A 400W gear motor is the point where a small drive stops being small. Below it, everything runs on single-phase power, a 12–15 mm output shaft and a frame light enough to lift by hand. At 400W the drive becomes three-phase only, the shaft steps up to 22 mm, the unit weighs around 12 kg, and the starter, the cable and the mounting plate all change with it. Buyers who treat 400W as “a bigger 90W” are the ones who discover the difference after the machine is built.
This guide covers what actually changes at 400W, how to calculate the output torque you will get at each ratio, what the step up from a small frame forces you to re-check, and how to decide between 400W and 750W before you commit to a layout.
The power figure is the least interesting part of the change. Five other specifications move at the same time, and each of them has consequences for the machine design.
| Item | 90W small frame | 400W medium frame | Consequence |
|---|---|---|---|
| Supply | 1-phase 110 V / 220 V, or 3-phase 380 V | 3-phase 220 V / 380 V only | No single-phase option; site must have three-phase distribution |
| Run capacitor | Required on single-phase models | None | One less wear item, no capacitor-induced torque dip |
| Trục ra | 12–15 mm typical | 22 mm standard | Different coupling, sprocket and bore; existing parts will not fit |
| Starting current | Modest, often within a domestic circuit | 4–7 times full load current on direct-on-line start | Needs a proper starter, overload relay and cable sizing |
| Mass | 3–5 kg | Around 12–13 kg | Mounting plate, bracket stiffness and handling change |
| Mounting | Flange or foot, compact pattern | Vertical or horizontal configuration, larger bolt pattern | Layout must be decided before ordering, not after |
That table is the real content of a 400W selection. The motor produces 400W and it is either 220 V three-phase or 380 V three-phase; almost every project problem at this power level comes from the five rows underneath that fact.
The product page publishes power, shaft diameter, voltage and mounting, but output torque depends on the ratio you select, so it has to be calculated rather than looked up. The standard relationship is:
Output torque (N·m) = 9550 × P (kW) × η / n (r/min)
where P = 0.4 kW
η = gearbox efficiency, typically 0.85–0.92 for a 2–3 stage reduction
n = output speed = motor rated speed ÷ ratioUsing a 4-pole motor at about 1400 r/min and an efficiency of 0.90, the calculated figures look like this.
| Tỷ lệ | Output speed at 50 Hz | Calculated output torque (η = 0.90) |
|---|---|---|
| 5:1 | 280 r/min | 12.3 N·m |
| 10:1 | 140 r/min | 24.6 N·m |
| 15:1 | 93 r/min | 37.0 N·m |
| 20:1 | 70 r/min | 49.1 N·m |
| 30:1 | 47 r/min | 73.2 N·m |
| 50:1 | 28 r/min | 122.8 N·m |
| 60:1 | 23 r/min | 149.5 N·m |
| 100:1 | 14 r/min | 245.6 N·m |
Two qualifications keep this table honest. First, it is the theoretical capability of a 400W input at 90% efficiency — the gearbox’s own allowable load rating is a separate number and can be the lower of the two at high ratios, so the specific model rating must be confirmed for the ratio you choose. Second, it takes no service factor. A 400W drive selected at exactly its calculated torque has no margin for shock, frequent starts or a jam, and should be multiplied up before the model is fixed.
The ratio arithmetic and the service factor logic are covered in more detail in service factor, backlash and lubrication in an electric motor gearbox.
A pallet conveyor with a chain drive needs 12 r/min at the head shaft and the load calculation gives 180 N·m running torque, with starts under load and a reversing cycle for two-way transfer.
Retrofits are where 400W causes the most trouble, because the mechanical and electrical infrastructure around the old drive was sized for a fraction of the load. Six items need re-verification.
The 400W unit is offered in both vertical and horizontal configurations, and this is not a cosmetic choice. The horizontal version has its output shaft parallel to the mounting surface and suits conventional conveyor and machine base layouts. The vertical version places the motor above or below the gearbox so the output faces down or up, which is the right answer when the driven shaft is vertical — a mixer, an agitator, a vertical screw or a rotary table — and the wrong answer when the machine only has a space problem, because a vertical unit raises the centre of gravity and puts the output seal at the bottom where any leakage is visible.
Choose the configuration from the direction of the driven shaft first, then check that the surrounding structure has room. If the driven shaft is horizontal and the constraint is side clearance, the right answer is usually a different gearbox arrangement rather than a vertical mounting.
400W and 750W are the two workhorses of the medium range, and the decision between them is usually about torque margin and shaft size rather than a step in power.
| Item | 400W | 750W (≈1 HP) |
|---|---|---|
| Trục ra | 22 mm | 28 mm |
| Supply | 3-phase 220 V / 380 V | 3-phase 220 V / 380 V |
| Mounting | Vertical or horizontal | Vertical or horizontal |
| Calculated torque at 30:1 | ≈ 73 N·m | ≈ 138 N·m |
| Cách sử dụng thông thường | Pallet and chain conveyors, packaging machines, small mixers | Heavy conveyors, agitators, pumps, lifting screws |
If your requirement sits within about 60% of the 400W capability at the ratio you need, 400W is the economical answer. If it sits at or above that, the 750W AC gear reducer motor gives double the torque and a larger shaft for the same electrical supply — and the 28 mm shaft is often the real reason to move up, because a 22 mm shaft carrying a heavy overhung sprocket at 400W torque is a bearing life problem waiting to happen.
Three situations call for a different answer rather than a bigger frame.
Include: required output speed in r/min; load torque, or the mass and radius being driven; duty cycle with starts per hour and reversing; available supply voltage and whether 220 V or 380 V three-phase; vertical or horizontal configuration and the direction of the driven shaft; shaft, keyway and flange requirements; ambient conditions and any washdown or dust exposure. Add the driven element type — conveyor, mixer, screw, rotary table — because it determines the service factor the sizing needs.
Cái 400W AC gear reducer motor page lists the standard 22 mm shaft, the 3-phase 220 V / 380 V options, both mounting configurations and the dimension drawing, so you can check the mechanical fit before requesting a ratio.
Three-phase only, available in 220 V or 380 V. There is no single-phase 400W model in this range; the largest single-phase option is 250W.
It depends entirely on the ratio. Calculated at 90% efficiency, a 400W input gives about 24.6 N·m at 10:1, 73 N·m at 30:1 and 245 N·m at 100:1. Confirm the gearbox’s own allowable load for the ratio you select, since it may be the lower figure.
A standard 22 mm output shaft. The 750W model in the same range uses 28 mm, and the small frames use 12–15 mm.
Yes, a vertical configuration is available alongside the horizontal one. Choose it when the driven shaft is vertical, and check that the oil level and seal position match the orientation.
Around 1.2 A full load at 380 V three-phase, and roughly double that at 220 V three-phase. Starting current on a direct-on-line start is typically four to seven times the full load figure, so size the contactor and overload accordingly.
Yes. A VFD gives controlled acceleration, reversing without a reversing starter, and speed adjustment, but the motor’s cooling falls with speed, so continuous operation well below nominal speed needs a torque and temperature check.
Treat 400W as an engineering change, not a power upgrade. It brings three-phase supply, a 22 mm shaft, a heavier housing and a starter that must be sized for real starting current. Calculate the output torque from your chosen ratio rather than from the power rating, apply a service factor for the actual load, and confirm the gearbox allowable load — then decide vertical or horizontal from the driven shaft direction. Get those four right and 400W is the most cost-effective drive in the medium range; skip one and the machine will be re-engineered around the motor.
