Power plants – Pressure fluid source and motor – Apparatus having means responsive to or ameliorating the...
Statutory Invention Registration
1998-10-15
2001-04-03
Tudor, Harold J. (Department: 3641)
Power plants
Pressure fluid source and motor
Apparatus having means responsive to or ameliorating the...
C303S115600, C477S199000
Statutory Invention Registration
active
H0001953
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to an apparatus and method for preparing a hydraulic work machine for towing and, more particularly, to an apparatus and method for raising a work implement and releasing a parking brake under dead engine conditions.
BACKGROUND ART
Hydraulic work machines, in particular mobile machines such as wheel loaders, tractors, scrapers, graders, and the like, are used extensively to perform work functions such as altering terrain, moving material, constructing roads, lots, runways, and repairing the same. Generally these hydraulic work machines have a power source, i.e., an engine, to move about, and this same power source is also used to power the hydraulic systems on the machine.
Occasionally, an engine will malfunction on a machine, thus disabling the machine from moving about, and also disabling the hydraulic systems. It is common for such a machine to use a spring applied, hydraulic pressure released brake system; that is, the brakes are always engaged by spring action until controlled hydraulic pressure to the brakes overcomes the spring force and releases the brakes. In a dead engine situation, the brakes will be engaged. If the machine is required to be towed, some means is needed to release the brakes for towing.
Several patents exist which disclose methods for releasing brakes for towing under dead engine conditions. For example, in U.S. Pat. No. 4,195,716, Wirt discloses a brake release mechanism for vehicle towing which uses a manual hydraulic pump means to manually pump fluid into the brake system and thus disengage the brakes for towing. Although the system disclosed by Wirt accomplishes the purpose of releasing the brakes, some significant effort is required by a human to perform this procedure. What is needed is a means to release the brakes for towing while minimizing the human effort required.
In addition to the need to release the brakes for towing under dead engine conditions, it often occurs that a work implement is in contact with the ground when the engine fails. In this situation, the implement would need to be raised above the ground to prepare the machine for towing. The hydraulic pressure required to raise an implement, particularly a heavy implement or an implement with a heavy load, would be tremendous. For example, a compactor/hammer mounted on a wheel loader may weigh in excess of 14,000 kg. Historically, an implement is raised for towing by either manually pumping hydraulic fluid into lift cylinders or by connecting a pump from a service vehicle to the disabled work machine and then pumping hydraulic fluid into the lift cylinders. In either case, it is desired to enable lifting of an implement for towing by some convenient means located within easy access to an operator, and without requiring the manual connection of some other system.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention an apparatus for preparing a hydraulic work machine for towing in response to a dead engine condition is disclosed. The apparatus includes a source of hydraulic fluid, a standby pump system hydraulically connected to the source, a plurality of pilot controls adapted for electrical activation by the standby pump system, and a hydraulic brake system. The apparatus also includes a supply valve connected to the pilot controls, and at least one lift cylinder connected to the supply valve and adapted to lift an implement on the work machine. The hydraulic brake system and the lift cylinder are enabled for hydraulic control in response to activation of the standby pump system.
In another aspect of the present invention an apparatus for lifting an implement on a hydraulic work machine in response to a dead engine condition is disclosed. The apparatus includes a source of hydraulic fluid, a standby pump system hydraulically connected to the source, and a plurality of pilot controls adapted for electrical activation by the standby pump system. The apparatus also includes a supply valve connected to the pilot controls, and at least one lift cylinder connected to the supply valve and adapted to lift an implement on the work machine. The lift cylinder is enabled for hydraulic control in response to activation of the standby pump system.
In yet another aspect of the present invention an apparatus for releasing a set of hydraulically actuated brakes on a hydraulic work machine in response to a dead engine condition is disclosed. The apparatus includes a source of hydraulic fluid, a standby pump system hydraulically connected to the source, and a hydraulic brake system. The apparatus also includes a sequence valve adapted to controllably deliver hydraulic fluid to the hydraulic brake system. The hydraulic brake system is enabled for hydraulic control in response to activation of the standby pump system.
In yet another aspect of the present invention a method for preparing a hydraulic work machine for towing in response to a dead engine condition is disclosed. The method includes the steps of depressing a switch to activate a standby pump system, activating a motor in response to depressing the switch, activating a hydraulic pump in response to activating the motor, lifting an implement as a function of the switch being depressed and in response to engaging a hydraulic implement lift control lever, and releasing a set of brakes as a function of the switch being depressed and in response to engaging a brake release lever.
REFERENCES:
patent: 3944295 (1976-03-01), Lloyd et al.
patent: 3987703 (1976-10-01), Latimer
patent: 4195716 (1980-04-01), Wirt
patent: 4392415 (1983-07-01), Melocik
patent: 4509406 (1985-04-01), Melocik
patent: 4576418 (1986-03-01), Holzinger et al.
Burckhartzmeyer Jerry J.
Dezelan, Jr. Joseph E.
Vogt Bryan A.
Caterpillar Inc.
Lundquist Steve D.
Tudor Harold J.
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