Seals for Hydraulic Assemblies

Abstract

A sealing device for a hydraulic assembly wherein hydraulic fluid is contained in working chamber ( 53 ) formed between body ( 52 ) and thrust member ( 51 ) of the assembly. The device comprises annular seal ( 63 ) with opposed sealing faces which are urged into sealing engagement between body ( 52 ) and thrust member ( 51 ) which have convergent sealing faces. The device may also have a pressure relief valve ( 100 ) tapped into the over-stroke end of chamber ( 53 ) to protect seal ( 63 ) from over-stroke damage comprising porous body ( 101 ) which allows fluid to bleed from chamber ( 53 ) and allows seal ( 63 ) to pass the tapping point without obstruction.

1 . A sealing device for an hydraulic assembly wherein hydraulic fluid is contained in a working chamber formed between the body and the thrust member of the assembly comprising an annular seal with opposed sealing faces which are urged into sealing engagement between the body and the thrust member which have convergent sealing faces. 
     
     
         2 . The sealing device of  claim 1  which also comprises an annular mating spring clip retained in the body or in the thrust member of the assembly which bears against a non-sealing face of the annular seal to ensure primary sealing engagement between the body and the thrust member. 
     
     
         3 . The sealing device of  claim 1  in which the annular seal is formed with a pair of annular sealing lips which are urged into sealing engagement between the body and the thrust member of the assembly at an initial low pressure, the remainder of the seal being urged into sealing engagement at higher pressures. 
     
     
         4 . The sealing device of  claim 1  in which the seal is spring loaded when it is placed in position so that it attempts to returns to its original shape thus urging sealing engagement between the body and the thrust member. 
     
     
         5 . The sealing device of  claim 1  in which the seal has a rounded heal which rolls under pressure to maintain sealing engagement. 
     
     
         6 . The sealing device of  claim 1  which is provided with a pressure relief valve tapped into the over-stroke end of the chamber to protect the annular seal from over-stroke damage comprising a porous body which allows hydraulic fluid to bleed from the chamber and which allows the annular seal to pass the tapping point without obstruction. 
     
     
         7 . The sealing device of  claim 5  wherein the porous body is formed from sintered metal or porous ceramics.