Cycloidal gearboxes or reducers consist of four simple 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 compound reducers, the first track of the cycloidal cam lobes engages cam fans 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 result shaft, thus increasing torque and reducing speed.
Compound cycloidal gearboxes offer ratios ranging from as low as 10:1 to 300:1 without stacking stages, as in regular 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 slower quickness 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 concepts but generate cycloidal movement in different ways.
Planetary gearboxes are made of three basic force-transmitting elements: a sun gear, three or more satellite or planet gears, and an internal ring gear. In a typical gearbox, the sun equipment attaches to the insight shaft, which is connected to the servomotor. The sun gear transmits electric motor rotation to the satellites which, subsequently, rotate inside the stationary ring gear. The ring gear is Cycloidal gearbox portion of the gearbox housing. Satellite gears rotate on rigid shafts linked to the earth carrier and trigger 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 one 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 inner ring gear and nsun = the amount of teeth in the pinion (input) gear.
Comparing the two
When deciding between cycloidal and planetary gearboxes, engineers should initial consider the precision needed in the application. If backlash and positioning precision are crucial, then cycloidal gearboxes offer the best choice. Removing backlash can also help the servomotor deal with high-cycle, high-frequency moves.
Next, consider the ratio. Engineers can do this by optimizing the reflected load/gearbox inertia and swiftness for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes offer the greatest torque density, weight, and precision. Actually, 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 levels is unnecessary, so the gearbox could be shorter and less expensive.
Finally, consider size. Many manufacturers offer 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 then to greater than 100:1, respectively.
Conversely, cycloidal reducers are larger in diameter for the same torque but are not as long. The compound reduction cycloidal gear teach handles all ratios within the same bundle size, therefore higher-ratio cycloidal gear boxes become actually shorter than planetary versions with the same ratios.
Backlash, ratio, and size provide engineers with a preliminary gearbox selection. But selecting the most appropriate gearbox also entails bearing capability, torsional stiffness, shock loads, environmental conditions, duty routine, and life.
From a mechanical perspective, gearboxes have grown to be somewhat of accessories to servomotors. For gearboxes to perform properly and offer engineers with a balance of performance, life, and worth, sizing and selection ought to be determined from the load side back to the motor as opposed to the motor out.
Both cycloidal and planetary reducers work in any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the differences between the majority of planetary gearboxes stem more from gear geometry and manufacturing processes rather than principles of operation. But cycloidal reducers are more different and share little in common with each other. 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
Great things about cycloidal gearboxes
• Zero or very-low backlash stays relatively constant during lifestyle 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 employ a gearbox:
Inertia matching. The most typical reason for selecting a gearbox is to control inertia in highly dynamic circumstances. Servomotors can only control up to 10 times their personal inertia. But if response period is critical, the motor should control less than four situations its own inertia.
Speed reduction, Servomotors operate more efficiently in higher speeds. Gearboxes help to keep motors working at their optimum speeds.
Torque magnification. Gearboxes provide mechanical advantage by not only decreasing rate but also increasing output torque.
The EP 3000 and our related products that utilize cycloidal gearing technology deliver the most robust solution in the most compact footprint. The main power train is made up of an eccentric roller bearing that drives a wheel around a couple of inner pins, keeping the decrease high and the rotational inertia low. The wheel incorporates a curved tooth profile instead of the more traditional involute tooth profile, which removes shear forces at any stage of contact. This style introduces compression forces, rather than those shear forces that could can be found with an involute equipment mesh. That provides several performance benefits such as for example high shock load capability (>500% of ranking), minimal friction and wear, lower mechanical service elements, among many others. The cycloidal design also has a huge output shaft bearing span, which gives exceptional overhung load capabilities without requiring any extra expensive components.
Cycloidal advantages over other styles of gearing;
Able to handle larger “shock” loads (>500%) of rating in comparison to worm, helical, etc.
High reduction ratios and torque density in a concise 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 since all get-out
The overall EP design proves to be extremely durable, and it needs minimal maintenance following installation. The EP is the most dependable reducer in the industrial marketplace, and it is a perfect match for applications in large industry such as oil & gas, primary and secondary steel processing, commercial food production, metal slicing and forming machinery, wastewater treatment, extrusion equipment, among others.