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 track of the cycloidal cam lobes engages cam followers in the housing. Cylindrical cam followers become teeth on the inner gear, and the number of cam followers exceeds the number of cam lobes. The next track of compound cam lobes engages with cam followers on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the result shaft, thus increasing torque and reducing rate.
Compound cycloidal gearboxes provide ratios ranging from as low as 10:1 to 300:1 without stacking stages, as in regular planetary gearboxes. The gearbox’s compound decrease 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 swiftness output shaft (flange).
There are several commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations derive from gear geometry, heat therapy, and finishing procedures, cycloidal variations share simple design concepts but generate cycloidal movement in different ways.
Planetary gearboxes are made up of three simple force-transmitting elements: a sun gear, three or more satellite or planet gears, and an internal ring gear. In an average gearbox, the sun gear attaches to the input shaft, which is linked to the servomotor. The sun gear transmits engine rotation to the satellites which, in turn, rotate in the stationary ring equipment. The ring gear is part of the gearbox housing. Satellite gears rotate on rigid shafts linked to the earth carrier and trigger the earth carrier to rotate and, thus, turn the result shaft. The gearbox Cycloidal gearbox provides output shaft higher torque and lower rpm.
Planetary gearboxes generally have single or two-equipment 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 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 among cycloidal and planetary gearboxes, engineers should initial consider the precision needed in the application. If backlash and positioning accuracy are necessary, then cycloidal gearboxes provide most suitable choice. Removing backlash may also help the servomotor manage 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 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 can be used. However, if the required ratio goes beyond 100:1, cycloidal gearboxes hold advantages because stacking levels is unnecessary, so the gearbox could be shorter and less costly.
Finally, consider size. Many manufacturers offer 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 greater than 100:1, respectively.
Conversely, cycloidal reducers are larger in diameter for the same torque yet are not as long. The compound reduction cycloidal gear train handles all ratios within the same package deal size, so higher-ratio cycloidal gear boxes become even shorter than planetary variations with the same ratios.
Backlash, ratio, and size provide engineers with a preliminary gearbox selection. But selecting the most appropriate gearbox also requires bearing capacity, 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 execute properly and provide engineers with a stability of performance, life, 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 are appropriate in virtually any industry that uses servos or stepper motors. And even though both are epicyclical reducers, the variations between many planetary gearboxes stem more from gear geometry and manufacturing processes instead of principles of procedure. But cycloidal reducers are more different and share little in common with each other. There are advantages in each and engineers should think about the strengths and weaknesses when choosing 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 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 necessity 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 powerful situations. Servomotors can only control up to 10 times their personal inertia. But if response period is critical, the engine should control less than four situations 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 acceleration 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 main power train is made up of an eccentric roller bearing that drives a wheel around a set of internal pins, keeping the decrease high and the rotational inertia low. The wheel includes a curved tooth profile instead of the more traditional involute tooth profile, which eliminates shear forces at any stage of contact. This style introduces compression forces, instead of those shear forces that would can be found with an involute gear mesh. That provides numerous overall performance benefits such as for example high shock load capability (>500% of ranking), minimal friction and put on, lower mechanical service elements, among numerous others. The cycloidal style also has a large output shaft bearing span, which gives exceptional overhung load features without requiring any extra 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 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 is the most dependable reducer in the commercial marketplace, in fact it is a perfect match for applications in weighty industry such as for example oil & gas, main and secondary metal processing, commercial food production, metal reducing and forming machinery, wastewater treatment, extrusion tools, among others.