Planetary Gear Reducer
The Planetary Gear Reducer product lines offer the precision required, at prices that make them an affordable choice! Planetary Gear Reducer products are available in sizes from 40 mm to 120mm, which is ideal for motors ranging from NEMA 17 to larger than NEMA 42. The Planetary Gear Reducer is built with the design goal of offering a cost-effective product without sacrificing quality. Prices appear on this web site, with all the information required to select the perfect Planetary Gear Reducer product for your application.
Spur Gear Reducer
The Spur Gear Reducer product lines offer the precision required, at prices that make them an affordable choice! Spur Gear Reducer products are available in sizes from 60 mm to 90mm.The Spur Gear Reducer is built with the design goal of offering a cost-effective product without sacrificing quality. We have a wide range of ratios to fit your application. Prices appear on this web site, with all the information required to select the perfect Planetary Gear Reducer product for your application.
  • Planetary Gear Reducer Basics
  • What is a Planetary Gear Reducer?
  • Planetary Gear Reducer Cost
  • How a Planetary Gear Reducer Works
  • Planetary Gear Reducer Advantages
  • Planetary Gear Reducer Selection

A Planetary Gear Reducer is defined as a set of gears, shafts and bearings that are enclosed in a housing unit. The way the gears, shafts, and bearings are arranged resemble solar system because one or more of the plant gears orbit around a sun gear.

A Planetary Gear Reducer is a set of gears, shafts, and bearings that are enclosed in a housing and are arranged in a way that resemble a solar system, (thus the name planetary) with one or more planet gears orbiting around a sun gear. They convert input speed (typically provided by an electric motor) into a lower output speed while correspondingly creating higher torque. In other words, gear-boxes reduce RPM, turning it into power for use in low-RPM high-torque applications. Gearboxes come in different arrangements including planetary, bevel, cycloid, helical, harmonic, spur, and worm. Our focus here is on the planetary type of gear system.

The Planetary Gear Reducer come in many sizes and torque capacities, with varying speed ratios depending upon configuration. These Planetary Gear Reducer products that are pictured above are approximately 60 mm to 2.4 inches in size, and produce output torque ranging roughly from 2,000 to 25,000 ounce-inch.

A much larger Planetary Gear Reducer exists for industrial processes, providing output torque in excess of 500,000 ounce-inch. The focus of this website, however, is on these smaller Planetary Gear Reducer types.

The input power to these small Planetary Gear Reducer products come from small electric motors (either a stepper motor, DC motor, or servo motor). Small motors are found in many household devices such as fans, clocks, timers, cassette players, printers, computer disc drives, etc.

The price of planetary gea reducer varies based on many factors. For backlash in the 30 arc-minute range, the cost for a gear reducer might be as low as $100. For low backlash gearboxes under 5 arc-minutes they will cost quite a bit more. Below is a listing of planetary gear reducer products offered by Anaheim Automation - they list comprehensive specs and prices on their website with web discounts.

Model Cost Size Backlash  Ratio Range
gear motor $30.00 under 40 mm varies 3 to 512
GBPH-060 $195.00 60 mm square (Fits NEMA 23) 10 arc-min 3 to 512
GBPH-090 $295.00 90 mm square (Fits NEMA 34) 8 arc-min 3 to 1000
GBPN-120 $457.00 120 mm square (Fits NEMA 42) 9 arc-min 3 to 512


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Planetary Gear Reducer Article

The Planetary Gear Reducer system has 3 main components: a central sun gear, a planet carrier (carrying one or more planet gears),and an annulus (an outer ring). The central sun gear is orbited by planet gears (of the same size) that are mounted to the planet carrier. The planet gears are meshed with the sun gear. An outer ring (the annulus) has teeth facing inward that also mesh with the planet gears.

There are several configurations for Planetary Gear Reducer systems. Typical configurations require that out of the 3 components: one is the input, one is the output, and one is stationary.

For example, one configuration is where the sun gear is the input , the annulus is the output, and the planet carrier is stationary. In this configuration, the input shaft rotates the sun gear. The planet gears rotate on their own axes, simultaneously applying a torque to the rotating planet carrier, that in turn applies torque to the output shaft (which in this case is the annulus).

The rate at which the gears rotate (gear ratio) is determined by the number of teeth in each gear. The torque (power output) is determined by both the number of teeth and by which component in the planetary system is stationary.

The Planetary Gear Reducer arrangement is an ingenious engineering design that offers many advantages over traditional gearbox arrangements. One advantage is its unique combination of both compactness and outstanding power transmission efficiencies. Typical efficiency loss in a Planetary Gear Reducer arrangement is only 3% per stage. This type of efficiency ensures that a high proportion of the energy being input into the Planetary Gear Reducer is multiplied and transmitted into torque, rather than being wasted on mechanical losses inside the Planetary Gear Reducer.

Another advantage of the Planetary Gear Reducer arrangement is load distribution. Because the load being transmitted is shared between multiple planets, torque capability is greatly increased. The more planets in the system, the greater load ability and the higher the torque density.

The Planetary Gear Reducer arrangement also creates greater stability (it's a balanced system) and increased rotational stiffness. Disadvantages of the Planetary Gear Reducer arrangement include design complexity and accessibility issues.

In the drawing above, the Fixed Axis Gear System is the traditional arrangement where a pinion is driving one large gear on a parallel shaft. In the Planetary Gear Reducer System arrangement, one or more gears (planet gears) surround the pinion (sun gear). The two systems above have approximately the same ration and same volume. However, the Planetary Gear Reducer system has 3 times higher torque density and 3 times higher stiffness due to the increased number of gear contacts.

Fixed Axis Gear System:
•Volume = 1, Torque = 1, Stiffness = 1
Planetary Gear Reducer System:
•Volume =1, Torque = 3, Stiffness = 3
Other gearbox arrangements (as mentioned previously) include bevel, cycloid, helical, harmonic, spur, and worm.



It's important to know certain performance specifications when selecting a Planetary Gear Reducer, such as: input speed (this determines the gear ratio), output speed, and output torque required.