Ventilstödrum

Ventilstödrum is a Swedish technical term referring to a cylindrical component that provides support for a valve within a valve train. The part serves to align and support the valve stem and to transmit the forces generated by the cam, actuator, or rocker to the valve. By offering a stable bearing surface, the ventilstödrum helps control valve motion, reduces bending moments on the stem, and contributes to maintaining proper valve timing and sealing. Some designs include lubrication channels or bushings to minimize wear.

In construction, a ventilstödrum is typically a precisely machined cylinder located in the valve guide assembly or directly at the valve stem. Materials vary by application and may include bronze or brass for good sliding properties, or steel for strength and heat resistance. The diameter, length, and bore tolerances are specified to ensure minimal play and reliable operation, especially at high operating temperatures.

Applications are largely in specialised or older machinery and in some Swedish or European equipment, such as certain reciprocating engines, steam engines, and process valves. The term is not universally used in modern technical literature and may be replaced by more general terms like valve guide or valve stem bearing in other languages.

Maintenance involves inspecting for wear, scoring, or play in the valve stem and replacing the ventilstödrum if clearances exceed specification; regular lubrication or oiling is often required in metal-on-metal designs.