The Calculation Behind the Catalogue Number
A tubular motor is specified by the torque it can deliver at the curtain, not by the power it draws. Two motors with the same wattage can differ substantially in torque depending on the gearbox ratio, and that ratio is what determines whether the shutter runs or stalls. This is why the catalogue torque figure matters more than any other number on the spec sheet.
The Three Inputs That Decide the Motor
| Input | What to send | Why it changes the motor |
|---|---|---|
| Shutter area | Width × height in mm | Baseline curtain load |
| Tube diameter | 42 / 60 / 70 mm typical | Changes the mechanical advantage substantially |
| Fabric | Standard, laminated, blackout | Insulated fabric is heavier per square metre |
| Cycle frequency | Open-close cycles per day | Duty-cycle rating of the gearbox |
| Guide friction | Side guide condition | The most common cause of bottom-of-travel strain |
Torque Reference Table
| Torque class | Typical shutter size | Application |
|---|---|---|
| 10-15Nm | Up to roughly 2.0m wide | Standard domestic roller shutters, light fabric |
| 20-25Nm | Up to roughly 2.5-3.0m wide | Domestic shutters, laminated fabric |
| 30-40Nm | Up to roughly 3.5-4.0m wide | Larger shutters, heavy fabric, high wind exposure |
| 50-60Nm | Above 4m wide or industrial | Commercial and industrial applications |
The Correction Factors People Miss
- Drum diameter. A larger drum reduces the torque required at the curtain; a smaller one increases it. The same shutter on a 200mm and a 300mm drum does not need the same motor.
- Fabric weight. Laminated and blackout fabrics add mass per square metre that an area-only calculation misses.
- Side guides and tracks. Friction in the guides is the most common cause of a shutter that strains at the bottom of travel, and it is invisible in the motor specification.
- Cycle frequency. A motor specified for a domestic shutter is not automatically a motor for a shopfront opening twenty times a day.
A motor that is correctly sized for the shutter will reach the bottom of travel quietly. A motor that strains at the bottom of travel is usually not undersized on power — it is losing to guide friction, and a bigger motor will only mask that until the guides fail.
How to Buy This Without Guessing
- Send shutter width and height in millimetres, tube diameter, fabric type, and the number of open-close cycles per day.
- Receive a written motor recommendation with the torque figure stated, plus the control package list.
- Order one free sample per SKU ($30 DHL, buyer pays) and fit it to the least convenient shutter on your list before committing a batch.
Request a Quotation — Tubular Motor Sizing
Send the shutter width and height, tube diameter and the brand or model you need to replace. We reply with the exact motor size, EXW price, MOQ and lead time. MOQ 100 pcs per SKU.
Send Inquiry on WhatsAppEmail: Joanna@rfmando.com · MOQ 100 pcs per SKU · 1 free sample per SKU ($30 DHL, buyer pays) · Lead time 7-15 days · T/T 30/70 · EXW Xiamen
Request a Quotation — Tubular Motor Sizing
Send the shutter width and height, tube diameter and the brand or model you need to replace. We reply with the exact motor size, EXW price, MOQ and lead time. MOQ 100 pcs per SKU.
Send Inquiry on WhatsAppEmail: Joanna@rfmando.com · MOQ 100 pcs per SKU · 1 free sample per SKU ($30 DHL, buyer pays) · Lead time 7-15 days · T/T 30/70 · EXW Xiamen
Where to Order
- Somfy RTS Compatible Remotes — 5-channel and 16-channel LCD handsets
- Dooya Compatible Remotes — tubular motor controls and wall transmitters
- RF Remote Controls — full catalogue
Terms
MOQ 100 pcs per SKU. One free sample per SKU ($30 DHL, buyer pays). Lead time 7-15 days. Payment T/T 30/70. Prices EXW Xiamen. 100% functional test on every unit; a third-party QC report at AQL 5% is available on request.