Cycloidal gearboxes or reducers contain four fundamental 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 track of the cycloidal cam lobes engages cam followers in the casing. Cylindrical cam followers become teeth on the inner gear, and the number of cam supporters exceeds the amount of cam lobes. The next track of compound cam lobes engages with cam fans on the result shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus raising torque and reducing acceleration.
Compound cycloidal gearboxes offer ratios ranging from as low as 10:1 to 300:1 without stacking phases, as in standard planetary gearboxes. The gearbox’s compound reduction and can 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 sluggish speed output shaft (flange).
There are several commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations are based on gear geometry, heat treatment, and finishing processes, cycloidal variations share simple design principles but generate cycloidal movement in different ways.
Planetary gearboxes are made of three fundamental force-transmitting elements: a sun gear, three or more satellite or world gears, and an interior ring gear. In a typical gearbox, the sun equipment attaches to the insight shaft, which is connected to the servomotor. The sun gear transmits motor rotation to the satellites which, subsequently, rotate within the stationary ring equipment. The ring gear is section of the gearbox housing. Satellite gears rotate on rigid shafts connected to the planet carrier and cause the earth 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-equipment stages for reduction ratios ranging from 3:1 to 100:1. A third stage can 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 number of teeth in the internal 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. If backlash and positioning accuracy are crucial, then cycloidal gearboxes provide best choice. Removing backlash may also help the servomotor deal with 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 provide greatest torque density, weight, and precision. Actually, few cycloidal reducers offer ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers may be used. However, if the mandatory ratio goes beyond 100:1, cycloidal gearboxes hold advantages because stacking phases is unnecessary, so the gearbox could be shorter and less costly.
Finally, consider size. Many manufacturers provide square-framed planetary gearboxes that mate precisely with servomotors. But planetary gearboxes grow in length from single to two and three-stage styles as needed equipment ratios go from significantly 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 handles all ratios within the same package deal size, so higher-ratio cycloidal equipment boxes become even shorter than planetary versions with the same ratios.
Backlash, ratio, and size provide engineers with an initial gearbox selection. But deciding on the best gearbox also requires bearing capacity, torsional stiffness, shock loads, environmental conditions, duty routine, and life.
From a mechanical perspective, gearboxes have become somewhat of Cycloidal gearbox accessories to servomotors. For gearboxes to execute properly and offer engineers with a stability of performance, life, and worth, sizing and selection should be determined from the strain side back 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 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 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 life of the application
• Rolling instead of 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 common reason for choosing the gearbox is to regulate inertia in highly powerful situations. Servomotors can only control up to 10 times their very own inertia. But if response time is critical, the electric motor should control significantly less than four occasions its own inertia.
Speed reduction, Servomotors operate more efficiently in higher speeds. Gearboxes help keep motors working at their optimum speeds.
Torque magnification. Gearboxes provide mechanical advantage by not only decreasing quickness but also increasing output torque.
The EP 3000 and our related products that use 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 set 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 eliminates 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 gear mesh. That provides several overall performance benefits such as high shock load capacity (>500% of rating), minimal friction and put on, lower mechanical service elements, among numerous others. The cycloidal design also has a big output shaft bearing span, 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 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 since all get-out
The entire EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP is the most dependable reducer in the industrial marketplace, and it is a perfect suit for applications in heavy industry such as oil & gas, main and secondary metal processing, commercial food production, metal trimming and forming machinery, wastewater treatment, extrusion equipment, among others.