Steam brake

A vapor barrier is a type of brake for steam locomotives and their Tender, in which a steam cylinder acts directly on the brake rod.

Steam brakes came mainly in railways used, who used the vacuum brake as a brake on the wagon train and the steam engine did not own Saugluftbremszylinder, such as in Britain, or only one force acting on the trainset cable brake (eg Heberleinbremse ), used, for example in Saxony at the narrow gauge railways.

Vapor retarders are now only found in selected museum vehicles.

Operation

About one in stages or continuously variable valve ( brake valve ) in the cab of the locomotive steam is supplied from the locomotive boilers the steam brake cylinder. By injected steam, the piston is set in the steam cylinder in motion, the piston rod transmits the braking force on a respective rod on the brake pads of the vehicle, whereby the braking effect is achieved. By a return spring, the piston is returned to the idle state when the steam supply is interrupted. And condensing the expanded vapor is passed through a drainage valve of the steam cylinder.

The steam brake acts directly and immediately. Due to sudden opening of the brake valve can be easily over-braking with blocking of the wheels. Pressing the vapor barrier, therefore, required a lot of experience of the engineer's.

The vapor barrier can both directly via a lever (valve) as well as indirectly be operated together with the vacuum brake. In the latter case, an affiliate of the suction air control valve regulates the steam supply to the brake cylinder, so that the vapor barrier even during emergency braking or Zugtrennungen can be automatically effective ( so-called automatic steam brake).