System Examination: Safe Braking

Mechanical brakes must be used if the output shafts on motors or gearboxes are affected by forces that would trigger movement when the motor was shut down. Example applications are vertical axes or motors with high inertia. The operation of vertical axes is a special case as far as safety technology is concerned. The failsafe principle – the removal of power to the drives in the event of an error – is generally applied in safety technology, but in this case it would not lead to a safe condition because falling loads present a hazard. Mechanical brakes are incorporated to rectify this; their functionality must be constantly verified using special proof tests. As with
the encoder systems, various versions are available to fit the specific safety requirements. Dual channel  capability can be implemented either through two independent brakes or through a brake with two separate brake circuits. The advantage of two separate brakes is that faults can be covered within the mechanical transmission elements between the drive and the process. The brake configuration depends largely on the machine design and the overall safety concept.