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June 18, 2020

Cycloidal gearboxes
Cycloidal gearboxes or reducers contain four fundamental components: a high-speed input shaft, an individual 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 supporters in the casing. Cylindrical cam followers become teeth on the inner gear, and the number of cam fans exceeds the amount of cam lobes. The second track of compound cam lobes engages with cam fans on the result shaft and transforms the cam’s eccentric rotation into concentric rotation of the result shaft, thus raising torque and reducing acceleration.

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 will 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 slower quickness output shaft (flange).

There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations derive from gear geometry, heat therapy, and finishing processes, cycloidal variations share fundamental design concepts but generate cycloidal motion in different ways.
Planetary gearboxes
Planetary gearboxes are made up of three simple 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 insight shaft, which is linked to the servomotor. Sunlight gear transmits motor rotation to the satellites which, subsequently, rotate inside the stationary ring equipment. The ring gear is part of the Cycloidal gearbox gearbox housing. Satellite gears rotate on rigid shafts connected to the earth 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 solitary or two-gear stages for reduction ratios ranging from 3:1 to 100:1. A third stage could be added for also 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 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 form. If backlash and positioning precision are necessary, then cycloidal gearboxes provide best choice. Removing backlash may also help the servomotor deal with high-cycle, high-frequency moves.

Next, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and quickness for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide best torque density, weight, and precision. Actually, not many cycloidal reducers provide ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers may be used. Nevertheless, if the required ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking levels is unnecessary, so the gearbox can be shorter and less costly.
Finally, consider size. Many manufacturers provide square-framed planetary gearboxes that mate exactly with servomotors. But planetary gearboxes grow in length from solitary to two and three-stage styles as needed gear ratios go from significantly less than 10:1 to between 11:1 and 100:1, and then to higher than 100:1, respectively.

Conversely, cycloidal reducers are bigger in diameter for the same torque but are not for as long. The compound decrease cycloidal gear teach handles all ratios within the same package size, so higher-ratio cycloidal gear boxes become even shorter than planetary versions with the same ratios.

Backlash, ratio, and size provide engineers with a preliminary gearbox selection. But deciding on the best gearbox also requires bearing capability, torsional stiffness, shock loads, environmental conditions, duty routine, and life.

From a mechanical perspective, gearboxes have become somewhat of accessories to servomotors. For gearboxes to perform properly and offer engineers with a balance of performance, lifestyle, and value, sizing and selection ought to be determined from the load side back to the motor instead of the motor out.

Both cycloidal and planetary reducers work in virtually any industry that uses servos or stepper motors. And although both are epicyclical reducers, the differences between most planetary gearboxes stem more from gear geometry and manufacturing processes instead of principles of procedure. But cycloidal reducers are more different and share small in common with each other. 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

Great things about 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 need for gearboxes
There are three basic reasons to use a gearbox:

Inertia matching. The most common reason for selecting a gearbox is to control inertia in highly powerful situations. Servomotors can only control up to 10 times their very own inertia. But if response period is critical, the motor should control significantly less than four situations its own inertia.

Speed reduction, Servomotors run more efficiently in 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 output torque.

The EP 3000 and our related products that use 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 set of inner pins, keeping the decrease high and the rotational inertia low. The wheel includes a curved tooth profile rather than the more traditional involute tooth profile, which removes shear forces at any point of contact. This style introduces compression forces, rather than those shear forces that could exist with an involute gear mesh. That provides numerous functionality benefits such as high shock load capability (>500% of ranking), minimal friction and use, lower mechanical service elements, among many others. The cycloidal design also has a big output shaft bearing span, which gives exceptional overhung load capabilities without requiring any additional expensive components.

Cycloidal advantages over other 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 engine for longer service life
Just ridiculously rugged because all get-out
The entire EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP may be the most dependable reducer in the commercial marketplace, in fact it is a perfect fit for applications in weighty industry such as for example oil & gas, main and secondary steel processing, commercial food production, metal reducing and forming machinery, wastewater treatment, extrusion gear, among others.