Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of four basic components: a high-speed input shaft, a single or substance cycloidal cam, cam Cycloidal gearbox 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 an eye on the cycloidal cam lobes engages cam supporters in the housing. Cylindrical cam followers become teeth on the inner gear, and the number of cam supporters exceeds the number of cam lobes. The next track of substance cam lobes engages with cam fans on the output 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 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 sluggish swiftness 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 concepts but generate cycloidal motion 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 internal ring gear. In a typical gearbox, the sun gear attaches to the input shaft, which is linked to the servomotor. The sun gear transmits motor rotation to the satellites which, in turn, rotate in the stationary ring gear. The ring gear is section of the gearbox housing. Satellite gears rotate on rigid shafts linked to the planet carrier and trigger the planet carrier to rotate and, thus, turn the result shaft. The gearbox provides output shaft higher torque and lower rpm.
Planetary gearboxes generally have solitary or two-equipment stages for reduction ratios ranging from 3:1 to 100:1. A third stage can be added for also 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 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 offer the best choice. Removing backlash can also help the servomotor deal with high-cycle, high-frequency moves.
Next, consider the ratio. Engineers can do that 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. In fact, few 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 hold advantages because stacking phases is unnecessary, so the gearbox could be shorter and less costly.
Finally, consider size. The majority of manufacturers offer square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes develop in length from solitary to two and three-stage styles as needed gear ratios go from less than 10:1 to between 11:1 and 100:1, and then to higher than 100:1, respectively.
Conversely, cycloidal reducers are bigger in diameter for the same torque yet are not for as long. The compound decrease cycloidal gear train handles all ratios within the same bundle size, therefore higher-ratio cycloidal gear boxes become actually shorter than planetary versions with the same ratios.
Backlash, ratio, and size provide engineers with an initial gearbox selection. But selecting the most appropriate gearbox also consists of bearing capability, 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 perform properly and provide engineers with a stability of performance, lifestyle, and value, sizing and selection ought to be determined from the strain side back to the motor instead of the motor out.
Both cycloidal and planetary reducers work in virtually any industry that uses servos or stepper motors. And although both are epicyclical reducers, the variations between many planetary gearboxes stem more from gear geometry and manufacturing processes instead of principles of operation. But cycloidal reducers are more different and share little 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.
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
Great things about cycloidal gearboxes
• Zero or very-low backlash stays relatively constant during lifestyle of the application
• Rolling instead of 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 use a gearbox:
Inertia matching. The most typical reason for choosing the gearbox is to control inertia in highly dynamic situations. Servomotors can only just control up to 10 times their personal inertia. But if response time is critical, the motor should control significantly less than four times its own inertia.
Speed reduction, Servomotors run more efficiently in higher speeds. Gearboxes help keep motors working at their optimum speeds.
Torque magnification. Gearboxes offer mechanical advantage by 
not merely decreasing quickness but also increasing result torque.
The EP 3000 and our related products that make use of 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 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 gets rid of shear forces at any point of contact. This style introduces compression forces, instead of those shear forces that would can be found with an involute equipment mesh. That provides a number of functionality benefits such as for example high shock load capacity (>500% of rating), minimal friction and use, lower mechanical service elements, among numerous 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;
Able to handle larger “shock” loads (>500%) of rating in comparison 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 since all get-out
The entire EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP is the most reliable reducer in the industrial marketplace, and it is a perfect match for applications in weighty industry such as for example oil & gas, principal and secondary steel processing, industrial food production, metal trimming and forming machinery, wastewater treatment, extrusion tools, among others.