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 input shaft attaches to an eccentric drive member that induces eccentric rotation of the cycloidal cam. In substance reducers, the first an eye on the cycloidal cam lobes engages cam followers in the casing. Cylindrical cam followers become teeth on the inner gear, and the amount of cam supporters exceeds the amount of cam lobes. The second 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 result shaft, thus raising torque and reducing velocity.
Compound cycloidal gearboxes provide ratios ranging from only 10:1 to 300:1 without stacking stages, 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 number for followers or rollers in the gradual 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 procedures, cycloidal variations share fundamental design concepts but generate cycloidal motion in different ways.
Planetary gearboxes are made of three simple 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 equipment attaches to the input 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 section of the gearbox casing. Satellite gears rotate on rigid shafts linked to the planet carrier and cause the earth carrier to rotate and, thus, turn the output shaft. The gearbox gives the result shaft higher torque and lower rpm.
Planetary gearboxes generally have solitary or two-gear stages for reduction ratios which range from 3:1 to 100:1. A third stage could be added for also higher ratios, but it is not common.
The ratio of a planetary gearbox is calculated using the next 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. If backlash and positioning precision are necessary, then cycloidal gearboxes provide best choice. Removing backlash may also help the servomotor manage high-cycle, high-frequency moves.
Next, consider the ratio. Engineers can do this by optimizing the reflected load/gearbox inertia and quickness for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes offer the best 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 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 specifically with servomotors. But planetary gearboxes grow in length from single to two and three-stage designs as needed equipment ratios go from significantly less than 10:1 to between 11:1 and 100:1, and then 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 deal size, so higher-ratio cycloidal gear boxes become actually shorter than planetary variations with the same ratios.
Backlash, ratio, and size provide engineers with an initial gearbox selection. But choosing the right 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 perform properly and offer engineers with a stability of performance, lifestyle, and value, sizing and selection should be determined from the load side back 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 although both are epicyclical reducers, the variations between most planetary gearboxes stem more from equipment geometry and manufacturing processes rather than principles of operation. But cycloidal reducers are more diverse and share small in common with each other. There are advantages in each and engineers should think about the strengths and weaknesses when selecting one over the additional.
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
Benefits of cycloidal gearboxes
• Zero or very-low backlash stays relatively constant during existence of the application
• Rolling rather than 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 selecting a gearbox is to regulate inertia in highly dynamic situations. Cycloidal gearbox servomotors can only just control up to 10 times their own inertia. But if response period is critical, the motor should control significantly less than four occasions its own inertia.
Speed reduction, Servomotors run more efficiently at higher speeds. Gearboxes help to keep motors operating at their optimum speeds.
Torque magnification. Gearboxes provide mechanical advantage by not merely decreasing quickness 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 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 stage 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 efficiency benefits such as for example high shock load capability (>500% of ranking), minimal friction and put on, lower mechanical service factors, among many others. The cycloidal style also has a large output shaft bearing span, which provides exceptional overhung load features without requiring any extra expensive components.
Cycloidal advantages over additional 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 electric motor for longer service life
Just ridiculously rugged because all get-out
The overall EP design proves to be extremely durable, and it needs minimal maintenance following installation. The EP is the most reliable reducer in the commercial marketplace, in fact it is a perfect match for applications in weighty industry such as oil & gas, primary and secondary metal processing, industrial food production, metal cutting and forming machinery, wastewater treatment, extrusion tools, among others.