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Electrical drive technology Gearmotors Frequency inverters Servomotors Servo gear units AC motors, asynchronous motors Linear motors, linear movement Control Technology
What is a gear unit? How does a gear unit work? What types of gear unit are available? What we offer: The right gear unit for every application from our modular system What is a gear unit?

A gear unit is required to convert the torque and speed of an upstream electric motor so that they meet the technical drive requirements of an application. For that reason, the gear unit is the central component of a gearmotor.

How does a gear unit work?

Based on the design, size, and gear unit stages, a gear unit transforms the speed of a motor into steps up or steps down. The resulting speed ratio i between the input speed and output speed is therefore one of the most important characteristic values of a gear unit. How powerful a gear unit is and the loads that it can convey depends on its maximum torque, measured in the physical unit newton meters [Nm].

What types of gear unit are available?

Gear units are distinguished by the type of force flow that they transmit. As a result, there are three basic designs: Parallel-shaft gear units, right-angle gear units, and planetary gear units.

In parallel-shaft gear units and planetary gear units, the input and output shaft are positioned in one direction (on the same level). The power is therefore transmitted in a straight line. Parallel-shaft gear units are available in a helical gear unit or parallel-shaft helical gear unit mounting position.

Planetary gear units are a special form. With them, the power transmission is coaxial. In this case, the speed and torque of the input shaft – the central sun gear – are transmitted to an external annulus gear (on the output side) and transformed by three or more rotating planet gears. Their special feature: The input shaft and output shaft move in the same direction throughout this process. In combination with a servomotor planetary servo gearmotors provide particularly high dynamics and precision.

In right-angle gear units, in contrast, the drive shaft and output shaft are perpendicular to each other – with the result that the flow of force there is diverted at a right angle. There are three established versions of right-angle gear units. They include helical-bevel gear units, helical-worm gear units, and, exclusively from SEW‑EURODRIVE, the SPIROPLAN® right-angle gear unit.

What we offer: The right gear unit for every application from our modular system

With a portfolio including all of the conventional types of gear unit and a variety of different sizes, SEW‑EURODRIVE provides you with a comprehensive modular gear unit system. Combined with our modular motor system and other components, they provide millions of combination options. For practically every imaginable use case, you can therefore find a gearmotor that is perfectly tailored to your requirements, whether you choose one of our standard gear units, a servo gearmotor, a stainless steel gear unit, or an explosion-proof gear unit.

Standard gear unit

Do you need robust and reliable gear units for your production and logistics? If so, our standard gear units are your perfect solution. Choose between a variety of gear unit types in a huge number of sizes and with a maximum torque of up to 50,000 Nm. You can choose from:

R.. helical gear units F.. parallel-shaft helical gear units K.. helical-bevel gear units S..DR.. helical-worm gear units SPIROPLAN® right-angle gear units
Servo gear units

Does your application need powerful dynamics and high precision? Then our servo gearmotors are your ideal choice: Here too, you can use our modular system to combine a huge number of SEW gear units and motors to configure your own custom servo gearmotor. What we offer:

PF.. planetary servo gear unit BS.F.. helical servo gear unit
Stainless steel gear units

In cleaning-intensive hygiene areas of the food and drinks industry, gear units often come into contact with aggressive acids and alkalines. Our stainless steel gear units are robust, durable, and low-maintenance and specially tailored to such applications. The high-quality stainless steel housing with surfaces optimized for cleaning make this gear unit resistant to chemicals and dirt.

RES.. stainless steel helical gear unit KES.. stainless steel helical-bevel gear unit
Explosion-proof gear units

If plants and machines are exposed to environments with air and gas or air and dust mixtures due to the type of production involved, the strictest explosion protection regulations are applicable worldwide due to this hazard. Naturally, they also apply to the drive technology in question. With that in mind, most of our standard gear units and servo gear units are available in an explosion-proof design – which conforms with the most important regulations and standards for the global market, from ATEX to IECEx to HazLoc-NA®.

Can you solve the puzzle?

If you like solving problems, give our little puzzle a try :-)

A little tip:

The picture shows three of our standard gearmotors – parallel-shaft helical gearmotors, helical gearmotors and helical-bevel gearmotors. And each type stands for a particular number.

Once you’ve worked out these numbers, the solution is obvious, isn’t it?

On helical gearmotors, the input shaft (motor) and output shaft (gear unit) are located in a line. They are also called parallel-shaft gear units. Helical gearmotors are the most widely used traditional gearmotors.

Our helical gear unit / helical gearmotor stands for the number 4!

As their name suggests, parallel-shaft helical gear units also have a parallel-shaft design. Power transmission takes place parallel to the axis, but the output shaft is lower down. This makes parallel-shaft helical gearmotors ideal for confined spaces.

Our parallel-shaft helical gear unit / parallel-shaft helical gearmotor stands for the number 10!

Helical-bevel gear units form a 90°C angle. They belong to the "family" of right-angle gear units because their input and output shafts are arranged perpendicular to one another. This enables the power flow to be deflected at a right angle. Our helical-bevel gear units benefit from particularly wear-free gear components. This increases efficiency and thus saves on energy costs.

Our helical-bevel gear unit / helical-bevel gearmotor stands for the number 2!

Well? What’s the solution to the puzzle?

Have you worked it out? Congratulations!

The grand total is:


Short hint:

If no brackets are set, point calculation always takes precedence over dash calculation!

2 + 10 • 4 = 2 + 40 = 42