Page "Railway air brake" Paragraph 45

The main competitor to the air brake is the vacuum brake, which operates on negative pressure.

The vacuum brake is a little simpler than the air brake, with an ejector with no moving parts on steam engines or a mechanical or electrical " exhauster " on a diesel or electric locomotive replacing the air compressor.

Disconnection taps at the ends of cars are not required as the loose hoses are sucked onto a mounting block.