Cycloidal gearbox

Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four simple 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 compound reducers, the first tabs on the cycloidal cam lobes engages cam supporters in the housing. Cylindrical cam followers act as teeth on the internal gear, and the amount of cam supporters 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 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 regular planetary gearboxes. The gearbox’s compound reduction and will be calculated using:

where nhsg = the number of followers or rollers in the fixed housing and nops = the number for followers or rollers in the slow 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 simple design concepts but generate cycloidal motion in different ways.
Planetary gearboxes
Planetary gearboxes are made up 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. The sun gear transmits electric motor rotation to the satellites which, in turn, rotate within the stationary ring equipment. The ring equipment is part of the gearbox casing. Satellite gears rotate on rigid shafts linked to the planet carrier and trigger the earth carrier to rotate and, thus, turn the output shaft. The gearbox provides output shaft higher torque and lower rpm.

Planetary gearboxes generally have one or two-equipment stages for reduction ratios ranging from 3:1 to 100:1. A third stage could be added for even higher ratios, but it is not common.

The ratio of a planetary gearbox is calculated using the following formula:where nring = the number of teeth in the inner 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. If backlash and positioning precision are crucial, then cycloidal gearboxes offer the most suitable choice. Removing backlash can also help the servomotor manage high-cycle, high-frequency moves.

Next, 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 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 hold advantages because stacking phases is unnecessary, therefore the gearbox could be shorter and less expensive.
Finally, consider size. Most manufacturers provide square-framed planetary gearboxes that mate precisely 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 to greater than 100:1, respectively.

Conversely, cycloidal reducers are bigger in diameter for the same torque yet are not as long. The compound reduction cycloidal gear teach handles all ratios within the same bundle 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 choosing the right gearbox also involves bearing capability, 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 balance of performance, lifestyle, and value, sizing and selection ought to be determined from the load 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 many planetary gearboxes stem more from equipment geometry and manufacturing procedures rather than principles of operation. But cycloidal reducers are more varied and share small in common with one another. There are advantages in each and engineers should think about the strengths and weaknesses when Cycloidal gearbox selecting one over the other.

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

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 concise 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 very own inertia. But if response time is critical, the engine should control significantly less than four instances its own inertia.

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

Torque magnification. Gearboxes offer mechanical advantage by not merely decreasing rate but also increasing result 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 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 gets rid of shear forces at any point of contact. This design introduces compression forces, rather than those shear forces that would can be found with an involute gear mesh. That provides numerous functionality benefits such as for example high shock load capability (>500% of rating), minimal friction and use, lower mechanical service elements, among many others. The cycloidal style also has a large output shaft bearing span, which provides exceptional overhung load capabilities without requiring any extra 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 electric motor 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 reliable reducer in the industrial marketplace, in fact it is a perfect fit for applications in large industry such as for example oil & gas, principal and secondary metal processing, commercial food production, metal slicing and forming machinery, wastewater treatment, extrusion products, among others.

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