Planetary Gears: Principles Of Operation

Planetary gears are at the heart of modern engineering and are used in gearboxes that power everything from basic plant machinery to cutting-edge electric vehicles. The simple configuration of a central drive and orbiting gears was developed thousands of years ago to model the movements of the planets. Today, engineers use planetary gears in applications that demand high torque density, operational efficiency and durability. In this article, we explore the principles of operation, how planetary gears work, and where you might find them.



What Is A Planetary Gear Set?

A simple planetary gear set is made up of three main components:

1. The sun gear that sits in the centre (central gear).
2. Multiple planet gears.
3. The ring gear (outer gear).

The three components make up a stage within a planetary gearbox. For higher ratios we can offer double or triple stages.

Planetary gearboxes can be powered by either electric motors, hydraulic motors or petrol or diesel combustion engines.

The load from the sun gear is distributed to several planetary gears which can either be used to drive an outer ring or a shaft or spindle. The central sun gear takes a high-speed, low-torque input. It drives several rotating external gears which increases the torque.

The simple design is a highly efficient and effective way of transferring power from a motor to an output. Approximately 97% of the energy input is delivered as an output.


planetary gears diagram


Principles Of Operation

At Lancereal, we offer three different types of planetary gearbox, a wheel drive, shaft output and spindle output. Here’s what they are and how they work.


Wheel drive

Wheel drive

In a wheel drive planetary gearbox, the sun gear drives the surrounding planetary gears which are fixed to a carrier. When the sun gear is driven, the planet gears rotate the outer ring gear. The wheels can be mounted over the housing of the gearbox. By mounting the wheel directly to the gearbox, the size of the assembly can be minimised. Wheel drive planetary gears can deliver up to 332,000Nm torque.


Shaft Output

Shaft Output

In shaft drive gearboxes, the sun gear drives the surrounding planetary gears which are housed in a rotating carrier. The ring gear is held stationary with the rotating carrier delivering drive to the shaft.

The housing of the gearbox is fixed directly to the machine with the output being a rotating shaft. Our range of shaft output gears can deliver up to 113,000Nm torque.


Spindle Output

Spindle output gearbox

Spindle output planetary gearboxes work in the same was as shaft outputs; however, the output is supplied as a flange. Our spindle drive planetary gears can deliver up to 113,000Nm torque.


What Are Planetary Gears Used For?

Planetary gear sets can be used for a variety of purposes. At Lancereal, we provide planetary gear sets for use in industrial and mobile applications.

Our planetary gearboxes are used in:

  • Wheel drives
  • Track drives
  • Conveyors
  • Slew drives
  • Hoist drives
  • Mixing
  • Winch drives
  • Pumps
  • Coil tubing injectors
  • Auger & drilling drives
  • Cutter head drives

Planetary gear sets can be used in stages, which offer a variety of transmission ratio options that can be tailored to your requirements.


planetary gears 2


What Options Do I Have?

Our planetary gearboxes are available in 1-speed and 2-speed options. We’re able to provide single, double or triple stage units to suit any application.  We are also able to incorporate hydraulic, dynamic and electromagnetic braking within our range of planetary gearboxes.


How Do I Know What Planetary Gearbox I Need?

The choice of planetary gearbox, its size and gearing ratio should be defined by the outcome. It’s a careful balance between size, efficiency, performance and cost. At Lancereal, we have a consultative approach to design. We start each project by developing a deep understanding of the application, the speeds, torque and function of the machine.

We use our experience and insight to identify and supply a suitable planetary gear solution that’s cost-effective and reliable. Every gearbox we supply will deliver years of trouble-free performance. It’s this combination of engineering excellence and ongoing innovation that keeps Lancereal at the forefront of gearbox technology.



Get in touch

We are a leading specialist in the power transmission industry, please feel free to contact us regarding any planetary gearbox requirements. We have the in-house capability to adapt to all your requirements.

T: +44(0)1484 606040
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