A brake motor is a standard electric motor with a built-in electromagnetic brake at the rear (non-drive) end of the shaft. The brake operates on the fail-safe principle: when power is cut or deliberately switched off, the brake engages automatically. This makes brake motors essential in any application where a load must not run away or overshoot.
How does an electromagnetic brake work?
The brake consists of three main components: a spring pack, an electromagnet (coil) and a brake disc coupled to the shaft. The operating principle:
- Motor on: the coil is energised, the magnet attracts the armature plate, the spring pack is compressed and the brake disc rotates freely. The shaft can turn.
- Motor off or power failure: the coil loses voltage, the spring pushes the armature plate against the brake disc and locks the shaft within milliseconds.
Braking time (from full load to standstill) is typically 0.05 to 0.3 seconds, depending on braking torque and the inertia of the driven load.
Van Bodegraven stocks IP67 brake motors as standard in Dordrecht. IP67 means fully dustproof and submersion-resistant to 1 metre for 30 minutes, suitable for washdown environments, offshore applications, the food industry and outdoor installations without additional enclosures.
AC brake versus DC brake
| Feature | AC brake | DC brake |
|---|---|---|
| Supply | Direct from mains (230 V or 400 V AC) | Rectified voltage, built-in rectifier |
| Response time | Slightly slower (mains frequency dependent) | Fast (<50 ms when properly tuned) |
| Wear | Lower at low switching frequency | Lower at high switching frequency |
| Application | Hoists, goods lifts, standard industry | Cranes, chain hoists, high-cycle applications |
| Price | Lower (simpler construction) | Slightly higher due to rectifier unit |
Applications: when is a brake motor required?
- Hoists and chain hoists: legally required in class-certified installations. The brake holds the load during power failure or emergency stop without a mechanical wheel brake.
- Goods lifts and passenger lifts: dual brake configuration for primary and secondary safety conforming to EN 81.
- Inclined conveyors: prevents reverse rolling of the belt on shutdown or fault.
- Positioning drives: stops exactly on position without coasting. Essential in CNC machining, packaging lines and assembly tables.
- Doors and roller shutters: the brake holds the door open or closed during power failure.
- Woodworking machines: immediate stop on releasing the control button or emergency stop activation drastically reduces run-on risk.
Calculating braking torque
The required braking torque T_brake (Nm) depends on the mass to be stopped, the speed and the desired stopping time. As a rule of thumb:
- Static load (hoisting): T_brake ≥ 1.5 × the drive torque at rated load. The safety factor of 1.5 is standard in the relevant norms.
- Dynamic load (conveyor): T_brake = (J × Δω) / t_brake, where J is the total inertia (kg·m²), Δω the angular velocity change (rad/s) and t_brake the desired braking time (s).
- Inclined conveyors: add the gradient force to the static component.
IP class and environmental protection
| IP class | Protection | Typical application | Stock |
|---|---|---|---|
| IP55 | Dust-protected + splash-proof | Standard industry, indoor | ✓ Ex stock |
| IP65 | Fully dustproof + jet-water resistant | Washplaces, outdoors with shelter | ✓ Ex stock |
| IP67 | Fully dustproof + submersion 1 m / 30 min | Washdown, offshore, food industry | ✓ Standard stock |
| IP69K | High-pressure cleaning up to 80°C | Abattoirs, dairy, pharmaceutical | On request |
Standard versions and options
- Manual brake release: allows manual release of the brake to rotate the shaft by hand during commissioning or maintenance without powering the motor.
- Adjustable braking torque: some versions allow adjustment via spring settings without disassembly.
- Wear indicator: visual or electrical signal when the brake lining needs replacement.
- Thermal protection (PTC/PT100): monitoring of winding temperature for thermal protection.
- Encoder version: for position feedback in combination with a frequency drive or servo drive.
Delivery and stock at Van Bodegraven
Van Bodegraven supplies brake motors in IEC frames 63 to 280, power 0.12 kW to 75 kW, in both AC and DC brake configurations. Popular configurations are held in stock in Dordrecht with a 1-2 working day lead time. Specific voltage, higher IP class, double brake or non-standard frame are built to order (3-5 weeks). Emergency delivery for production downtime is always negotiable.
No rights can be derived from the information in this article. Contact us for a concrete quote and current delivery status.
Need a brake motor for your application?
Send us your power rating, speed, brake type and IP class. We respond within one working day. IP67 versions are standard stock in Dordrecht.