The B&M Non-Rolling Brake
The B&M siren rotor/clutch assembly is designed to create the most sound with an efficient use of power and coasts very freely. Due to this efficient design it will tend to roll with the wind when the vehicle is moving at normal road speeds. This can cause a moderate 'growling' sound which can be annoying.
To resolve this situation B&M introduced the Non-Rolling Brake, which is standard on all of our sirens. It is spring-applied to keep the rotor from rolling when the siren is not in use. When the siren is to be used, the brake coil is energized which retracts the brake plunger so the siren will roll and coast freely. The brake coil is rated for continuous duty and draws about 1.25 amps. When the brake coil is de-energized, the spring applies the brake, stopping the siren from rolling and using no power.
You may have noticed that this is a different method of operation than most other sirens brakes. Those brakes are built like a doorbell; push the button and the brake is applied, stopping the siren. Releasing the button releases the brake. That design works on sirens with heavy, inefficient rotors and clutches. They do not tend to roll with the wind.
When installed according to the B&M Wiring Diagram, the Non-Rolling Brake achieves the following:
1. It keeps the siren from rolling when not in use.
2. A single Siren Enable switch can release the siren brake and enable the foot switches. This switch may be powered through the 'code 3' lighting control so that the siren cannot accidentally be used with the warning lights off.
Please keep in mind that B&M sirens with the Non-Rolling Brake are wired differently than most other sirens. If you have a unique installation that is not covered by the wiring diagram, or have any other questions, please contact us for assistance.
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