Slam-door train

A slam-door train or slammer is a set of railway coaches, a diesel multiple unit (DMU) or electric multiple unit (EMU) that were designed before the introduction of automatic doors on railway carriages in the United Kingdom and other countries, which feature manually operated doors. The name is due to of the characteristic 'slam' noise made by the doors when closed quickly.

Some slam-door train designs featured doors that could only be opened from the outside, so passengers had to lean out of the window to reach the outside door handle. Slam-door trains often had many more doors than newer trains; some designs featured a door for every individual seating bay; some units had individual compartment doors.

The term "slam-door train" is more commonly applied to Mark 1 and Mark 2 DMUs and EMUs, though may refer to locomotive-hauled trains featuring the same door design.