Pulley system, the massless and frictionless pulleys do not dissipate energy and allow for a change of direction of a rope that does not stretch or wear. In this case, a force balance on a free body that includes the load, "W", and "n" supporting sections of a rope with tension "T", yields: The ratio of the load to the input tension force is the mechanical advantage "MA" of the pulley system, Thus, the mechanical advantage of the system is equal to the number of sections of rope supporting the load. A belt and pulley system is characterised by two or
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