초록 ▼

A load supporting hydraulic system having main control valve provided with a load check valve and a vent valve; the load check valve, which has a hose connection to the main control valve, is operative to permit free flow of fluid from the control valve toward the load supporting chamber of the syst

A load supporting hydraulic system having main control valve provided with a load check valve and a vent valve; the load check valve, which has a hose connection to the main control valve, is operative to permit free flow of fluid from the control valve toward the load supporting chamber of the system and to block fluid flow from the load supporting chamber toward the control valve, whereas the vent valve is operative with the control valve to permit the load check valve to be opened by fluid pressure from the load supporting chamber to allow fluid flow therefrom thru the hose connection and control valve to drain. A cancelling valve is added to the system to override the vent valve upon failure of the hose connection and reblock fluid flow from the load supporting chamber toward the hose connection and control valve.

대표청구항 ▼

In a fluid circuit system comprising a fluid motor (2) for raising and supporting a load having a load supporting chamber (5) in the motor, a master directional control valve (15) for selectively communicating pressurized fluid between a pressure fluid source (10,11) and said motor in correspondence

In a fluid circuit system comprising a fluid motor (2) for raising and supporting a load having a load supporting chamber (5) in the motor, a master directional control valve (15) for selectively communicating pressurized fluid between a pressure fluid source (10,11) and said motor in correspondence with raise, lower, and load hold positions of the valve first named, and a second load check (42) valve hydraulically disposed between the first named valve and said motor for affording free flow of fluid from the first named valve to said motor and having a normal fluid blocking position for blocking flow of fluid from said motor to the first named valve, the improved combination with the first (15) and second (42) valves of: service connections including a flexible transfer line (22) to carry the flow afforded by the first named valve between it and the second valve and loaded motor and essential thereto in raising, lowering, and holding the load; said second valve having a control chamber (54) which, when vented, effects opening of said second valve to afford a routing of fluid of said load supporting chamber for its flow to and thru the flexible transfer line and which includes restriction means (55) in communication with said load supporting chamber, and said second valve being responsive to fluid pressure in said load supporting chamber to bias said second valve to said fluid blocking position thereby obstructing all flow to the flexible transfer line; and means (34) connected to said transfer line responsive to a flow characteristic attendant with line rupture to cancel venting of said control chamber for affording fluid biasing the second valve to said fluid blocking position.