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.
Delphi developed the first direct hydraulic valve lifter, and also led the automotive industry in incorporating the first roller hydraulic valve lifter into production vehicles.
The company was the first to develop a direct-acting hydraulic valve lifter, and to incorporate the first roller hydraulic valve lifter into production vehicles.
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.
Growth in the worldwide market for diesel engines, as well as the development of gasoline engines requiring more hydraulic valve lifters, creates solid internal growth prospects for Stanadyne.
5 million hydraulic valve lifters shipped to Toyota in Japan during the last 18 months included no defective parts; that the plant has reduced its overall defect rate for all customers in North and South America, Europe, and Asia to two parts per million; and that the plant was the first GM plant in the U.
The new joint venture will manufacture and sell automotive and motorcycle engine valves and hydraulic valve lifters for the Chinese market.
The award for 1994 quality performance was earned by Delphi's Grand Rapids, Michigan plant, which makes hydraulic valve lifters for shipment to Toyota for vehicles made and sold in Japan.
The award was earned by AC Delco Systems' Grand Rapids, Michigan plant, which makes hydraulic valve lifters for shipment to Toyota for vehicles made and sold in Japan.
The award was given for high quality reached in hydraulic valve lifters made in AC Rochester's Grand Rapids, Mich.
Saab convertibles derive their power from 16-valve, four-cylinder engines with double overhead camshafts and maintenance-free hydraulic valve lifters.