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When replacing a 4 kW GAMAK electric motor, most of the work is about dimensions: the shaft must enter the coupling or pulley, the feet must sit on the base, the flange on its mating flange, and the cabling must suit the new terminal box. This article explains which dimensions decide at 4 kW, how to take them on the old motor and how DRG MOTOR compares them with catalogue values.
4 kW in the manufacturer's catalogue: 112M frame and 28×60 shaft
For 4 kW, GAMAK's technical catalogue names the four-pole IE3 aluminium motor AGM3EL 112 M 4a and the two-pole type as AGM3EL 112 M 2a; both are shown in a 112M frame with a 28×60 mm shaft. In that catalogue, the cast-iron 2- and 4-pole tables start at 5.5 kW; the types at this power are listed in the aluminium-frame tables. The dimension tables are based on IEC 60072-1. Still, check the frame code on your nameplate; an older or special order may differ.
Shaft: diameter, length and key
The shaft size is the firmest limit; the coupling or pulley hub is machined to that diameter. On the DRG DRG-112M-4 and DRG-112M-2, the shaft is 28×60 mm, key width 8 mm and shaft-end thread M10X22. Moving to the 1000 class changes the picture: the 4 kW DRG-132M1-6 has a 132M frame and a 38×80 mm shaft. The shaft growing from 28 to 38 mm at the same 4 kW clearly shows that the same power value alone does not make a replacement possible. When measuring shaft length, take it from the shoulder to the end and note the length of the keyway too.
Frame: foot dimensions and flange
For foot mounting (B3), shaft height H, foot hole spacing A × B and dimension C decide; C sets the coupling gap and the motor's position on the base. For flange mounting (B5), flange outer diameter P, spigot diameter N and pitch circle M must match the mating flange. The DRG catalogue shows a notable detail: frames 100L and 112M have the same B5 flange (P 250, N 180, M 215 mm) and the same 28×60 shaft, but their shaft heights are 100 and 112 mm. So in a flange-mounted application there may be a choice between the two frames, whereas on a foot-mounted one the 12 mm height difference would upset coupling alignment. DRG offers a B14 small-flange option, with dimensions confirmed at order.
| Dimension | What it means | DRG-112M-4 (mm) | How to take it on the old motor |
|---|---|---|---|
| D × E | Shaft diameter × shaft length | 28 × 60 | Caliper for diameter, shoulder to end for length |
| F / GA | Key width / shaft height including key | 8 / 31 | Key and coupling hub |
| H, A × B, K | Shaft height, foot hole spacing, hole | 112; 190 × 140; 4–Φ12 | Measured from the base surface |
| C | Front foot hole to shaft shoulder | 70 | Sets the coupling gap |
| P / N / M / S | B5 flange outer diameter, spigot, pitch circle, hole | 250 / 180 / 215 / 14.5 | From the mating flange |
| L / AC | Overall length / frame diameter | 394 / 230 | Space available in the machine |
The table shows DRG catalogue values; they should be checked by comparing them with the corresponding dimensions on your old motor. Full dimensioned sketches can be downloaded from DRG motor technical drawings.
Recording your readings under these same headings and sharing them over WhatsApp together with the plate photo lets DRG MOTOR check each line in turn.
Connection: terminals, voltage and cable entry
In the DRG MOTOR online store, models up to 3 kW are listed as 230/400 V and models of 4 kW and above as 400/690 V; any special voltage or different frequency requirement should be stated separately. If your old GAMAK electric motor's nameplate shows a different voltage pair, whether the starting arrangement in the panel suits the new motor must be decided by qualified technical personnel. The cable entry of the DRG-112M-4 is 2 × M32×1,5; check that glands and cable cross-section match. Rated current at 400 V is 7.95 A.
DRG options that can be assessed
DRG Motor is a manufacturer, supplier and seller of electric motors. Models whose dimensions you can compare for 4 kW:
- DRG-112M-4 – 112M, 1450 rpm, shaft 28×60
- DRG-112M-2 – 112M, 2905 rpm, shaft 28×60
- DRG-132M1-6 – 132M, 968 rpm, shaft 38×80
Further aluminium-housed motors: Aluminum Housing Three Phase Induction Motor. Complete range: DRG online store.
Frequently asked questions
Can I use a motor with a different shaft height by shimming it?
That is a mounting decision and must be assessed for base strength, alignment and vibration. Our suggestion is to look first at options with the same H dimension.
My old motor has a B14 flange; how should I send its dimensions?
List four values: outside flange diameter, centring spigot, bolt circle and tapped hole size. DRG confirms B14 sizes per order, so your figures become the reference.
How precise should the measurements be?
Measuring the shaft diameter with a caliper and other dimensions to the millimetre is a sufficient start. If a value looks doubtful, add a photo.
Dimensions and information to send DRG MOTOR
- Nameplate photo, type code, frame code (e.g. 112M)
- Shaft diameter × length, key width, shaft-end thread
- For foot mounting: H, A × B, C and foot hole diameter
- For flange mounting: P, N, M and hole size; whether B5 or B14
- Voltage pair, current and nominal speed on the nameplate
- Cable entry and gland size used
- Machine type and transmission element (coupling, pulley, gearbox)
With these measurements in hand, DRG MOTOR can match shaft, frame and fixing points against its catalogue and tell you which model is worth a closer look for your machine.
Contact: WhatsApp · quote list · +90 (542) 666 11 11 · info@drgmotor.com · contact page
Technical Sources
- GAMAK — Teknik Katalog (TR), Turkish-language technical catalogue — Standards and recommendations (Standartlar ve Tavsiyeler) — printed page 18 (PDF page 18).
- GAMAK — Teknik Katalog (TR), Turkish-language technical catalogue — Three-phase standard asynchronous motors, aluminium-frame performance tables (2 and 4 poles) — printed pages 69–70 (PDF pages 69–70).
- GAMAK — Teknik Katalog (TR), Turkish-language technical catalogue — Three-phase standard asynchronous motors, cast-iron-frame performance tables (2 and 4 poles) — printed pages 76–77 (PDF pages 76–77).
- GAMAK — Teknik Katalog (TR), Turkish-language technical catalogue — Three-phase asynchronous motors / motor dimensions: aluminium motors, foot-mounted motor (IEC 60072-1) – B3 — printed page 88 (PDF page 88).
