Cycloidal gearbox

Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four basic components: a high-speed input shaft, a single 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 compound reducers, the first an eye on the cycloidal cam lobes engages cam followers in the housing. Cylindrical cam followers become teeth on the inner gear, and the amount of cam supporters exceeds the amount of cam lobes. The next track of compound cam lobes engages with cam followers on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus increasing torque and reducing velocity.

Compound cycloidal gearboxes provide ratios ranging from only 10:1 to 300:1 without stacking levels, as in regular planetary gearboxes. The gearbox’s compound reduction and can 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 acceleration 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 movement in different ways.
Planetary gearboxes
Planetary gearboxes are made up of three basic 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 insight shaft, which is connected to the servomotor. The sun gear transmits electric motor rotation to the satellites which, in turn, rotate in the stationary ring equipment. The ring equipment is portion of the gearbox housing. Satellite gears rotate on rigid shafts linked to the planet carrier and cause the earth carrier to rotate and, thus, turn the output shaft. The gearbox provides result shaft higher torque and lower rpm.

Planetary gearboxes generally have single or two-gear stages for reduction ratios ranging from 3:1 to 100:1. A third stage could be added for actually higher ratios, but 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 number of teeth in the pinion (input) gear.
Comparing the two
When deciding between cycloidal and planetary gearboxes, engineers should first consider the precision needed in the application form. If backlash and positioning precision 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 this by optimizing the reflected load/gearbox inertia and acceleration for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide greatest torque density, weight, and precision. Actually, 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 levels is unnecessary, therefore the gearbox can be shorter and less costly.
Finally, consider size. Many manufacturers offer square-framed planetary gearboxes that mate precisely with servomotors. But planetary gearboxes develop in length from single to two and three-stage styles as needed equipment 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 for as long. The compound reduction cycloidal gear teach handles all ratios within the same bundle size, therefore higher-ratio cycloidal gear boxes become also 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 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 offer engineers with a balance of performance, life, 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 are appropriate in any industry that uses servos or stepper motors. And although both are epicyclical reducers, the variations between many planetary gearboxes stem more from equipment geometry and manufacturing processes rather than principles of operation. But cycloidal reducers are more diverse 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 additional.

Great things about planetary gearboxes
• High torque density
• Load distribution and posting between planet gears
• Smooth operation
• High efficiency
• Low input inertia
• Low backlash
• Low cost

Cycloidal gearbox Benefits of cycloidal gearboxes
• Zero or very-low backlash stays relatively constant during life of the application
• Rolling rather than 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 regulate inertia in highly dynamic situations. Servomotors can only just control up to 10 times their own inertia. But if response time is critical, the motor should control less than four situations its own inertia.

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

Torque magnification. Gearboxes offer mechanical advantage by not only decreasing swiftness 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 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 instead of the more traditional involute tooth profile, which eliminates shear forces at any stage of contact. This style introduces compression forces, rather than those shear forces that would exist with an involute equipment mesh. That provides numerous functionality benefits such as high shock load capability (>500% of rating), minimal friction and use, lower mechanical service factors, among numerous others. The cycloidal style also has a large output shaft bearing period, which provides exceptional overhung load capabilities without requiring any additional expensive components.

Cycloidal advantages over additional 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 compact dimensional footprint
Exceptional “built-in” overhung load carrying capability
High efficiency (>95%) per reduction stage
Minimal reflected inertia to 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 suit for applications in heavy industry such as for example oil & gas, major and secondary steel processing, industrial food production, metal slicing and forming machinery, wastewater treatment, extrusion products, among others.

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