Motor Dimensions and Mechanical Connections

The dimensions that connect a motor to a machine

Even with the right power and speed, a motor that cannot be mounted stops the job. This section is for readers who search by mechanical connection: they have a coupling, a pulley, a gearbox input or a flanged machine seat and want the motor that fits it. The articles start from the shaft diameter, the B5 flange, the gearbox input flange (PAM) and flange motor selection at higher powers.

What this section covers

• Motor by shaft diameter: which DRG frames and models exist for each shaft size from 11 mm to 100 mm, together with shaft length and key width.
• B5 flange motors at higher power: flange dimensions in the 30–55 kW and 75–315 kW ranges, the shaft difference between 2- and 4-pole models, and the limits of carrying a motor on its flange.
• Gearbox input: what a PAM input means and which details to read from a worm gearbox nameplate before choosing the motor.

Reading dimensions correctly

On a flange, four values are checked separately: outer diameter (P), spigot diameter (N), pitch circle (M) and hole diameter (S). On the shaft, diameter (D), length (E) and key width (F) go together. In the same frame the shaft may change with the number of poles, and motors of the same power but different speed may sit in different frames. A gearbox size code (030, 063, 090…) does not by itself give a motor dimension; the input adaptor, input bore and ratio must be read from the gearbox maker's documentation. Small flange (B14) dimensions are not tabulated here; send your measurements for confirmation.

Related tables

The electrical side is covered by the motor current chart and the electric motor calculator. For model lists frame by frame, see the section on electric motors by IEC frame size.

Seeing the matching motors

Each article ends with product cards of the DRG motors that match the dimension; open a card for the current price and technical data. All models are in the online shop, and the product family is on the three-phase asynchronous electric motors page. Send your shaft, flange or gearbox input size on WhatsApp and we will compare it with the data and identify the model with you.