Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four fundamental 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 compound reducers, the first tabs on the cycloidal cam lobes engages cam supporters in the housing. Cylindrical cam followers become teeth on the inner gear, and the amount of cam followers exceeds the number 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 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 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 quantity for followers or rollers in the slower acceleration 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 simple design principles but generate cycloidal motion in different ways.
Planetary gearboxes
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 a typical gearbox, the sun gear attaches to the insight 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 section of the gearbox casing. 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 provides output shaft higher torque and lower rpm.
Planetary gearboxes generally have solitary or two-gear stages for reduction ratios ranging from 3:1 to 100:1. A third stage could be added for actually higher ratios, nonetheless it is not common.
The ratio of a planetary gearbox is calculated using the following formula:where nring = the amount 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 first consider the precision needed in the Cycloidal gearbox application form. If backlash and positioning precision are crucial, then cycloidal gearboxes offer the most suitable choice. Removing backlash can 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 can be used. However, if the mandatory ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking levels is unnecessary, therefore the gearbox could be shorter and less expensive.
Finally, consider size. The majority of manufacturers provide square-framed planetary gearboxes that mate precisely with servomotors. But planetary gearboxes grow in length from solitary to two and three-stage styles as needed equipment 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 bigger in diameter for the same torque but are not as 
long. The compound decrease cycloidal gear teach handles all ratios within the same package size, therefore higher-ratio cycloidal equipment boxes become even shorter than planetary variations with the same ratios.
Backlash, ratio, and size provide engineers with an initial gearbox selection. But selecting the most appropriate gearbox also entails bearing capacity, 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 balance of performance, lifestyle, and value, sizing and selection ought to be determined from the load side back again to the motor instead of 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 differences between many planetary gearboxes stem more from gear geometry and manufacturing processes rather than principles of operation. But cycloidal reducers are more different 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 various other.
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 concise size
• Quiet operation
The need for gearboxes
There are three basic reasons to employ a gearbox:
Inertia matching. The most typical reason for choosing the gearbox is to regulate inertia in highly powerful circumstances. Servomotors can only just control up to 10 times their very own inertia. But if response time is critical, the electric motor should control significantly less than four times its own inertia.
Speed reduction, Servomotors operate more efficiently in higher speeds. Gearboxes help to keep motors operating at their optimum speeds.
Torque magnification. Gearboxes provide mechanical advantage by not only decreasing speed but also increasing result torque.
The EP 3000 and our related products that utilize 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 set of internal pins, keeping the decrease high and the rotational inertia low. The wheel includes a curved tooth profile rather than 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 high shock load capability (>500% of ranking), minimal friction and use, lower mechanical service factors, among many others. The cycloidal style also has a large output shaft bearing span, which gives 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 electric motor for longer service life
Just ridiculously rugged as 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 dependable reducer in the industrial marketplace, in fact it is a perfect suit for applications in large industry such as oil & gas, primary and secondary steel processing, industrial food production, metal trimming and forming machinery, wastewater treatment, extrusion equipment, among others.