Cycloidal gearbox

Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four basic components: a high-speed input shaft, a single 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 substance reducers, the first track of the cycloidal cam lobes engages cam supporters in the casing. Cylindrical cam followers become teeth on the internal gear, and the amount of cam fans exceeds the number of cam lobes. The next track of substance cam lobes engages with cam fans on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus raising torque and reducing rate.

Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking phases, as in standard 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 sluggish rate output shaft (flange).

There are several 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 of three basic force-transmitting elements: a sun gear, three or more satellite or world gears, and an interior ring gear. In an average gearbox, the sun gear attaches to the input shaft, which is connected to the servomotor. Sunlight gear transmits motor rotation to the satellites which, in turn, rotate in the stationary ring gear. The ring gear is portion of the gearbox casing. Satellite gears rotate on rigid shafts linked to the earth carrier and trigger the earth carrier to rotate and, thus, turn the result shaft. The gearbox gives the 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 also higher ratios, nonetheless 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 number of teeth in the pinion (input) gear.
Comparing the two
When deciding among cycloidal and planetary gearboxes, engineers should 1st consider the precision needed in the application form. If backlash and positioning accuracy are Cycloidal gearbox necessary, then cycloidal gearboxes provide most suitable choice. Removing backlash can 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 velocity for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide best torque density, weight, and precision. In fact, few 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 mandatory ratio goes beyond 100:1, cycloidal gearboxes hold advantages because stacking phases is unnecessary, therefore the gearbox could be shorter and less costly.
Finally, consider size. Many manufacturers offer square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes grow in length from single to two and three-stage designs as needed gear ratios go from significantly 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 for as long. The compound decrease cycloidal gear train handles all ratios within the same package size, therefore 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 selecting the most appropriate 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 stability of performance, existence, and worth, sizing and selection ought to be determined from the strain side back 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 variations between most planetary gearboxes stem more from equipment geometry and manufacturing procedures rather than principles of procedure. But cycloidal reducers are more different and share little in common with each other. 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 sharing between planet gears
• Smooth operation
• High efficiency
• Low input inertia
• Low backlash
• Low cost

Benefits of 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 employ a gearbox:

Inertia matching. The most common reason for choosing the gearbox is to control inertia in highly powerful situations. Servomotors can only just control up to 10 times their personal inertia. But if response time is critical, the motor should control less than four occasions its own inertia.

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

Torque magnification. Gearboxes offer mechanical advantage by not only decreasing quickness 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 inner pins, keeping the decrease high and the rotational inertia low. The wheel incorporates a curved tooth profile instead of the more traditional involute tooth profile, which removes 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 several functionality benefits such as high shock load capacity (>500% of rating), minimal friction and use, lower mechanical service factors, among many others. The cycloidal style also has a huge output shaft bearing span, which gives exceptional overhung load capabilities without requiring any additional 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 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 entire EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP may be the most reliable reducer in the industrial marketplace, in fact it is a perfect match for applications in large industry such as oil & gas, main and secondary steel processing, industrial food production, metal cutting and forming machinery, wastewater treatment, extrusion products, among others.