Hikiventtiilit

Kun höyryä ei enää päästetä sylintereihin, ne jäähtyvät nopeasti. Sylintereihin jäävä höyry tiivistyy siten takaisin vedeksi melko nopeasti. Koska vesi ei ole kokoonpuristuvaa ja jos sitä kertyy riittävästi sylintereihin, se voi aiheuttaa katastrofaalisen voimansiirtovian joutuessaan männän ja sylinterin seinän väliin.

For this reason there are cylinder cocks. They are operated by a valve from inside the cab, allowing water to be released from the cylinders. As some of the steam from the cylinder is lost while the cylinder cocks are open, acceleration is reduced. Typically, the drivers open cylinder cocks for a few seconds after being stationary for some time.

Cylinders can also fill with water in a process called priming. This is the case of the boiler having too much water, or running the vehicle with the cutoff set in the opposite direction, causing water to overflow into the cylinders.

See also: Mechanical Powertrain Damage, Water Level, Cutoff