Cycloidal gearboxes
Cycloidal gearboxes or reducers contain four basic components: a high-speed input shaft, an individual or compound cycloidal cam, cam followers or rollers, and a slow-speed Cycloidal gearbox output shaft. The insight shaft attaches to an eccentric drive member that induces eccentric rotation of the cycloidal cam. In substance 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 number of cam fans exceeds the number of cam lobes. The second track of substance cam lobes engages with cam fans on the result shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus increasing torque and reducing rate.
Compound cycloidal gearboxes offer ratios ranging from only 10:1 to 300:1 without stacking stages, as in standard planetary gearboxes. The gearbox’s compound decrease and may 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 gradual quickness output shaft (flange).
There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations are based on gear geometry, heat treatment, and finishing processes, cycloidal variations share basic design principles 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 even more satellite or planet gears, and an internal ring gear. In a typical gearbox, the sun gear attaches to the input shaft, which is connected to the servomotor. Sunlight gear transmits motor rotation to the satellites which, subsequently, rotate in the stationary ring gear. The ring gear is area of the gearbox housing. Satellite gears rotate on rigid shafts connected to the planet carrier and trigger the planet carrier to rotate and, thus, turn the output shaft. The gearbox gives the 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, 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 inner 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. 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.
Next, consider the ratio. Engineers can do this by optimizing the reflected load/gearbox inertia and rate 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 provide ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers may be used. Nevertheless, if the mandatory ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking stages is unnecessary, so the gearbox can be shorter and less costly.
Finally, consider size. The majority of manufacturers provide square-framed planetary gearboxes that mate exactly with servomotors. But planetary gearboxes develop 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 then to greater than 100:1, respectively.
Conversely, cycloidal reducers are larger in diameter for the same torque yet are not for 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 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 grown to be somewhat of accessories to servomotors. For gearboxes to execute properly and provide engineers with a balance of performance, existence, and value, sizing and selection should be determined from the strain side back to the motor instead of the motor out.
Both cycloidal and planetary reducers are appropriate in any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the variations between the majority of planetary gearboxes stem more from gear geometry and manufacturing procedures instead of principles of operation. But cycloidal reducers are more varied and share little in common with each other. 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 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 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 need for gearboxes
There are three basic reasons to employ a gearbox:
Inertia matching. The most common reason for selecting a gearbox is to control inertia in highly dynamic circumstances. Servomotors can only just control up to 10 times their very own inertia. But if response period is critical, the electric motor should control significantly less than four instances its own inertia.
Speed reduction, Servomotors operate more efficiently at higher speeds. Gearboxes help keep motors operating at their optimum speeds.
Torque magnification. Gearboxes offer mechanical advantage by not merely 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 inner 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 point of contact. This style introduces compression forces, rather than those shear forces that could exist with an involute equipment mesh. That provides numerous overall performance benefits such as for example high shock load capability (>500% of ranking), minimal friction and put on, lower mechanical service elements, among many others. The cycloidal style also has a sizable output shaft bearing period, which provides exceptional overhung load capabilities without requiring any extra expensive components.
Cycloidal advantages over various 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 engine for longer service life
Just ridiculously rugged since all get-out
The overall EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP is the most dependable reducer in the commercial marketplace, in fact it is a perfect fit for applications in heavy industry such as for example oil & gas, main and secondary steel processing, commercial food production, metal trimming and forming machinery, wastewater treatment, extrusion apparatus, among others.