This page describes the simple process of the loco running around a train, as would occur at most branch line termini, and also main line stations such as Manchester Piccadilly.

 

Step 1 - The train approaches the platform, slowing to a stop

Step 2 - The train stops in between the two loops, allowing room for the loco to run around 

Step 3 - The loco runs around the train via the other side of the loop

Step 4 - The train is ready to depart again in the opposite direction