Control for dead engine lower
AssigneeCaterpillar Tractor Co.
InventorKurt B. Melocik
Life of this patent
Estimating the term…
Abstract
A mechanism (80) is provided to controllably lower an actuator (28) upon the loss of a source (62) of pilot fluid in a fluid system requiring a float condition of operation. A resolver (80) is located in a vent line of a make-up valve and is connected to a second load supporting end (32) of the actuator (28) and is controllably vented to a tank (38) by moving a pilot control valve (48) to a fourth position (D). This eliminates the need to provide complicated systems having pilot operated check valves which are more difficult to control.
Claims2
In a fluid system (10) having a fluid source (12), a tank (38), an actuator (28) having a first end (30) and a second load supporting end (32);
- a pilot operated control valve (14) having first and second ends (66,70) and being connected to said source (12) and said actuator (28);
- a source of pilot fluid (62);
- a pilot control valve (48) connected to said source of pilot fluid (62) and said first and second ends (66,70) of the pilot operated control valve (14) and movable between at least one operating position and a float position;
- a make-up valve (42) connected between the first end (30) of the actuator (28) and the main control valve (14), a vent line (74) connected to the make-up valve (42) and the pilot control valve (48) and being in communication with the tank (38) at the float position (D) of the pilot control valve (62);
- the improvement comprising:
- means (79) for communicating the second load supporting end (32) of the actuator (28) to the tank (38) only through said vent line (74) and said pilot control valve (48) in response to loss of said source of pilot fluid (62) and said pilot control valve (48) being moved to said float position (D) so that the second load supporting end (32) can be vented to the tank (38) at a controlled rate regardless of the pressure of the fluid in the second load supporting end.
In a fluid system (10) having a fluid source (12), a tank (38), an actuator (28) having a first end (30) and a second load supporting end (32);
- a pilot operated control valve (14) having first and second ends (66,70) and being connected to said source (12) and said actuator (28);
- a source of pilot fluid (62);
- a pilot control valve (48) connected to said source of pilot fluid (62) and said first and second ends (66,70) of the pilot operated control valve (14) and movable between at least one operating position and a float position;
- a make-up valve (42) connected between the first end (30) of the actuator (28) and the main control valve (14), a vent line (74) connected to the make-up valve (42) and the pilot control valve (48) and being in communication with the tank (38) at the float position (D) of the pilot control valve (62), said vent line (74) includes first and second conduits (76,78), said first conduit (76) being connected to said make-up valve (42) and said second circuit (78) being connected to said pilot control valve (48);
- the improvement comprising;
- a resolver valve (80) and a third conduit (88) adapted to communicate the second load supporting end (32) of the actuator (28) to the tank (38) through said vent line (74) and said pilot control valve (48) in response to loss of said source of pilot fluid (62) and said pilot control valve (48) being moved to said float position (D), said third conduit (88) being connected to said second load supporting end (32) and said resolver valve (80) being located in said vent line (74) between said first and second conduits (76,78) and having a first inlet port (82) connected to said first conduit (76), a second inlet port (84) connected to said third conduit (88) and an outlet port (86) connected to said second conduit (78).
Dependencies are inferred from the claim text.