Cycloidal gearboxes or reducers contain four basic 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 substance reducers, the first tabs on the cycloidal cam lobes engages cam followers in the casing. Cylindrical cam followers become teeth on the internal gear, and the amount of cam supporters exceeds the number of cam lobes. The next 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 result shaft, thus raising torque and reducing velocity.
Compound cycloidal gearboxes offer ratios ranging from as low as 10:1 to 300:1 without stacking stages, as in standard planetary gearboxes. The gearbox’s compound reduction and may be calculated using:
where nhsg = the amount of followers or rollers in the fixed housing and nops = the quantity for followers or rollers in the slower speed 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 procedures, cycloidal variations share fundamental design concepts but generate cycloidal movement in different ways.
Planetary gearboxes are made of three simple force-transmitting elements: a sun gear, three or even more satellite or world gears, and an interior ring gear. In a typical gearbox, the sun gear attaches to the insight shaft, which is linked to the servomotor. The sun gear transmits electric motor rotation to the satellites which, in turn, rotate in the stationary ring gear. The ring equipment is part of the gearbox casing. Satellite gears rotate on rigid shafts linked to the earth 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 single or two-gear stages for reduction ratios ranging from 3:1 to 100:1. A third stage could 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 between cycloidal and planetary gearboxes, engineers should first consider the precision needed in the application form. If backlash and positioning precision are crucial, then cycloidal gearboxes offer the best choice. Removing backlash may also help the servomotor deal with high-cycle, high-frequency moves.
Following, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and swiftness 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 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 phases is unnecessary, so the gearbox could be shorter and less expensive.
Finally, consider size. Most manufacturers provide square-framed planetary gearboxes that mate exactly with servomotors. But planetary gearboxes grow in length from one to two and three-stage styles as needed equipment ratios go from less than 10:1 to between 11:1 and 100:1, and to higher than 100:1, respectively.
Conversely, cycloidal reducers are bigger in diameter for the same torque yet are not as long. The compound reduction cycloidal gear train handles all ratios within the same package size, so higher-ratio cycloidal gear boxes become actually shorter than planetary variations 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 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 perform properly and provide engineers with a balance of performance, existence, and value, 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 are appropriate in virtually any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the variations between most planetary gearboxes stem more from gear geometry and manufacturing processes rather than principles of procedure. But cycloidal reducers are more different and share small in common with each other. There are advantages in each and engineers should consider the strengths and weaknesses when selecting one over the other.
Benefits of planetary gearboxes
• High torque density
• Load distribution and posting 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, Cycloidal gearbox pancake design
• Ratios exceeding 200:1 in a concise size
• Quiet operation
The necessity for gearboxes
There are three basic reasons to use a gearbox:
Inertia matching. The most common reason for choosing the gearbox is to control inertia in highly powerful circumstances. Servomotors can only control up to 10 times their own inertia. But if response period is critical, the engine 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 optimum speeds.
Torque magnification. Gearboxes offer mechanical advantage by not only decreasing acceleration 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 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 incorporates a curved tooth profile instead of 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 equipment mesh. That provides numerous functionality benefits such as for example high shock load capacity (>500% of ranking), minimal friction and put on, lower mechanical service elements, among many others. The cycloidal style also has a big output shaft bearing period, which provides exceptional overhung load features without requiring any extra expensive components.
Cycloidal advantages over various other styles of gearing;
Able to handle 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 engine 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 is the most dependable reducer in the commercial marketplace, and it is a perfect suit for applications in heavy industry such as oil & gas, main and secondary steel processing, commercial food production, metal cutting and forming machinery, wastewater treatment, extrusion apparatus, among others.