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Electric Motors for Hydraulic Power Units: 0.37–22 kW, 1500 rpm, B35 Flange
Three-phase and single-phase electric motors driving hydraulic power units: 0.37 kW to 22 kW, 1500 rpm (4-pole), 220 V and 380 V, foot-and-flange B35 frame.
In a fixed hydraulic power unit the electric motor is the first link in the chain: it converts mains electricity into rotation, that rotation drives the pump, and the pump pressurises the oil. Selecting the motor correctly determines whether the unit works at all and how long it lasts.
The first value in the selection is power, calculated from what the pump will demand: power (kW) ≈ pressure (bar) × flow (l/min) ÷ 600 (with an allowance for overall efficiency). A system asking for 20 l/min at 100 bar needs roughly 3.3 kW; a 4 kW motor is chosen as the next step up. An undersized motor labours under load, draws current and trips the overload; oversizing does no harm but reduces efficiency at part load and adds cost.
The second value is speed. Hydraulic power units almost always use a 1500 rpm — that is, 4-pole — motor. Because pump flow is directly proportional to speed (flow ≈ displacement × speed), the motor speed must match the rated flow of the pump selected. A 3000 rpm motor draws twice the flow from the same pump, but the pump's suction capability and its service life may not suit that.
The third value is voltage and phase count. 380 V three-phase motors are the industry standard and are preferred in practice at every power above 1.5 kW. 220 V single-phase models are used in workshops and small units where no three-phase supply is available; at the same power they have a larger frame, cost more and have lower starting torque.
The fourth value is the mounting type, which governs installation. B35 means a frame with both feet and a flange: the motor sits on the chassis by its feet and bolts to the pump adaptor by its front flange. This is the standard choice for hydraulic power units, because the pump couples directly to the motor shaft and alignment has to be maintained. For pump and adaptor selection see the «Hydraulic Pumps» page.
Brands and standards in stock
Don't see the brand you're after? Ask anyway — electric motors products are made to standard, so different brands carrying the same standard are equivalents.
Electric Motors in stock — examples
| Product | Brand | Model / size | Item code |
|---|---|---|---|
| 0,37 kW 1500 d/d 380 V AC — AGM2EL 71 M 4B (B35) | Gamak | 0,37 kW · 380 V | GM.380.00,37 |
| 0,55 kW 1500 d/d 380 V AC — AGM2EL 80 M 4A (B35) | Gamak | 0,55 kW · 380 V | GM.380.00,55 |
| 0,75 kW 1500 d/d 380 V AC — AGM3EL 80 4B (B35) | Gamak | 0,75 kW · 380 V | GM.380.00,75 |
| 1,1 kW 1500 d/d 380 V AC — AGM3EL 90 S 4 (B35) | Gamak | 1,1 kW · 380 V | GM.380.01,10 |
| 1,5 kW 1500 d/d 380 V AC — AGM3EL 90 H 4B (B35) | Gamak | 1,5 kW · 380 V | GM.380.01,50 |
| 2,2 kW 1500 d/d 380 V AC — AGM3EL 100 L 4A (B35) | Gamak | 2,2 kW · 380 V | GM.380.02,20 |
| 3 kW 1500 d/d 380 V AC — AGM3EL 100 L 4B (B35) | Gamak | 3 kW · 380 V | GM.380.03,00 |
| 4 kW 1500 d/d 380 V AC Elektrik Motoru | Gamak | 4 kW · 380 V | GM.380.04,00 |
| 5,5 kW 1500 d/d 380 V AC Elektrik Motoru | Gamak | 5,5 kW · 380 V | GM.380.05,50 |
| 7,5 kW 1500 d/d 380 V AC Elektrik Motoru | Gamak | 7,5 kW · 380 V | GM.380.07,50 |
| 11 kW 1500 d/d 380 V AC Elektrik Motoru | Gamak | 11 kW · 380 V | GM.380.11,00 |
| 15 kW 1500 d/d 380 V AC — AGM3EL 160 L 4B (B35) | Gamak | 15 kW · 380 V | GM.380.15,00 |
| 18,5 kW 1500 d/d 380 V AC — AGM3EL 180 M 4A (B35) | Gamak | 18,5 kW · 380 V | GM.380.18,50 |
| 22 kW 1500 d/d 380 V AC — AGM3EL 180 L 4B (B35) | Gamak | 22 kW · 380 V | GM.380.22,00 |
| 0,37 kW 1500 d/d 220 V AC — MK21D 80 M 4A (B35) | Gamak | 0,37 kW · 220 V | GM.220.00.37 |
| 0,55 kW 1500 d/d 220 V AC — MK21D 80 M 4B (B35) | Gamak | 0,55 kW · 220 V | GM.220.00.55 |
| 0,75 kW 1500 d/d 220 V AC — MK21D 80 M 4C (B35) | Gamak | 0,75 kW · 220 V | GM.220.00.75 |
| 1,1 kW 1500 d/d 220 V AC — MK21D 90 S 4C (B35) | Gamak | 1,1 kW · 220 V | GM.220.01.10 |
| 1,5 kW 1500 d/d 220 V AC — MK21D 90 L 4D (B35) | Gamak | 1,5 kW · 220 V | GM.220.01.50 |
| 2,2 kW 1500 d/d 220 V AC — MK21D 100 L 4B (B35) | Gamak | 2,2 kW · 220 V | GM.220.02.20 |
| 3 kW 1500 d/d 220 V AC — MK21D 100 L 4C (B35) | Gamak | 3 kW · 220 V | GM.220.03.00 |
| Powerpack Elektrik Motoru 0,8 kW 24 V DC | Hydropack | 0,8 kW · 24 V DC | HR.HPP.DC24V-0.8 |
| Powerpack Elektrik Motoru 2,2 kW 24 V DC | Hydropack | 2,2 kW · 24 V DC | HR.HPP.DC24-2.2 |
This list is sorted by our highest-moving items and isn't the whole of our 23-item electric motors stock. If the size you need isn't listed, we very likely have it — just ask.
Frequently asked questions
How many kW do I need?
Motor power is calculated from what the pump will demand: power (kW) ≈ pressure (bar) × flow (l/min) ÷ 600. That formula includes an approximate allowance for efficiency. A system asking for 20 l/min at 100 bar needs roughly 3.3 kW, so the next standard size, 4 kW, is chosen. On systems running continuously at full load, going one size up is the safe option.
Why is 1500 rpm always used?
Pump flow is directly proportional to speed, and the rated flows of hydraulic pumps are generally quoted at 1500 rpm. A 4-pole (1500 rpm) motor also runs more quietly than a 2-pole one and does not strain the pump's suction capability. High speed increases the risk of cavitation at the pump inlet.
What does B35 mean?
B35 is the mounting designation for a motor that has both a footed and a flanged frame. The motor sits on the chassis by its feet and bolts to the pump adaptor by its front flange. It is the standard choice for hydraulic power units: because the pump couples to the motor shaft, misalignment has to be prevented by the flange.
220 V single-phase or 380 V three-phase?
If three-phase is available on site, 380 V is preferred: at the same power it gives a smaller frame, higher starting torque and better efficiency. 220 V single-phase models are used only where there is no three-phase supply, and generally remain reasonable up to about 3 kW.
The motor overload keeps tripping — what could cause it?
The most common cause is the system holding the motor at full load continuously: the pressure setting may be higher than needed, or the pump flow may be oversized for the motor. The second is cooling — if the rear fan cowl is blocked the windings overheat. The third is electrical: phase loss, low voltage, or an incorrectly set overload relay. Oil thickening in cold weather also raises the current on first start.
Get a quote for Electric Motors
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