Cycloidal gearboxes or reducers contain four simple 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 substance reducers, the first track of the cycloidal cam lobes engages cam fans in the housing. Cylindrical cam followers become teeth on the inner gear, and the amount of cam fans exceeds the number of cam lobes. The second track of compound cam lobes engages with cam supporters 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 only 10:1 to 300:1 without stacking stages, as in regular planetary gearboxes. The gearbox’s compound decrease and may be calculated using:
where nhsg = the number of followers or rollers in the fixed housing and nops = the quantity for followers or rollers in the slow velocity output shaft (flange).
There are many 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 principles but generate cycloidal movement in different ways.
Planetary gearboxes are made of three fundamental force-transmitting elements: a sun gear, three or more satellite or world gears, and an internal ring gear. In an average gearbox, the sun gear attaches to the input shaft, which is connected to the servomotor. The sun gear transmits engine rotation to the satellites which, subsequently, rotate inside the stationary ring gear. The ring gear is area of the Cycloidal gearbox gearbox casing. 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 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 amount of teeth in the internal ring gear and nsun = the amount 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. If backlash and positioning accuracy are necessary, then cycloidal gearboxes offer the most suitable choice. Removing backlash may also help the servomotor handle high-cycle, high-frequency moves.
Following, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and rate for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide greatest torque density, weight, and precision. In fact, not many cycloidal reducers offer ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers can be used. Nevertheless, if the mandatory ratio goes beyond 100:1, cycloidal gearboxes hold advantages because stacking stages is unnecessary, therefore the gearbox can be shorter and less expensive.
Finally, consider size. Most manufacturers provide square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes grow in length from one to two and three-stage designs as needed equipment 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 reduction cycloidal gear teach handles all ratios within the same deal size, so higher-ratio cycloidal gear 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 entails bearing capability, 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 offer engineers with a stability of performance, life, and value, sizing and selection should be determined from the load side back 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 although both are epicyclical reducers, the distinctions between many planetary gearboxes stem more from gear geometry and manufacturing processes rather than principles of procedure. But cycloidal reducers are more varied and share little in common with one another. There are advantages in each and engineers should think about the strengths and weaknesses when selecting one over the other.
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 existence 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 common reason for choosing the gearbox is to regulate inertia in highly dynamic circumstances. Servomotors can only control up to 10 times their very own inertia. But if response time is critical, the engine should control less than four times its own inertia.
Speed reduction, Servomotors run more efficiently at higher speeds. Gearboxes help keep motors working at their ideal speeds.
Torque magnification. Gearboxes offer mechanical advantage by not merely decreasing swiftness but also increasing result 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 reduction high and the rotational inertia low. The wheel includes a curved tooth profile rather than the more traditional involute tooth profile, which gets rid of shear forces at any point of contact. This style introduces compression forces, rather than those shear forces that would can be found with an involute equipment mesh. That provides numerous overall performance benefits such as high shock load capacity (>500% of rating), minimal friction and wear, lower mechanical service factors, among numerous others. The cycloidal design also has a large output shaft bearing span, which provides exceptional overhung load capabilities without requiring any additional expensive components.
Cycloidal advantages over various other styles of gearing;
Capable of handling 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 engine for longer service life
Just ridiculously rugged as all get-out
The entire EP design proves to be extremely durable, and it needs minimal maintenance following installation. The EP is the most reliable reducer in the commercial marketplace, and it is a perfect match for applications in heavy industry such as for example oil & gas, main and secondary metal processing, industrial food production, metal trimming and forming machinery, wastewater treatment, extrusion equipment, among others.