Cycloidal gearboxes or reducers contain four simple components: a high-speed input shaft, an individual 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 compound reducers, the first an eye on the cycloidal cam lobes engages cam fans in the casing. Cylindrical cam followers act as teeth on the inner gear, and the number of cam fans exceeds the number of cam lobes. The next track of compound cam lobes engages with cam supporters on the result shaft and transforms the cam’s eccentric rotation into concentric rotation of the result shaft, thus raising torque and reducing swiftness.
Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking phases, as in regular 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 simple design concepts but generate cycloidal motion in different ways.
Planetary gearboxes are made of three fundamental force-transmitting elements: a sun gear, three or even more satellite or planet gears, and an internal ring gear. In an average gearbox, the sun equipment attaches to the input shaft, which is connected to the servomotor. Sunlight gear transmits engine rotation to the satellites which, subsequently, rotate within the stationary ring equipment. The ring gear is part of the gearbox casing. Satellite gears rotate on rigid shafts linked to the planet carrier and trigger the earth carrier to rotate and, thus, turn the output shaft. The gearbox provides result shaft higher torque and lower rpm.
Planetary gearboxes generally have solitary or two-equipment Cycloidal gearbox stages for reduction ratios ranging from 3:1 to 100:1. A third stage can be added for also higher ratios, but 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 amount of teeth in the pinion (input) gear.
Comparing the two
When deciding between cycloidal and planetary gearboxes, engineers should 1st consider the precision needed in the application form. If backlash and positioning precision are necessary, then cycloidal gearboxes offer the most suitable choice. Removing backlash may also help the servomotor handle high-cycle, high-frequency moves.
Following, consider the ratio. Engineers can do this by optimizing the reflected load/gearbox inertia and speed for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes offer the best torque density, weight, and precision. Actually, few 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 hold advantages because stacking levels 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 precisely with servomotors. But planetary gearboxes develop in length from one 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 for as long. The compound reduction cycloidal gear teach handles all ratios within the same deal size, therefore higher-ratio cycloidal equipment boxes become even 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 consists of bearing capability, torsional stiffness, shock loads, environmental conditions, duty cycle, 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, lifestyle, and worth, sizing and selection ought to be determined from the load 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 although both are epicyclical reducers, the distinctions between the majority of planetary gearboxes stem more from equipment geometry and manufacturing processes instead of principles of procedure. 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 choosing one over the additional.
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 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 necessity 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 powerful situations. Servomotors can only just control up to 10 times their personal inertia. But if response time 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 to keep motors working 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 utilize 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 set of inner pins, keeping the decrease high and the rotational inertia low. The wheel incorporates 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, 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 ranking), minimal friction and put on, lower mechanical service factors, among numerous others. The cycloidal design also has a sizable output shaft bearing period, which provides exceptional overhung load features without requiring any additional 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 concise 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 since 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 reliable reducer in the industrial marketplace, in fact it is a perfect match for applications in weighty industry such as oil & gas, principal and secondary metal processing, commercial food production, metal cutting and forming machinery, wastewater treatment, extrusion tools, among others.