The small four lever frame I used during development of my mechanical signalling and point operating systems is a rather nice `GEM' lever frame kit, the leverframe is constructed from whitemetal castings, one for each end, one inner section for each lever and a long threaded bar which passes through each section of frame and the individual brass levers providing them with a pivot point, the bar is fixed with a nut at each outer end which holds the whole frame together. This frame is now spare as Stoneybridge West is now controlled with brass pushrods from the rear of the layout which operate mechanical linkages to points, signals and other equipment.

A mechanical lever frame can be quite easily electro-mechanically locked during train movements to ensure that movements conflicting the current train path cannot be made until the train has left the section. The train passes over sensors below the track as it exits the section and a short pulse of power is sent to the solenoid unit moving the lock bar below the arc of the lever tails enabling them to be moved freely. For failsafe operation the traction current to the section could also be isolated whilst the lever lock is Off. This would guard against a train entering the controlled section until its path is correctly set and the lever frame locked. By locking the frame the appropriate signal can then be cleared and traction current is reconnected to the running rails, the train can then safely enter the section, the driver/operator knowing there is a clear path set through the section ahead as far as the Home signal. The Home signal should only be cleared if the points ahead of it are set correctly and the levers are locked. The lever frame is automatically unlocked when the train has left the section and passed a set clearing point located in the next block section ensuring the train is clear of the points and signals in the controlled section operated from the lever frame.