Spring applied brakes from INTORQ, from 0.1 to 2400Nm, are available in the UK from Techdrives.
The company’s brakes are used in wind turbine installations, in particular where normally-on spring applied holding brakes are needed. On blade pitch drives, for example, where servo motors continually adjust the blade angle to maintain the running speed, the brakes hold the blades in a fixed position during periods of shutdown. Secondly, brakes are needed on the azimuth drives which rotate the nacelle into wind – here, they hold the position except when adjustment is needed.
In such applications, the brakes need to withstand extremes of temperature and damp conditions with minimal maintenance. INTORQ BFK series brakes are used by several wind turbine manufacturers with torques from 14 to 200Nm. These are often customised but are always single disc design with multiple engagement springs and DC coil release. They are mounted onto the back of the motors; servo motors for the pitch drives and standard asynchronous motors for the azimuth drives, of which there are typically four or five on a wind turbine. They are designed for 100% running time with coil engaged and the rated torque can be applied with either dynamic or static brake engagement.
Modifications can be provided, such as a ‘cold climate’ version which allows operation with ambient temperatures from -20°C to +40°C. INTORQ also provides a plastic coating to the splines of the brake disc which reduces backlash to almost zero. To ensure reliable brake release, even with large air gaps, a specially developed brake rectifier is used which gives a temporary over-excitation of the brake coil.