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1. EP0036761 - FLUID CIRCUIT WITH LOAD CHECK VALVE

Office
European Patent Office
Application Number 81301185
Application Date 19.03.1981
Publication Number 0036761
Publication Date 30.09.1981
Publication Kind A3
IPC
F15B 11/08
FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
11Servomotor systems without provision for follow-up action
08with only one servomotor
F15B 13/01
FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
13Details of servomotor systems
01Locking-valves or other detent devices
CPC
F15B 13/01
FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
13Details of servomotor systems
01Locking-valves or other detent ; i.e. load-holding; devices
Applicants CATERPILLAR TRACTOR CO.
Inventors BIANCHETTA, DONALD L.
Designated States
Priority Data 8000321 24.03.1980 US
Title
(DE) Hydraulischer Kreislauf mit R├╝ckschlagventil.
(EN) FLUID CIRCUIT WITH LOAD CHECK VALVE
(FR) Circuit hydraulique avec clapet anti-retour.
Abstract
(EN)
The spool-type load check valve (20) of this invention, used in conjunction with additional check valves (60, 61) overcomes the problem of leakage in conventional spool type check valves by providing a series of interconnecting passages and chambers (36) for communicating equalized fluid pressure from a cylinder (11) to either end of the spool (27) thereof to provide for minimal leakage. When a pair of such cylinders (11, 12) are utilized, the load check valves (20, 20 min ) associated therewith are interconnected by a balance line (50) and resolver valves (47 min ) ensure equalization of fluid pressure in the cylinders upon actuation thereof and also a gradual descent of a load carried by the cylinders upon loss of fluid pressure between the check valves.