Countersteam brake

When comparing vapor barrier is the exploitation of the working principle of the steam cylinder with rotary valves on a steam locomotive, to change the working direction by changing the design sense of control and thus of the leader of the slide opposite the steam piston. Due to the inertia of the steam locomotive in the existing direction of movement changed the working direction of the steam cylinder, contrary to previous work direction initially causes the deceleration of the movement of the piston rod and the power transmission to the engine of the locomotive to a stop.

The other vapor barrier works with steam, it is often confused with the counter- pressure brake that but works with ambient air and a steady brake ( dynamic brake) is used, and is approved as a separate braking system.

Principle of operation

When comparing vapor barrier is in the proper sense is not a brake, but only to the braking effect achieved utilizing the principle of operation of a steam engine. It is thus not a separate component of a steam locomotive.

However, the principle against vapor barrier can be achieved only for rotary or piston valves. For simple flat valves, due to their construction principle no offsetting of steam is possible, since the slider is pushed only by the applied steam pressure at opposite actuation of the slider using steam this would immediately lifted from the slide glass, and the escape of steam has no effect on the piston.

Experienced steam engine driver can use the counter vapor barrier be reversed from a direction of movement in the opposite direction of the steam locomotive with virtually no discernible stop, since the actual " switching over " takes place already in the original direction of motion. However, this procedure assumes precise knowledge and experience, as in incorrect handling even damage to the engine of the locomotive are possible.

With steam locomotives without second independent braking system (such as air brakes, vacuum brake, vapor barrier ) for the Driver in addition to the generally always present throw lever or parking brake, the counter vapor barrier was applied as a second braking system. Today, existing steam locomotives have usually for approval purposes two separate braking systems, so that the counter vapor barrier is not considered a brake system, but certainly applies.

Swell

• Heym, Rudolf: How do they actually work, the steam engine, Bruckmann, 2004, ISBN 3765472557?

• Steam machine technology
• Steam locomotive technology
• A rail vehicle brake