Behind the box of a shop's metal shutter hides a precise mechanical assembly: the motorised axle. Understanding its components helps you talk with your technician — and grasp why some faults require complete removal.
The components of a central-motor axle
- The winding tube: a steel axle (often 133 or 168 mm in diameter) onto which the curtain rolls
- The central motor: fixed mid-tube, driving it through a toothed ring; its electro-brake holds the shutter at rest
- The compensation springs: coiled around the tube, they balance the curtain's weight to relieve the motor
- The bearings and end plates: they carry the rotating axle at both ends
- The safety fall arrester: mandatory, it instantly locks the axle on overspeed (spring or brake failure)
- The emergency operation: crank or winch to open during a power cut
How the assembly cooperates
On the way up, motor and springs combine their efforts: a well-compensated 300 kg curtain asks the motor for only a fraction of that weight. On the way down, the springs brake the fall and "recharge". This balance explains the golden rule: any spring or motor replacement requires recalculating the compensation.
Signs of a tired axle
Laboured rising, banging in the box, a shutter that creeps down a few centimetres on its own: slack springs or a worn brake. Never open a box yourself — springs under tension are dangerous. Our technicians service and replace axles, springs and central motors throughout Île-de-France.