Hydraulic valve, especially for automatic gearing of vehicle, has piston made of abrasion-resistant plastics with injected metal or ceramic insert part at surface contacting valve casing

摘要

The valve has a piston sliding in a valve casing. The piston is made of abrasion-resistant plastics and has an injected metal or ceramic insert part. The insert part is concentrated at the upper surface of the running surface contacting the valve casing. The piston preferably has a metal core (4). The outer wall of the piston may be coated with a metal or ceramic layer.