Cycloidal gearboxes
Cycloidal gearboxes or reducers consist of 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 supporters in the casing. Cylindrical cam followers become teeth on the inner gear, and the amount of cam fans exceeds the number of cam lobes. The next track of compound cam lobes engages with cam followers on the result shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus raising torque and reducing velocity.
Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking phases, as in regular planetary gearboxes. The gearbox’s compound decrease and can be calculated using:
where nhsg = the amount 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 are based on gear geometry, heat treatment, and finishing procedures, cycloidal variations share simple design principles but generate cycloidal motion in different ways.
Planetary gearboxes
Planetary gearboxes are made up of three simple force-transmitting elements: a sun gear, three or even more satellite or planet 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, subsequently, rotate in the stationary ring equipment. The ring equipment is area of the gearbox casing. Satellite gears rotate on rigid shafts linked to the planet carrier and trigger the earth carrier to rotate and, thus, turn the output shaft. The gearbox provides result shaft higher torque and lower rpm.
Planetary gearboxes generally have one or two-gear stages for reduction ratios which range from 3:1 to 100:1. A third stage can be added for even higher ratios, nonetheless it is not common.
The ratio of a planetary gearbox is calculated using the next 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 first consider the precision needed in the application form. If backlash and positioning precision are necessary, then cycloidal gearboxes provide best choice. Removing backlash can also help the servomotor manage high-cycle, high-frequency moves.
Next, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and speed for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide greatest torque density, weight, and precision. In fact, 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 required ratio goes Cycloidal gearbox beyond 100:1, cycloidal gearboxes hold advantages because stacking stages is unnecessary, so the gearbox can be shorter and less expensive.
Finally, consider size. The majority of manufacturers provide square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes grow in length from solitary to two and three-stage styles as needed gear 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 larger in diameter for the same torque but are not for as long. The compound decrease cycloidal gear teach handles all ratios within the same package size, so higher-ratio cycloidal gear boxes become even shorter than planetary versions with the same ratios.
Backlash, ratio, and size provide engineers with an initial gearbox selection. But selecting the most appropriate gearbox also consists of bearing capability, torsional stiffness, shock loads, environmental conditions, duty cycle, and life.
From a mechanical perspective, gearboxes have grown to be somewhat of accessories to servomotors. For gearboxes to perform properly and provide engineers with a balance 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 although both are epicyclical reducers, the differences between the majority of planetary gearboxes stem more from equipment geometry and manufacturing processes rather than principles of procedure. But cycloidal reducers are more different and share little in common with one another. There are advantages in each and engineers should think about the strengths and weaknesses when selecting one over the various other.
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
Great things about 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 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 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 significantly less than four situations its own inertia.
Speed reduction, Servomotors run more efficiently at higher speeds. Gearboxes help to keep motors working at their optimal 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 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 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 gets rid of shear forces at any point of contact. This design introduces compression forces, instead of those shear forces that would can be found with an involute gear mesh. That provides several performance benefits such as for example high shock load capability (>500% of rating), minimal friction and put on, lower mechanical service elements, among many others. The cycloidal design also has a huge output shaft bearing period, which provides exceptional overhung load features without requiring any additional expensive components.
Cycloidal advantages over other 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 engine for longer service life
Just ridiculously rugged as all get-out
The overall EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP is the most reliable reducer in the industrial marketplace, in fact it is a perfect match for applications in large industry such as for example oil & gas, primary and secondary metal processing, industrial food production, metal reducing and forming machinery, wastewater treatment, extrusion devices, among others.
