Cycloidal gearboxes or reducers consist of four fundamental components: a high-speed input shaft, a single or substance 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 an eye on the cycloidal cam lobes engages cam supporters in the casing. Cylindrical cam followers become teeth on the inner gear, and the number of cam supporters exceeds the amount of cam lobes. The second track of substance cam lobes engages with cam supporters on the result shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus raising torque and reducing rate.
Compound cycloidal gearboxes offer ratios ranging from only 10:1 to 300:1 without stacking levels, as in standard planetary gearboxes. The gearbox’s compound decrease 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 gradual quickness output shaft (flange).
There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations derive from gear geometry, heat treatment, and finishing processes, cycloidal variations share fundamental design principles but generate cycloidal movement in different ways.
Planetary gearboxes are made up of three fundamental force-transmitting elements: a sun gear, three or even more satellite or planet gears, and an interior ring gear. In an average gearbox, the sun equipment attaches to the input shaft, which is connected to the servomotor. Sunlight gear transmits motor rotation to the satellites which, in turn, rotate Cycloidal gearbox within the stationary ring gear. The ring equipment is portion 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 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 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 following 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 initial consider the precision needed in the application form. If backlash and positioning precision are crucial, then cycloidal gearboxes provide best choice. Removing backlash can also help the servomotor handle high-cycle, high-frequency moves.
Next, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and speed for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide 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 can be used. However, if the required ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking stages is unnecessary, so the gearbox could be shorter and less costly.
Finally, consider size. Most manufacturers provide square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes grow in length from one to two and three-stage designs as needed equipment 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 but are not as long. The compound reduction cycloidal gear teach handles all ratios within the same package 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 choosing the right gearbox also requires bearing capability, torsional stiffness, shock loads, environmental conditions, duty routine, and life.
From a mechanical perspective, gearboxes have become somewhat of accessories to servomotors. For gearboxes to perform properly and offer engineers with a stability of performance, life, and worth, 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 virtually any industry that uses servos or stepper motors. And although both are epicyclical reducers, the variations between most planetary gearboxes stem more from gear geometry and manufacturing processes instead of principles of operation. But cycloidal reducers are more diverse 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 various other.
Benefits of planetary gearboxes
• High torque density
• Load distribution and sharing between planet gears
• Smooth operation
• High efficiency
• Low input inertia
• Low backlash
• Low cost
Great things about 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 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 period is critical, the engine should control less than four instances its own inertia.
Speed reduction, Servomotors run more efficiently at higher speeds. Gearboxes help to keep motors operating at their ideal speeds.
Torque magnification. Gearboxes provide 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 made up 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 gets rid of shear forces at any stage of contact. This design introduces compression forces, instead of those shear forces that could can be found with an involute equipment mesh. That provides several performance benefits such as high shock load capacity (>500% of ranking), minimal friction and use, lower mechanical service elements, among numerous others. The cycloidal style also has a big output shaft bearing span, which gives exceptional overhung load capabilities without requiring any additional expensive components.
Cycloidal advantages over additional styles of gearing;
Able to handle larger “shock” loads (>500%) of rating in comparison 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 electric motor for longer service life
Just ridiculously rugged as all get-out
The overall EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP is the most reliable reducer in the commercial marketplace, and it is a perfect match for applications in large industry such as oil & gas, principal and secondary metal processing, commercial food production, metal trimming and forming machinery, wastewater treatment, extrusion products, among others.