The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 23, 1992
Filed:
Jan. 23, 1991
Antony J Wood, Northants, GB;
George F Gocher, Milton Keynes, GB;
Ferranti International plc, , GB;
Abstract
A hydraulic spool valve 40 (FIG. 2(a)) of the edge control type in which the peripheral ends 31, 33 of a spool land 47 cooperate with a radial service port 41 to define by axial spool position the the closure of the port 41 and degree of opening to supply or return port 18, 19. The spool 25 is located in a sleeve 14 itself located in a housing 11 and O-ring seals 22', 22' inhibit leakage between sleeve and housing beyond the seals. Leakage fluid up to the seals exerts a contracting force onto the sleeve and when the spool is in a neutral position closing the service port stiction occurs between the sleeve and the end 36 of the spool land closest to the return port. Both the service port in the sleeve and the spool are constructed such that with the spool in the neutral position the spool groove 48 extends towards the return port so that the end 50 of the groove is at least in line 51 with the O-ring seal 22' and the supporting end region 36 of the spool, inevitably contacting the sleeve, does so at an axial part not subjected to a net contracting fluid pressure.