Compound lever the force of pushing back the stick to the levers and they rub against the wheels, using friction to slow and eventually stop the train. These are everyday applications of this mechanism. A piano key is a compound lever of the first-class, since the fulcrum is between the weight to be moved and the power. The purpose of this lever is to translate a small movement (depression of the key) into a larger and fast movement of the hammer on the strings. The quality of the resulting tone depends on whether the final speed is brought about by gradual or
Lever frame required to move them. Mechanical lever frames and interlocking have now largely been replaced by modern, much larger electrical or electronic route interlockings located in Power Signal Boxes and more recently Integrated Electronic Control Centres which are able to control much larger areas of the rail network. A mechanical lever frame is designed to harness mechanical advantage to operate switch points, signals or both under the protection of the interlocking logic. The levers are connected to field appliances via solid pipes or taut wires such that the full travel of the lever will reliably cause full travel in the appliance.