Cycloidal gearbox

Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four fundamental components: a high-speed input shaft, a single or compound 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 substance reducers, the first track of the cycloidal cam lobes engages cam fans in the casing. Cylindrical cam followers become teeth on the internal gear, and the number of cam fans exceeds the number 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 swiftness.

Compound cycloidal gearboxes provide ratios ranging from only 10:1 to 300:1 without stacking stages, as in standard planetary gearboxes. The gearbox’s compound reduction and will be calculated using:

where nhsg = the amount of followers or rollers in the fixed housing and nops = the number for followers or rollers in the slower speed 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 procedures, cycloidal variations share basic design principles but generate cycloidal motion in different ways.
Planetary gearboxes
Planetary gearboxes are made of three fundamental force-transmitting elements: a sun gear, three or even more satellite or world gears, and an interior ring gear. In a typical gearbox, the sun gear attaches to the input shaft, which is linked to the servomotor. The sun gear transmits motor rotation to the satellites which, subsequently, rotate within the stationary ring equipment. The ring gear is portion of the gearbox casing. Satellite gears rotate on rigid shafts connected to the earth carrier and trigger the earth carrier to rotate and, thus, turn the result shaft. The gearbox provides result shaft higher torque and lower rpm.

Planetary gearboxes generally have one or two-gear stages for reduction ratios which range 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 next formula:where nring = the number 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 1st consider the precision needed in the application. If backlash and positioning accuracy are necessary, then cycloidal gearboxes provide most suitable choice. Removing backlash may also help the servomotor deal with high-cycle, high-frequency moves.

Following, 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 best torque density, weight, and precision. In fact, not many cycloidal reducers provide 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 hold advantages because stacking phases is unnecessary, so the gearbox can be shorter and less expensive.
Finally, consider size. Many manufacturers offer square-framed planetary gearboxes that mate exactly with servomotors. But planetary gearboxes grow in length from single to two and three-stage styles as needed equipment ratios go from significantly less than 10:1 to between 11:1 and 100:1, and to higher than 100:1, respectively.

Conversely, cycloidal reducers are bigger in diameter for the same torque yet are not for as long. The compound reduction cycloidal gear teach handles all ratios within the same package deal size, therefore higher-ratio cycloidal equipment boxes become also shorter than planetary variations with the same ratios.

Backlash, ratio, and size provide engineers with a preliminary gearbox selection. But deciding on the best gearbox also entails bearing capacity, 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 stability of performance, life, and value, sizing and selection ought to 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 distinctions between the 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 one another. There are advantages in each and engineers should consider the strengths and weaknesses when selecting one over the additional.

Great things about planetary gearboxes
• High torque density
• Load Cycloidal gearbox 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 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 need for gearboxes
There are three basic reasons to use a gearbox:

Inertia matching. The most common reason for choosing the gearbox is to regulate inertia in highly dynamic situations. Servomotors can only control up to 10 times their personal inertia. But if response period 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 operating at their optimum speeds.

Torque magnification. Gearboxes offer mechanical advantage by not only decreasing acceleration 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 main power train is comprised of an eccentric roller bearing that drives a wheel around a set of internal 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 eliminates shear forces at any point of contact. This design introduces compression forces, rather than those shear forces that would exist with an involute gear mesh. That provides numerous performance benefits such as high shock load capability (>500% of ranking), minimal friction and wear, lower mechanical service factors, among numerous 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;

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 motor 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 commercial marketplace, and it is a perfect match for applications in weighty industry such as for example oil & gas, major and secondary steel processing, industrial food production, metal slicing and forming machinery, wastewater treatment, extrusion devices, among others.

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