Compound lever sudden movement of the key. The earliest remaining writings regarding levers date from the 3rd century BC and were provided by Archimedes. ""Give me a place to stand, and I shall move the earth with a lever"" is a remark attributed to Archimedes, who formally stated the correct mathematical principle of levers (quoted by Pappus of Alexandria). The idea of the compound lever is attributed to the Birmingham inventor John Wyatt in 1743, when he designed a weighing machine that used four compound levers to transfer a load from a weighing platform to a central lever from which the weight
Lever frame as it requires more force to move the lever. Therefore, later, especially in Germany, lever frames with pivots inside the signaller's room were used, that allow for a lever angle of approximately 180° (as seen on the photo on the right). By the movement of individual levers (or sometimes cranks), signals, points, track locks, level crossing gates or barriers and sometimes movable bridges over waterways are operated via wires and rods. The signaller chooses the correct combination of points, facing point locks and signals to operate, which will control the movement of each train through their area of control. The