Puretic power block Puretic power block The Puretic power block is a special kind of mechanised winch used to haul nets on fishing vessels. The power block is a large powered aluminium pulley with a hard rubber-coated sheave. While many men were needed for the back-breaking work of hauling a purse seine manually, the same work could be done by fewer men with a power block. The Puretic power block revolutionized the technology of hauling fishing nets, particularly purse seine nets. According to the Food and Agriculture Organization of the United Nations (FAO), "no single invention has contributed more to the success of
Electro-pneumatic brake system on British railway trains thereby activating the disc brake. The "presence" of the voltage holds the brakes "off", providing a Fail Safe system. The 3 step "Westcode" brake uses three wires and these operate in a binary sequence to control the brake step. 10 & 11 are the brake coding to provide the 3 steps, 12 wire is emergency brake, 15 wire is EP brake negative. Positions on the brake handle are: This system remains in use today. On the previous EP brake systems, if the train divided or a serious air leak occurred the drop in Brake Pipe pressure automatically caused the brakes