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:
Jan. 31, 1995
Filed:
Jun. 03, 1993
Kenneth G Cleasby, Chichester, GB;
Trinova Limited, Sussex, GB;
Abstract
An electrically operated, two-stage hydraulic spool valve comprising a maid stage (2) having a main spool (4), centering springs (9) acting on the main spool, a pilot stage (1) having a pilot spool (12), and two solenoids (39) acting on respective ends of the pilot spool to control the operating position of the latter the solenoid being opposed by return springs (18) also acting on respective ends of the pilot spool, the pilot stage comprising tank port means (23,24), supply port means (26), and two service ports (27,28), and the pilot spool comprising two portions (13,14), a spring (15) interposed between the two portions and operable to urge the two portions apart in a direction axially of the pilot spool so that on de-energization of the solenoids, the portions of the pilot spool separate under the action of the spring to provide an interconnection between the pilot service ports and the tank port means. The tank port means comprise two tank ports (23,24) between which the two service ports (27,28) are disposed, and the supply port means (26) comprises two supply ports (26a,26b) disposed between the service ports (27,28) and spaced apart by an amount such that, in normal operation of the pilot valve, neither supply port sees the ends of the two portions of the pilot spool which are maintained in contact by the operation of the solenoids (39).