planetary gear reduction

Many “gears” are used for automobiles, however they are also used for many other machines. The most typical one may be the “tranny” that conveys the power of engine to tires. There are broadly two functions the transmission of an automobile plays : one is to decelerate the high rotation swiftness emitted by the engine to transmit to tires; the additional is to change the reduction ratio relative to the acceleration / deceleration or traveling speed of an automobile.
The rotation speed of an automobile’s engine in the overall state of generating amounts to at least one 1,000 - 4,000 rotations each and every minute (17 - 67 per second). Since it is impossible to rotate tires with the same rotation acceleration to run, it is necessary to lessen the rotation speed utilizing the ratio of the amount of gear teeth. Such a role is called deceleration; the ratio of the rotation swiftness of engine and that of wheels is named the reduction ratio.
Then, why is it necessary to alter the reduction ratio relative to the acceleration / deceleration or driving speed ? This is because substances require a large force to start moving however they do not require such a big force to keep moving once they have began to move. Automobile can be cited as a good example. An engine, however, by its nature can’t so finely modify its output. For that reason, one adjusts its output by changing the decrease ratio employing a transmission.
The transmission of motive power through gears very much resembles the principle of leverage (a lever). The ratio of the number of teeth of gears meshing with one another can be considered as the ratio of the distance of levers’ arms. That's, if the decrease ratio is huge and the rotation rate as output is lower in comparison to that as input, the power output by transmitting (torque) will be huge; if the rotation quickness as output isn't so low in comparison to that as input, on the other hand, the energy output by transmitting (torque) will be small. Thus, to improve the decrease ratio utilizing transmission is much akin to the theory of moving things.
After that, how does a tranny modify the reduction ratio ? The answer is based on the mechanism called a planetary gear mechanism.
A planetary gear system is a gear system comprising 4 components, namely, sunlight gear A, several world gears B, internal gear C and carrier D that connects world gears as observed in the graph below. It includes a very complex structure rendering its design or production most difficult; it can recognize the high reduction ratio through gears, however, it is a mechanism suited to a reduction system that requires both little size and high planetary gear reduction performance such as transmission for automobiles.
In a planetary gearbox, many teeth are engaged at once, that allows high speed decrease to be achieved with relatively small gears and lower inertia reflected back again to the motor. Having multiple teeth discuss the load also enables planetary gears to transmit high levels of torque. The mixture of compact size, large speed reduction and high torque transmission makes planetary gearboxes a popular choice for space-constrained applications.
But planetary gearboxes perform involve some disadvantages. Their complexity in style and manufacturing can make them a far more expensive option than other gearbox types. And precision manufacturing is extremely important for these gearboxes. If one planetary gear is put closer to sunlight gear compared to the others, imbalances in the planetary gears can occur, leading to premature wear and failure. Also, the compact footprint of planetary gears makes heat dissipation more difficult, so applications that run at very high speed or encounter continuous operation may require cooling.
When utilizing a “standard” (i.electronic. inline) planetary gearbox, the motor and the driven equipment must be inline with one another, although manufacturers offer right-angle designs that include other gear sets (often bevel gears with helical tooth) to supply an offset between the input and output.
Input power (max)27 kW (36 hp)
Input speed (max)2800 rpm2
Output torque (intermittent)12,880 Nm(9,500 lb-ft)
Output torque (continuous)8,135 Nm (6,000 lb-ft)
1 Actual ratio would depend on the drive configuration.
2 Max input speed related to ratio and max output speed
3 Max radial load placed at optimum load position
4 Weight varies with configuration and ratio selected
5 Requires tapered roller planet bearings (not available with all ratios)
Approximate dry weight100 -181 kg (220 - 400 lb)4
Radial load (max)14,287kg (31,500 lb)3
Drive typeSpeed reducer
Hydraulic engine input SAE C or D hydraulic
Precision Planetary Reducers
This standard range of Precision Planetary Reducers are perfect for use in applications that demand powerful, precise positioning and repeatability. They were specifically developed for make use of with state-of-the-art servo motor technology, providing tight integration of the engine to the unit. Design features include installation any servo motors, standard low backlash, high torsional stiffness, 95 to 97% efficiency and quiet running.
They can be purchased in nine sizes with decrease ratios from 3:1 to 600:1 and output torque capacities up to 16,227 lb.ft. The output can be provided with a good shaft or ISO 9409-1 flange, for installation to rotary or indexing tables, pinion gears, pulleys or other drive components without the need for a coupling. For high precision applications, backlash levels down to 1 arc-minute are available. Right-angle and input shaft versions of the reducers are also available.
Common applications for these reducers include precision rotary axis drives, traveling gantries & columns, materials handling axis drives and electronic line shafting. Industries served include Material Handling, Automation, Aerospace, Machine Tool and Robotics.
