if the mandatory ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking stages is unnecessary, so the gearbox can be shorter and less costly.
Finally, consider size. The majority of manufacturers provide square-framed planetary gearboxes that mate exactly with servomotors. But planetary gearboxes develop in length from single to two and three-stage styles as needed gear ratios go from less than 10:1 to between 11:1 and 100:1, and to greater than 100:1, respectively.
Conversely, cycloidal reducers are larger in diameter for the same torque but are not as long. The compound decrease cycloidal gear teach handles all ratios within the same bundle size, therefore higher-ratio cycloidal equipment boxes become actually shorter than planetary variations with the same ratios.
Backlash, ratio, and size provide engineers with a preliminary gearbox selection. But selecting the most appropriate gearbox also involves bearing capacity, torsional stiffness, shock loads, environmental conditions, duty cycle, and life.
From a mechanical perspective, gearboxes have become somewhat of accessories to servomotors. For gearboxes to execute properly and provide engineers with a balance of performance, lifestyle, and value, sizing and selection ought to be determined from the strain side back again to the motor instead of the motor out.
Both cycloidal and planetary reducers are appropriate in any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the variations between many planetary gearboxes stem more from gear geometry and manufacturing procedures rather than principles of procedure. But cycloidal reducers are more varied and share small in common with one another. There are advantages in each and engineers should consider the strengths and weaknesses when choosing one over the additional.
Benefits of planetary gearboxes
• High torque density
• Load distribution and sharing between planet gears
• Smooth operation
• High efficiency
• Low input inertia
• Low backlash
• Low cost
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 compact size
• Quiet operation
The necessity for gearboxes
There are three basic reasons to use a gearbox:
Inertia matching. The most typical reason for selecting a gearbox is to control inertia in highly dynamic situations. Servomotors can only just control up to 10 times their own inertia. But if response period is critical, the engine should control less than four occasions its own inertia.
Speed reduction, Servomotors operate more efficiently at higher speeds. Gearboxes help keep motors working at their optimum speeds.
Torque magnification. Gearboxes provide mechanical advantage by not only decreasing velocity but also increasing result torque.
The EP 3000 and our related products that use cycloidal gearing technology deliver the most robust solution in the most compact footprint. The primary power train is comprised of an eccentric roller bearing that drives a wheel around a set of internal pins, keeping the reduction high and the rotational inertia low. The wheel incorporates a curved tooth profile instead of the more traditional involute tooth profile, which gets rid of shear forces at any point of contact. This design introduces compression forces, instead of those shear forces that could can be found with an involute gear mesh. That provides numerous functionality benefits such as high shock load capability (>500% of rating), minimal friction and wear, lower mechanical service elements, among numerous others. The cycloidal style also has a large output shaft bearing span, which provides exceptional overhung load features without requiring any additional expensive components.
Cycloidal advantages over additional styles of gearing;
Able to handle larger “shock” loads (>500%) of rating compared to worm, helical, etc.
High reduction ratios and torque density in a compact dimensional footprint
Exceptional “built-in” overhung load carrying capability
High efficiency (>95%) per reduction stage
Minimal reflected inertia to electric motor for longer service life
Just ridiculously rugged because all get-out
The entire EP design proves to be extremely durable, and it needs minimal maintenance following installation. The EP may be the most reliable reducer in the industrial marketplace, and it is a perfect match for applications in heavy industry such as oil & gas, main and secondary metal processing, commercial food production, metal slicing and forming machinery, wastewater treatment, extrusion tools, among others.