Vertical movement of loads introduces varying requirements for brake safety and integrity. Specialist manufacturer INTORQ has a range of answers with their spring-applied brake systems in disc and calliper designs. Brakes are capable of both emergency stop and holding duties. Basic brake designs are highly reliable with multiple springs and stable friction material. Where vertical movement of goods or people requires higher integrity, INTORQ has three concepts for increased safety.
A simple option is to duplicate the braking with a double brake, effectively two brakes piggy-backed together into one assembly. These are available starting at 2 × 4Nm and extending to 2 × 1800Nm. Both brakes are normally used together, so in the event of an unlikely catastrophic failure to one of them, 50 per cent of the torque remains. Microswitches can be fitted to monitor correct brake operation and therefore to signal a fault.
The next option is to supply a single brake that is modified with two internal circuits. The modifications are made to both the mechanical structure and the electrical circuit. Torques range from 15–900Nm and the BFK454 brake range meets the requirements of TRA 200 and EN-81 for hoists. Such dual circuit brakes with their redundant braking feature are also used in personnel lifts.
Caliper brakes are also a useful option where redundant braking is required. For example, if four calipers are enough to generate the emergency torque required, the addition of just one more can give safe operation should a caliper fail. Microswitch monitoring will detect the failure and shut down operation. INTORQ offers caliper brakes suiting discs of diameter 20–500mm with thrusts from 1200–8000N. Over-excitation of the DC brake coils is used for reliable release with large running air gaps.
INTORQ products for lifts, hoists and cranes are adaptable to meet the safety needs of individual applications. The full range of spring-applied brakes covers torques from 0.1–2400Nm and is available in the UK through Techdrives. For more information, visit the website at www.techdrives.co.uk.