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June 18, 2020

Cycloidal gearboxes
Cycloidal gearboxes or reducers contain four simple components: a high-speed input shaft, an individual 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 an eye on the cycloidal cam lobes engages cam followers in the casing. Cylindrical cam followers act as teeth on the internal gear, and the number of cam supporters exceeds the number of cam lobes. The next track of substance cam lobes engages with cam supporters on the result shaft and transforms the cam’s eccentric rotation into concentric rotation of the result shaft, thus raising torque and reducing velocity.

Compound cycloidal gearboxes provide ratios ranging from only 10:1 to 300:1 without stacking levels, as in regular 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 slower 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 procedures, cycloidal variations share fundamental design principles but generate cycloidal motion in different ways.
Planetary gearboxes
Planetary gearboxes are made of three basic force-transmitting elements: a sun gear, three or more satellite or world gears, and an interior ring gear. In a typical gearbox, the sun gear 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 equipment. The ring equipment is area of the gearbox housing. Satellite gears rotate on rigid shafts linked 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 even higher ratios, nonetheless it is not common.

The ratio of a planetary gearbox is calculated using the following formula:where nring = the amount 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 1st consider the precision needed in the application form. If backlash and positioning accuracy are necessary, then cycloidal gearboxes provide best choice. Removing backlash may also help the servomotor handle high-cycle, high-frequency moves.

Next, 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 provide greatest torque density, weight, and precision. In fact, not many cycloidal reducers provide 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 levels is unnecessary, therefore the gearbox can be shorter and less expensive.
Finally, consider size. Most manufacturers provide square-framed planetary gearboxes that mate specifically with servomotors. But planetary gearboxes develop in length from one to two and three-stage styles as needed equipment ratios go from less than 10:1 to between 11:1 and 100:1, and to greater than 100:1, respectively.

Conversely, cycloidal reducers are bigger 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 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 selecting the most appropriate gearbox also involves bearing capability, torsional stiffness, shock loads, environmental conditions, duty routine, 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, existence, and value, sizing and selection ought to be determined from the load side back again 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 even though both are epicyclical reducers, the variations between most planetary gearboxes stem more from equipment geometry and manufacturing procedures instead of principles of operation. 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.

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 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 choosing the gearbox is to control inertia in highly powerful circumstances. Servomotors can only control up to 10 times their very own inertia. But if response time is critical, the motor should control less than four times its own inertia.

Speed reduction, Servomotors operate more efficiently in higher speeds. Gearboxes help to keep motors operating at their optimum speeds.

Torque magnification. Gearboxes offer mechanical advantage by not only decreasing speed 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 made up of an eccentric roller bearing that drives a wheel Cycloidal gearbox 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 design introduces compression forces, rather than those shear forces that could exist with an involute equipment mesh. That provides several performance benefits such as for example high shock load capability (>500% of rating), minimal friction and use, lower mechanical service factors, among numerous others. The cycloidal style also has a big output shaft bearing period, which provides exceptional overhung load capabilities without requiring any additional expensive components.

Cycloidal advantages over other 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 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 because all get-out
The entire EP design proves to be extremely durable, and it needs minimal maintenance following installation. The EP is the most reliable reducer in the industrial marketplace, in fact it is a perfect fit for applications in large industry such as for example oil & gas, major and secondary steel processing, commercial food production, metal slicing and forming machinery, wastewater treatment, extrusion apparatus, among others.