Lever frame

Mechanical railway signalling installations rely on lever frames for their operation to interlock the signals, track locks and points to allow the safe operation of trains in the area the signals control. Usually located in the signal box, the levers are operated either by the signalman or the pointsman.

The world's largest lever frame is believed to have been in the Spencer Street No.1 signal box in Melbourne, Australia, which had 191 levers, but was decommissioned in 2008. The largest, currently operational, lever frame is located at Severn Bridge Junction in Shrewsbury, England, and has 180 levers; although most of them have now been taken out of use.