Leak-detecting hydraulic system
AssigneeJ. I. Case Company
InventorsGary C. Marchi, Richard H. Logan
Life of this patent
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Abstract
A leak-detecting hydraulic system is disclosed for operation of a fluid actuator associated with a front-end loader, a backhoe, or a like implement on a material handling device. Notably, the system includes a leak-detection circuit which normally acts to prevent movement of the implement associated with the actuator by gravity in the event of a failure in one of the hydraulic fluid lines operatively connected with the actuator. Additionally, the system preferably includes a selectively operable float valve which permits fluid flow which bypasses the leak-detection circuit, thus desirably permitting operation of the implement associated with the actuator in a "floating" mode.
Claims5
A leak-detecting hydraulic system for selectively operating a fluid actuator having first and second opposing expansible chambers, comprising:
- selectively operable, multi-position control valve means for directing pressurized hydraulic fluid to a selected one of said chambers while receiving fluid from the other of said chambers;
- first fluid passage means joining said first chamber and said control valve means in fluid communication;
- and
- second fluid passage means for joining said second chamber and said control valve means in fluid communication, said second passage means including leak-detection circuit means comprising one-way valve means for permitting pressurized fluid flow into said second chamber while preventing reverse fluid flow through said one-way valve means, and counterbalanced valve means arranged in parallel flow relation with said one-way valve means, first and second pressure-sensing lines respectively joining, in pressure-sensing relation said first fluid passage means and said second expansible chamber with said counterbalanced valve means, said counterbalanced valve means including biasing means acting in opposition to said first and second pressure-sensing lines, whereby said leak-detection circuit means being adapted to permit pressurized fluid flow from said valve means to said second chamber via said circuit means, and being further adapted to prevent fluid flow from said second chamber via said circuit means unless said first fluid passage means is pressurized with fluid.
A fluid actuator having leak-detection means, comprising:
- cooperating cylinder means and piston means defining opposing first and second expansible chambers;
- first fluid flow passage means in fluid communication with said first chamber for directing pressurized fluid to said first chamber and for receiving fluid therefrom;
- second fluid flow passage means in fluid communication with said second chamber for directing pressurized fluid to said second chamber and for receiving fluid therefrom,
- said second passage means including leak-detection circuit means operatively associated with said first passage means,
- said leak-detection circuit means comprising a one-way flow check valve for permitting pressurized fluid flow into said second chamber and preventing reverse fluid flow through check valve, and counterbalanced valve means disposed in parallel flow relation with said check valve, said counterbalanced valve means being operatively connected, in pressure-sensing relation, with said first passage means and second second chamber through first and second pressure-sensing lines, respectively, said counterbalanced valve means including biasing means acting in opposition to said first and second pressure-sensing lines whereby fluid pressurization of said first passage means operates to position said counterbalanced valve means in an open condition to permit fluid flow from said second chamber through said counterbalanced valve means, and
- said circuit means permits pressurized fluid flow into said second chamber via said circuit means, and is further adapted to permit fluid flow from said second chamber through said circuit means only when the cumulative fluid pressure in said second chamber and first passage means exceeds a predetermined value.
Dependencies are inferred from the claim text.