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 track of the cycloidal cam lobes engages cam followers in the housing. Cylindrical cam followers become teeth on the inner gear, and the number of cam fans exceeds the number of cam lobes. The second track of substance cam lobes engages with cam supporters on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus raising torque and reducing quickness.
Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking levels, as in regular planetary gearboxes. The gearbox’s compound reduction and may be calculated using:
where nhsg = the amount of followers or Cycloidal gearbox rollers in the fixed housing and nops = the quantity for followers or rollers in the slow quickness 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 principles but generate cycloidal motion in different ways.
Planetary gearboxes are made of three basic force-transmitting elements: a sun gear, three or 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. Sunlight gear transmits motor rotation to the satellites which, in turn, rotate in the stationary ring gear. The ring equipment is section of the gearbox casing. Satellite gears rotate on rigid shafts connected to the planet carrier and cause the planet carrier to rotate and, thus, turn the result shaft. The gearbox gives the output 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 actually 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 first consider the precision needed in the application form. If backlash and positioning accuracy are necessary, 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 this by optimizing the reflected load/gearbox inertia and velocity for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes offer the best torque density, weight, and precision. In fact, not many cycloidal reducers offer ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers can be used. Nevertheless, if the required ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking stages is unnecessary, so the gearbox can be shorter and less expensive.
Finally, consider size. Many manufacturers offer square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes develop in length from solitary to two and three-stage designs as needed equipment 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 but are not as long. The compound reduction cycloidal gear teach handles all ratios within the same bundle size, therefore higher-ratio cycloidal gear 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 involves 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 offer engineers with a stability of performance, lifestyle, 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 any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the distinctions between most planetary gearboxes stem more from gear geometry and manufacturing processes instead of principles of operation. But cycloidal reducers are more varied and share small in common with each other. There are advantages in each and engineers should consider the strengths and weaknesses when choosing one over the additional.
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
Great things about cycloidal gearboxes
• Zero or very-low backlash remains relatively constant during existence 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 use a gearbox:
Inertia matching. The most common reason for choosing the gearbox is to regulate inertia in highly powerful circumstances. Servomotors can only just control up to 10 times their own inertia. But if response time is critical, the electric motor should control less than four instances its own inertia.
Speed reduction, Servomotors operate more efficiently at higher speeds. Gearboxes help to keep motors working at their optimal speeds.
Torque magnification. Gearboxes provide mechanical advantage by not merely decreasing rate but also increasing output 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 comprised of an eccentric roller bearing that drives a wheel around a couple of internal 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 gets rid of shear forces at any point of contact. This style introduces compression forces, rather than those shear forces that could can be found with an involute gear mesh. That provides several performance benefits such as high shock load capability (>500% of rating), minimal friction and put on, lower mechanical service elements, among many others. The cycloidal style also has a large output shaft bearing period, which provides exceptional overhung load capabilities without requiring any additional expensive components.
Cycloidal advantages over various 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 compact 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 needs minimal maintenance following installation. The EP may be the most dependable reducer in the industrial marketplace, in fact it is a perfect suit for applications in heavy industry such as for example oil & gas, major and secondary metal processing, commercial food production, metal reducing and forming machinery, wastewater treatment, extrusion devices, among others.