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June 18, 2020

Cycloidal gearboxes
Cycloidal gearboxes or reducers contain four basic 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 supporters in the casing. Cylindrical cam followers act as teeth on the inner gear, and the number of cam followers exceeds the number of cam lobes. The second track of substance cam lobes engages with cam followers 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 as low as 10:1 to 300:1 without stacking levels, as in standard planetary gearboxes. The gearbox’s compound decrease and can 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 slower velocity 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 procedures, cycloidal variations share basic design principles but generate cycloidal motion in different ways.
Planetary gearboxes
Planetary gearboxes are made up of three fundamental force-transmitting elements: a sun gear, three or even more satellite or planet 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, in turn, rotate in the stationary ring gear. The ring equipment is area of the gearbox housing. Satellite gears rotate on rigid shafts connected to the earth carrier and cause the planet carrier to rotate and, thus, turn the result shaft. The gearbox provides output shaft higher torque and lower rpm.

Planetary gearboxes generally have solitary or two-equipment stages for reduction ratios which range from 3:1 to 100:1. A third stage could be added for also higher ratios, nonetheless 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 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 accuracy are crucial, then cycloidal gearboxes provide best choice. Removing backlash may also help the servomotor manage high-cycle, high-frequency moves.

Following, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and swiftness for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide best 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 may be used. However, if the required ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking levels is unnecessary, therefore the gearbox could be shorter and less expensive.
Finally, consider size. Most manufacturers provide square-framed planetary gearboxes that mate exactly with servomotors. But planetary gearboxes grow in length from solitary to two and three-stage designs as needed equipment ratios go from 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 as long. The compound decrease cycloidal gear train handles all ratios within the same package deal size, so higher-ratio cycloidal equipment boxes become actually shorter than planetary versions with the same ratios.

Backlash, ratio, and size provide engineers with an initial gearbox selection. But deciding on the best gearbox also entails 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 execute properly and offer engineers with a stability of performance, existence, and value, sizing and selection should be determined from the strain side back again 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 Cycloidal gearbox majority of planetary gearboxes stem more from equipment geometry and manufacturing procedures instead of principles of operation. 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 remains 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 regulate inertia in highly powerful situations. Servomotors can only control up to 10 times their own inertia. But if response period is critical, the electric motor should control significantly less than four moments its own inertia.

Speed reduction, Servomotors operate more efficiently in higher speeds. Gearboxes help keep motors working at their optimal speeds.

Torque magnification. Gearboxes offer mechanical advantage by not only decreasing swiftness but also increasing result torque.

The EP 3000 and our related products that make use of 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 couple of internal 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 removes shear forces at any stage of contact. This style introduces compression forces, instead of those shear forces that would can be found with an involute equipment mesh. That provides numerous overall performance benefits such as for example high shock load capacity (>500% of ranking), minimal friction and use, lower mechanical service factors, among numerous others. The cycloidal style also has a huge output shaft bearing span, which gives exceptional overhung load features without requiring any extra expensive components.

Cycloidal advantages over other styles of gearing;

Capable of handling larger “shock” loads (>500%) of rating compared 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 because all get-out
The overall 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 large industry such as for example oil & gas, primary and secondary metal processing, commercial food production, metal trimming and forming machinery, wastewater treatment, extrusion tools, among others.