Dynamic Load Analysis: Why Your Curtain Motor's Torque Rating Isn't Everything

A high-torque motor can still fail. We explain the difference between static and dynamic friction, breakaway torque, and why system inertia is a critical factor in motor selection.

: curtain motor torque, breakaway torque, dynamic load calculation

Selecting a motor based solely on its maximum torque rating is an oversimplification. A system must be engineered to overcome the specific forces encountered during operation, which are not constant.

1. Breakaway Torque (Static Friction):
This is the torque required to initiate movement from a standstill. Static friction is always higher than kinetic (moving) friction. The motor must deliver a peak torque exceeding the breakaway torque of the entire system, which is influenced by track alignment, weight on the gliders, and the initial "stickiness" of the curtains.

2. Kinetic Torque (Dynamic Friction):
Once moving, the torque required to maintain motion is lower. This is the continuous torque the motor must provide.

3. Inertial Load:
Torque is also required to accelerate the mass of the curtains and gliders (T = Iα, Torque = Moment of Inertia x Angular Acceleration). A system with heavy curtains and a long track has significant inertia. A motor must have enough torque not just to move it, but to start and stop it smoothly within a desired time. An undersized motor will struggle, overheat, or fail to achieve the programmed speed.

The Engineering Process:
A properly sized motor is selected by calculating:

• Peak Torque Demand: (Breakaway Torque + Torque for Initial Acceleration).

• Continuous Torque Demand: (Kinetic Friction Torque + Torque for Maintaining Speed).

The motor's torque-speed curve must show that it can deliver the required peak torque without stalling and the continuous torque without overheating.

Avoid motor failure and poor performance. Our technical team performs dynamic load calculations based on your specific track length, curtain weight, and desired open/close time. Submit your project parameters for a guaranteed motor recommendation.