Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four basic components: a high-speed input shaft, a single 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 fans in the housing. Cylindrical cam followers act as teeth on the inner gear, and the number of cam supporters exceeds the amount of cam lobes. The second track of compound cam lobes engages with cam supporters on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus raising torque and reducing quickness.
Compound cycloidal gearboxes offer ratios ranging from only 10:1 to 300:1 without stacking stages, as in regular planetary gearboxes. The gearbox’s compound decrease 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 slow rate output shaft (flange).
There are several commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations are based on gear geometry, heat therapy, and finishing processes, cycloidal variations share fundamental design principles but generate cycloidal movement in different ways.
Planetary gearboxes
Planetary gearboxes are made of three basic force-transmitting elements: a sun gear, three or even more satellite or world gears, and an interior ring gear. In an average gearbox, the sun equipment attaches to the input shaft, which is linked to the servomotor. The sun gear transmits electric motor rotation to the satellites which, subsequently, rotate within the stationary ring gear. The ring equipment is portion of the gearbox casing. Satellite gears rotate on rigid shafts linked to the planet carrier and cause 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-equipment stages for reduction ratios ranging from 3:1 to 100:1. A third stage can 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 inner ring gear and nsun = the amount of teeth in the pinion (input) gear.
Comparing the two
When deciding among cycloidal and planetary gearboxes, Cycloidal gearbox engineers should 1st consider the precision needed in the application. If backlash and positioning accuracy are crucial, then cycloidal gearboxes provide most suitable choice. Removing backlash may also help the servomotor handle high-cycle, high-frequency moves.
Following, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and quickness 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 required ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking stages is unnecessary, therefore the gearbox can be shorter and less costly.
Finally, consider size. Most manufacturers provide square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes develop in length from single to two and three-stage styles 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 but are not for as long. The compound decrease cycloidal gear train handles all ratios within the same package size, so higher-ratio cycloidal equipment boxes become actually 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 consists of 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, lifestyle, and worth, 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 work in virtually any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the distinctions between many planetary gearboxes stem more from equipment geometry and manufacturing processes instead of principles of operation. But cycloidal reducers are more diverse and share small in common with one another. There are advantages in each and engineers should consider the strengths and weaknesses when choosing 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 remains 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 common reason for selecting a gearbox is to control inertia in highly powerful circumstances. Servomotors can only control up to 10 times their very own inertia. But if response period is critical, the electric motor 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 ideal speeds.
Torque magnification. Gearboxes offer mechanical advantage by not merely 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 primary power train is comprised of an eccentric roller bearing that drives a wheel around a couple of internal 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 eliminates shear forces at any stage of contact. This style introduces compression forces, instead of those shear forces that would exist with an involute gear mesh. That provides a number of functionality benefits such as for example high shock load capability (>500% of rating), minimal friction and wear, lower mechanical service elements, among many others. The cycloidal design also has a large output shaft bearing span, which provides 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 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 as all get-out
The overall EP design proves to be extremely 
durable, and it needs 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 weighty industry such as for example oil & gas, primary and secondary metal processing, industrial food production, metal reducing and forming machinery, wastewater treatment, extrusion apparatus, among others.