Hydraulic valve lifter

Hydraulic valve lifter

A device that eliminates the need for mechanical clearance in the valve train of internal combustion engines. Clearance is normally required to prevent the valve's being held open and destroyed as the valve train undergoes thermal expansion. However, clearance requires frequent adjustment and is responsible for much operating noise. The hydraulic lifter is a telescoping compression strut in the linkage between cam and valve, consisting of a piston and cylinder (see illustration). When no opening load exists, a weak spring moves the piston, extending the strut and eliminating any clearance. This action sucks oil into the cylinder past a check valve. The trapped oil transmits the valve-opening forces with little deflection. A slight leakage of oil during lift shortens the strut, assuring valve closure. The leakage oil is replaced as the spring again extends the strut at no load.

References in periodicals archive ?
In addition to combustion cylinder work, Tomadur also uses a Flex Hone tool to create a blended radius on hydraulic valve lifter bores, thereby avoiding scuffing problems on valve lifters.
Another business unit, hydraulic valve lifter manufacturer Precision Engine Products Corp.
Hydraulic Valve Lifters Requiring No Maintenance Service Adjustments
Service Bulletin SB-97-6A, issued in 1997, calls for removing and discarding hydraulic valve lifters.
These include an aluminum block with cast-iron cylinder liners for extended service life; maintenance-free hydraulic valve lifters designed to ensure full power over the life of the engine; larger sleeve bearings on both the flywheel and PTO side designed to accommodate heavy loads; a heavy-duty air cleaner with integrated rain cap; and an integrated oil cooler mounted under the cylinder access cover, designed to provide improved cooling while still maintaining a compact profile.
Another Eaton specialty is engine valves, hydraulic valve lifters and cylinders, as well as a diverse variety of switches and other controls, which the company manufactures for more than 70 passenger car and truck manufacturers.
We also included items like a nylon cam gear, hydraulic valve lifters that reduce the clanging of valves.
Other features of the powertrain include hydraulic valve lifters, a Bosch alternator and electronic fuel injection speed governing.
The engine has hydraulic valve lifters, Cull pressure lubrication with oil cooler and a Nelson heavy-duty air cleaner.
The new joint venture will manufacture and sell automotive and motorcycle engine valves and hydraulic valve lifters for the Chinese market.