Cycloidal gearboxes or reducers consist of four basic components: a high-speed input shaft, a single 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 compound reducers, the first tabs on the cycloidal cam lobes engages cam fans in the housing. Cylindrical cam followers act as teeth on the internal gear, and the amount of cam followers exceeds the amount of cam lobes. The next track of compound cam lobes engages with cam supporters on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the result shaft, thus increasing torque and reducing acceleration.
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 will be calculated using:
where nhsg = the number of followers or rollers in the fixed housing and nops = the quantity for followers or rollers in the slower acceleration output shaft (flange).
There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations are based on gear geometry, heat treatment, and finishing procedures, cycloidal variations share fundamental design concepts but generate cycloidal motion in different ways.
Planetary gearboxes are made up of three fundamental force-transmitting elements: a sun gear, three or even more satellite or planet gears, and an interior ring gear. In an average gearbox, the sun equipment attaches to the insight shaft, which is connected to the servomotor. Sunlight gear transmits engine rotation to the satellites which, subsequently, rotate within the stationary ring gear. The ring gear is section of the gearbox casing. Satellite gears rotate on rigid shafts connected to the planet carrier and cause the earth carrier to rotate and, thus, turn the result shaft. The gearbox gives the result shaft higher torque and lower rpm.
Planetary gearboxes generally have single or two-gear stages for reduction ratios which range from 3:1 to 100:1. A third stage can 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 between cycloidal and planetary gearboxes, engineers should 1st consider the precision needed in the application. If backlash and positioning accuracy are necessary, then cycloidal gearboxes provide 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 rate for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide best 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 can be used. Nevertheless, if the mandatory ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking levels is unnecessary, therefore the gearbox can be shorter and less expensive.
Finally, consider size. Many manufacturers provide square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes grow in length from solitary 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 to higher than 100:1, respectively.
Conversely, cycloidal reducers are larger 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, therefore higher-ratio cycloidal equipment boxes become actually shorter than planetary variations with the same ratios.
Backlash, ratio, and size provide engineers with an initial gearbox selection. But selecting the most appropriate gearbox also entails bearing capacity, torsional stiffness, shock loads, environmental conditions, duty routine, 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 stability of performance, existence, and value, sizing and selection should be determined from the strain side back to the motor instead of the motor out.
Both cycloidal and planetary reducers work in virtually any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the distinctions between the majority of planetary gearboxes stem more from equipment geometry and manufacturing processes rather than principles of procedure. But cycloidal reducers are more diverse and share little in common with one another. There are advantages in each and engineers should consider the strengths and weaknesses when choosing 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
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, pancake design
• Ratios exceeding 200:1 in a concise size
• Quiet operation
The need for gearboxes
There are three basic reasons to employ a gearbox:
Inertia matching. The most common reason for selecting a gearbox is to control inertia in highly dynamic circumstances. Cycloidal gearbox Servomotors can only just control up to 10 times their own inertia. But if response time is critical, the engine should control significantly less than four instances its own inertia.
Speed reduction, Servomotors run more efficiently at higher speeds. Gearboxes help to keep motors operating at their ideal 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 primary 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 rather than the more traditional involute tooth profile, which eliminates shear forces at any stage of contact. This style introduces compression forces, rather than those shear forces that could exist with an involute equipment mesh. That provides numerous performance benefits such as high shock load capability (>500% of rating), minimal friction and wear, lower mechanical service elements, among many others. The cycloidal design also has a sizable output shaft bearing period, which gives exceptional overhung load capabilities without requiring any extra 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 electric motor for longer service life
Just ridiculously rugged because 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 commercial marketplace, and it is a perfect fit for applications in weighty industry such as for example oil & gas, main and secondary metal processing, industrial food production, metal slicing and forming machinery, wastewater treatment, extrusion devices, among others.