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
Lifting bag a hazardous operation with high risk of entanglement in an uncontrolled lift or sinking. If a single bag is insufficient, multiple bags may be used, and should be distributed to suit the load. There are also lifting bags used on land as short lift jacks for lifting cars or heavy loads or lifting bags which are used in machines as a type of pneumatic actuator which provides load over a large area. These lifting bags of the AS/CR type are for example used in the brake mechanism of rollercoasters. The volume of the bag determines its lifting capacity: each litre