ventildåser

Ventildåser are components used in the valve train of internal combustion engines and other valve-operated systems. The term combines venti- (valve) with dåser (casing or sleeve), referring to the cylindrical body that houses the mechanism responsible for opening and closing a valve.

Function and construction

A ventildåser typically consists of an outer housing, a sliding plunger or tappet, seals, and often a spring or hydraulic chamber. In hydraulic versions, oil under pressure within the chamber takes up lash and provides damping, reducing wear and combustion noise. In mechanical variants, a direct interface between cam and valve stem relies on precise clearances to control motion. The design transfers the camshaft’s rotary motion into the translational movement of the valve, while often maintaining a controlled valve clearance.

Operation and variants

As a cam lobe pushes the ventildåser, the valve stem is moved to open the valve. Hydraulic lash-adjusting ventildåser automatically compensate for wear by adjusting the effective clearance, while non-hydraulic versions depend on preset tolerances. Variants can differ in size, material (typically steel alloys), and whether they function primarily as dampers, lash adjusters, or both within the valve train.

Applications

Ventildåser are common in many engines using overhead or side-valve configurations, including automobiles, motorcycles, and some aviation and industrial engines. They may be integrated into the cylinder head as part of the valve train assembly or mounted as modular units.

Maintenance and failure

Signs of wear or failure include abnormal ticking or tapping sounds, loss of valve seal, reduced compression, or erratic engine timing. Maintenance involves inspecting for excessive play, wear on the plunger or seals, and ensuring proper lubrication in hydraulic versions. Worn ventildåser are typically replaced as a unit to restore correct valve timing and performance.

See also

Valve train, hydraulic lifter, tappet, camshaft.