Cycloidal gearboxes or reducers consist of four basic components: a high-speed input shaft, a single or compound 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 tabs 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 fans exceeds the amount 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 increasing torque and reducing acceleration.
Compound cycloidal gearboxes provide ratios ranging from only 10:1 to 300:1 without stacking phases, as in standard planetary gearboxes. The gearbox’s compound reduction and may 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 slow speed output shaft (flange).
There are several commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations derive from gear geometry, heat treatment, and finishing processes, cycloidal variations share basic design principles but generate cycloidal motion in different ways.
Planetary gearboxes are made up of three simple force-transmitting elements: a sun gear, three or more satellite or world 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 engine rotation to the satellites which, subsequently, rotate inside the stationary ring gear. The ring gear is portion of the gearbox housing. Satellite gears rotate on rigid shafts linked to the earth carrier and cause the planet carrier to rotate and, thus, turn the output shaft. The gearbox gives the output shaft higher torque and lower rpm.
Planetary gearboxes generally have one or two-gear 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 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, engineers should initial consider the precision needed in the application. If backlash and positioning precision are necessary, then cycloidal gearboxes provide most suitable choice. Removing backlash can 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 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 offer ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers may be used. Nevertheless, if the mandatory ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking stages is unnecessary, so the gearbox could be shorter and less expensive.
Finally, consider size. The majority of manufacturers offer square-framed planetary gearboxes that mate exactly with servomotors. But planetary gearboxes develop in length from one 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 as long. The compound decrease cycloidal gear teach Cycloidal gearbox handles all ratios within the same deal size, therefore higher-ratio cycloidal equipment boxes become also 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 routine, and life.
From a mechanical perspective, gearboxes have become somewhat of accessories to servomotors. For gearboxes to execute properly and provide engineers with a stability of performance, life, and worth, sizing and selection ought to be determined from the strain side back again to the motor instead of the motor out.
Both cycloidal and planetary reducers are appropriate in virtually any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the differences between most planetary gearboxes stem more from gear geometry and manufacturing procedures instead of principles of operation. But cycloidal reducers are more diverse and share little in common with one another. There are advantages in each and engineers should think about the strengths and weaknesses when selecting one over the other.
Great things about planetary gearboxes
• High torque density
• Load distribution and posting between planet gears
• Smooth operation
• High efficiency
• Low input inertia
• Low backlash
• Low cost
Benefits of cycloidal gearboxes
• Zero or very-low backlash stays relatively constant during life of the application
• Rolling rather than sliding contact
• Low wear
• Shock-load capacity
• Torsional stiffness
• Flat, pancake design
• Ratios exceeding 200:1 in a concise size
• Quiet operation
The necessity 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 situations. Servomotors can only just control up to 10 times their personal inertia. But if response period is critical, the electric motor should control significantly less than four moments its own inertia.
Speed reduction, Servomotors run more efficiently in higher speeds. Gearboxes help keep motors operating at their optimum speeds.
Torque magnification. Gearboxes offer mechanical advantage by not only 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 main power train is made up of an eccentric roller bearing that drives a wheel around a couple of inner 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 point of contact. This design introduces compression forces, instead of those shear forces that could can be found with an involute gear mesh. That provides several functionality benefits such as for example high shock load capacity (>500% of ranking), minimal friction and put on, lower mechanical service factors, among many others. The cycloidal design also has a big output shaft bearing period, which gives exceptional overhung load features 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 motor for longer service life
Just ridiculously rugged because all get-out
The overall EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP may be the most reliable reducer in the commercial marketplace, and it is a perfect fit for applications in heavy industry such as oil & gas, primary and secondary metal processing, commercial food production, metal reducing and forming machinery, wastewater treatment, extrusion products, among others.