By the SightShield team · · 3 min read
Why sizing matters
An undersized gate motor works — for a while. Then it overheats on busy days, the gears wear, and the gate starts stopping halfway. Indian gates are often made of heavy mild steel, sometimes heavier than the owner realises, and many are motorised years after being built. Getting the weight, length and usage right is the single biggest factor in how long a gate automation lasts.
Weight classes for sliding motors
Manufacturers rate sliding motors by the maximum gate weight. Examples from published datasheets:
| Class | Typical rating | Examples from datasheets |
|---|---|---|
| Residential | 400–500 kg | Nice RB400 (400 kg), FAAC 740 (500 kg) |
| Medium | 600–900 kg | Nice RB600 / new Robus (600–800 kg), FAAC 741 (900 kg) |
| Heavy | 1,000 kg and above | Nice RB1000 (1,000 kg), FAAC 844 (around 1,600–2,200 kg depending on version) |
| Industrial | Several tonnes | Specialist heavy-duty operators |
Length matters too
Longer gates put more load on the motor and catch more wind. Manufacturers often reduce the allowed number of cycles for longer gates — for example, Nice quotes 40 cycles per hour for a 4 m leaf and 20 cycles per hour for an 8 m leaf on its RB600 and RB1000 motors. Swing gates are even more sensitive to leaf length and wind.
Duty cycle: how often the gate runs
Duty cycle tells you how hard a motor can work without overheating. It is expressed either as a percentage or in cycles per hour, and the two are not directly comparable. FAAC, for instance, lists its 740, 741 and 844 sliding motors at 30%, 40% and 70% respectively, while boom barriers such as FAAC’s B680H are rated for continuous use.
| Site | Typical use | What to look for |
|---|---|---|
| Villa or house | A few to a few dozen cycles a day | Residential motor with headroom |
| Small office or shop | Moderate | Medium-duty motor |
| Apartment complex | Hundreds of cycles a day | High-duty sliding motor or continuous-use barrier |
| Factory gate | Frequent, heavy gate | Heavy-duty or industrial operator |
Rule of thumb
- Weigh or calculate the gate weight — do not guess.
- Choose a motor rated well above that weight.
- Check the length limit for that motor.
- Match the duty cycle to your busiest hour, not an average day.
- Fix the gate first: a stiff gate on a bent track will defeat any motor.
Rack and pinion
Sliding motors drive the gate through a toothed rack fixed along the gate and a pinion gear on the motor. The rack must be fixed straight and at a consistent height, with a small gap to the pinion so the gate’s weight does not rest on the motor. Poorly fitted racks are a common cause of noise and premature wear.
Gate automation installation →Signs a motor is undersized
If you see these, fix the gate’s movement first; if it still struggles, the motor is too small for the gate or the usage.
- The motor gets very hot after a few cycles.
- The gate slows down or stops partway, especially in the afternoon heat.
- The force setting has been turned up to the maximum to make it move.
- Thermal cut-outs trip during busy periods.
- Pinion teeth or rack wear quickly.
Quick answers
How do I know my gate’s weight?+
Calculate it from the steel sections and dimensions, or have the installer estimate it on site. Many Indian mild-steel gates are heavier than expected.
What is duty cycle in a gate motor?+
A measure of how much the motor can run without overheating, given as a percentage or cycles per hour. Busy gates need higher duty cycles.
Can I use a residential motor for an apartment gate?+
Usually not. Apartment gates run far more often and need a high-duty or continuous-use operator.
Does a heavier gate always need a three-phase motor?+
No. Many heavy-duty single-phase operators handle large gates; three-phase motors are used for the heaviest and busiest industrial gates.
Can wind affect a sliding gate motor?+
Less than a swing gate, but tall solid sliding gates still face wind load and need adequate guides and motor margin.