Top and tail

A top-and-tail railway train has locomotives at both ends, for ease of changing direction. This is a British term. It is normal for only the leading locomotive to power the train when in top-and-tail mode, cf push pull operation with both locomotives powering.

It is properly distinct from a push-pull train, which has a locomotive at one end and a control cab at the other end.

Trains going up zig zags of the Khyber Pass are top-and-tailed, although Pakistan Railways calls this by a different term.

In Japan, the term "push-pull" is confusingly used to describe trains top-and-tailed with a locomotive at either end. (True push-pull operation with a locomotive at one end is not seen on Japanese mainline railways.)

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Wikipedia