Unit Design &
Construction
Gearing: Featuring case-hardened & ground gearing with minimal wear, low backlash and low noise, making them the the majority of accurate and efficient planetaries available. Standard planetary style has three world gears, with a higher torque version using four planets also obtainable, please see the Reducers with Output Flange chart on the Unit Ratings tab beneath the “+” unit sizes.
Bearings: Optional output bearing configurations for software specific radial load, axial load and tilting moment reinforcement. Oversized tapered roller bearings are regular for the ISO Flanged Reducers.
Housing: Single piece metal housing with integral band gear provides higher concentricity and remove speed fluctuations. The housing can be installed with a ventilation module to increase insight speeds and lower operational temperatures.
Output: Available in a solid shaft with optional keyway or an ISO 9409-1 flanged interface. We offer an array of standard pinions to install right to the output design of your choice.
Unit Selection
These reducers are usually selected predicated on the peak cycle forces, which usually happen during accelerations and decelerations. These cycle forces depend on the powered load, the swiftness vs. period profile for the cycle, and any other external forces functioning on the axis.
For application & selection assistance, please call, fax or email us. The application info will be examined by our engineers, who will recommend the best solution for your application.
Ever-Power Automation’s Gearbox products offer high precision in affordable prices! The Planetary Gearbox item offering contains both In-Line and Right-Position configurations, built with the design goal of offering a cost-effective gearbox, without sacrificing quality. These Planetary Gearboxes are available in sizes from 40mm to 180mm, well suited for motors ranging from NEMA 17 to NEMA 42 and larger. The Spur Gearbox collection provides an efficient, cost-effective choice compatible with Ever-Power Automation’s AC Induction Gear Motors. Ever-Power Automation’s Gearboxes can be found in up to 30 different gear ratios, with torque ratings up to 10,488 in-pounds (167,808 oz-in), and so are compatible with most Servo,
SureGear Planetary Gearboxes for Little Ever-Power Motors
The SureGear PGCN series is a good gearbox value for servo, stepper, and other motion control applications requiring a NEMA size input/output interface. It provides the best quality designed for the price point.
Features
Wide variety of ratios (5, 10, 25, 50, and 100:1)
Low backlash of 30 arc-min or less
20,000 hour service life
Free of maintenance; requires no additional lubrication
NEMA sizes 17, 23, and 34
Includes hardware for mounting to SureStep stepper motors
Optional shaft bushings available for mounting to other motors
1-year warranty
Applications
Material handling
Pick and place
Automation
Packaging
Additional motion control applications requiring a Ever-Power input/output
Spur gears are a type of cylindrical gear, with shafts that are parallel and coplanar, and tooth that are straight and oriented parallel to the shafts. They’re arguably the easiest and most common type of gear - easy to manufacture and ideal for a range of applications.
One’s tooth of a spur gear have got an involute profile and mesh one particular tooth simultaneously. The involute type implies that spur gears simply generate radial forces (no axial forces), however the approach to tooth meshing causes high pressure on the gear the teeth and high noise creation. Because of this, spur gears are usually used for lower swiftness applications, although they can be utilized at nearly every speed.
An involute products tooth carries a profile this is the involute of a circle, which means that since two gears mesh, they speak to at an individual point where in fact the involutes meet. This aspect motions along the tooth areas as the gears rotate, and the kind of force ( known as the line of activities ) is certainly tangent to both foundation circles. Hence, the gears adhere to the fundamental regulation of gearing, which statements that the ratio of the gears’ angular velocities must stay continuous throughout the mesh.
Spur gears could possibly be produced from metals such as steel or brass, or from plastics such as nylon or polycarbonate. Gears manufactured from plastic produce less sound, but at the trouble of power and loading capability. Unlike other devices types, spur gears don’t encounter high losses because of slippage, therefore they often times have high transmission performance. Multiple spur gears can be utilized in series ( referred to as a equipment teach ) to realize large reduction ratios.
There are two primary types of spur gears: external and internal. Exterior gears possess one's teeth that are cut externally surface area of the cylinder. Two external gears mesh with one another and rotate in reverse directions. Internal gears, on the other hand, have tooth that are cut inside surface of the cylinder. An exterior gear sits in the internal equipment, and the gears rotate in the same direction. Because the shafts are positioned closer together, internal gear assemblies are smaller sized than external gear assemblies. Internal gears are primarily used for planetary gear drives.
Spur gears are generally viewed as best for applications that want speed reduction and torque multiplication, such as ball mills and crushing gear. Types of high- velocity applications that make use of spur gears - despite their high noise levels - include consumer appliances such as washers and blenders. And while noise limits the use of spur gears in passenger automobiles, they are generally used in aircraft engines, trains, and even bicycles.