... You have the diagram unusually arranged with the inner slip switches lying normal across the diamond: 2_291800_040000000.png It is more usually arranged like this: 2_291801_020000000.png Pulling lever 3 provides a crossover between the Up and Down Mains. Then also pulling lever 2 connects the Up Main to the Down Loop instead of the Down Main. Or also pulling lever 1 connects the Down Main to Up Loop instead of the Up Main. Pulling levers 1 and 2 instead of 3 provides a crossover between the two Loop lines. Here's a more conventional view: 2_300731_570000000.png Slip switches 1 and 2 lie normal for the slip road, so that pulling only 3 provides a main line crossover. However, I see from your RMweb topic that you are modelling GWR practice, in which case things may be done differently. We need a reply from Howard (JFS) who is the signalling expert in these parts. It's important that the levers are arranged in the frame so that it is never necessary to pull a lever between two which are already pulled. cheers, Martin. posted: 30 ...