How to Specify the Right Motor for Your Installation

Ellard
Aug 29
2 min read

When it comes to roller shutters, roller garage doors, roll-up high-speed doors, or fire shutters, getting the motor specification right is critical for performance, safety, and reliability.

At Ellard, we follow a proven process to size every motor correctly, and now you can use the very same method to spec your own installations.

This guide walks you through the exact details we ask for and why they matter:

1. Door Width and Height

We start with the clear opening width and the height to the barrel centreline.

This gives us the overall size and weight distribution of the door.
Even a small height difference can change the motor requirement.

2. Curtain / Lath Type and Weight

Next, we require Curtain/ lath type and weight. Not all curtains weigh the same — and it is one of the biggest factors in choosing a motor.

We have guide weights for the most common lath types.
If you’re using something different, provide the exact weight so we can calculate accurately.

3. Bottom Rail Type

Bottom rails add weight and affect balance.

Ellard has guide weights for standard rail types.
For non-standard rails, we may ask for confirmation to avoid under- or over-specifying the motor.

4. Additional Barrel Wraps

If the curtain doesn’t close flush and instead requires extra wraps around the barrel, this needs to be factored into the calculation.

More wraps = more torque required from the motor.

5. Reduction Ratio (if geared installation)

For geared installations not supplied directly by Ellard, we need the reduction ratio you’re using. This ensures our motor sizing matches your setup.

Why This Matters

Getting these details right means:

Correct motor sizing (no under- or over-specifying)
Longer lifespan for motors and doors
Safer and more efficient operation

The details you provide feed directly into our door specification calculator, allowing us to present the best motor options for your application.

At this stage, we can also recommend the correct barrel size, coil diameter, and the ideal opening and closing speeds, all tailored to the motor type you select.

This step-by-step approach is the exact same process our team follows when you bring us a project. By using it, you’ll have confidence that every installation is specified correctly.

To support you further, we provide on-site training that covers the full process of working with Ellard’s motors, not just when you’re installing, but through every step leading up to it. With this knowledge, you’ll understand the same process our team follows to spec each project with precision.

Ready to spec a motor? Use this guide to collect your measurements and project details, then send them to our team at sales@ellard.co.uk. We’ll confirm the motor and make sure you have everything you need.