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 compound reducers, the first tabs on the cycloidal cam lobes engages cam followers in the housing. Cylindrical cam followers become teeth on the inner gear, and the amount of cam followers exceeds the number of cam lobes. The second 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 result shaft, thus increasing torque and reducing swiftness.
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 reduction and can 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 gradual acceleration 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 processes, cycloidal variations share basic 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 world gears, and an internal ring gear. In an average gearbox, the sun equipment attaches to the input shaft, which is linked to the servomotor. The sun gear transmits electric motor rotation to the satellites which, in turn, rotate within the stationary ring gear. The ring gear is part of the gearbox casing. Satellite gears rotate on rigid shafts connected to the earth carrier and cause the earth carrier to rotate and, thus, turn the result shaft. The gearbox provides 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 could be added for also higher ratios, but it is not common.
The ratio of a planetary gearbox is calculated using the following formula:where nring = the amount of teeth in the inner 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 crucial, then cycloidal gearboxes offer the best choice. Removing backlash can 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 rate for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide best torque density, weight, and precision. In fact, few 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 hold Cycloidal gearbox advantages because stacking levels is unnecessary, therefore the gearbox can be shorter and less expensive.
Finally, consider size. Many manufacturers offer square-framed planetary gearboxes that mate precisely with servomotors. But planetary gearboxes develop in length from one to two and three-stage designs as needed gear 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 for as long. The compound reduction cycloidal gear teach handles all ratios within the same package size, so higher-ratio cycloidal equipment boxes become actually shorter than planetary versions with the same ratios.
Backlash, ratio, and size provide engineers with a preliminary 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 grown to be somewhat of accessories to servomotors. For gearboxes to perform properly and offer engineers with a balance of performance, existence, and worth, sizing and selection ought to be determined from the strain side back to the motor instead of 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 distinctions between many 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 one another. 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 sharing between planet gears
• Smooth operation
• High efficiency
• Low input inertia
• Low backlash
• Low cost
Great things about 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 concise size
• Quiet operation
The necessity 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 powerful circumstances. Servomotors can only just control up to 10 times their very own inertia. But if response period is critical, the electric motor should control less than four moments its own inertia.
Speed reduction, Servomotors operate more efficiently in higher speeds. Gearboxes help keep motors working at their optimal speeds.
Torque magnification. Gearboxes provide mechanical advantage by not merely decreasing rate but also increasing result torque.
The EP 3000 and our related products that use cycloidal gearing technology deliver the most robust solution in the most compact footprint. The main 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 includes a curved tooth profile rather than the more traditional involute tooth profile, which eliminates shear forces at any stage of contact. This design introduces compression forces, instead of those shear forces that would exist with an involute equipment mesh. That provides several performance benefits such as high shock load capacity (>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 period, which provides exceptional overhung load capabilities without requiring any extra expensive components.
Cycloidal advantages over other styles of gearing;
Capable of handling larger “shock” loads (>500%) of rating in comparison 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 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, in fact it is a perfect fit for applications in large industry such as oil & gas, major and secondary metal processing, industrial food production, metal reducing and forming machinery, wastewater treatment, extrusion apparatus, among others.