Fluid-pressure and analogous brake systems – Multiple systems – Fluid pressure and electric
Utility Patent
1998-06-12
2001-01-02
Graham, Matthew C. (Department: 3613)
Fluid-pressure and analogous brake systems
Multiple systems
Fluid pressure and electric
C303S015000, C303S901000
Utility Patent
active
06168244
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to a park brake release apparatus for releasing a park brake. In particular, the invention relates to a park brake release apparatus which allows an operator to release the park brake, without engine power, by pumping a service brake pedal.
BACKGROUND OF THE INVENTION
Agricultural machines, such as harvesting combines and cotton pickers, typically have a hydraulically operated parking brake which can be set and released from inside the cab when the engine is running. However, if there is no engine power, and the park brake is set, there is typically no way to release the brake from the inside of the cab. Instead, the brake must be released manually from a position outside of the cab. This is typically done by manually pumping grease to the park brake pistons of the park brake via a tow valve which is located adjacent the cab deck.
There are several disadvantages to this approach. Since the tow valve is located outside of the cab, the park brake cannot be released conveniently from inside of the cab. Moreover, the grease which must be pumped to the park brake pistons may contaminate the hydraulic system. In particular, the viscosity of the grease is much higher than the hydraulic oil, and as a result, the components of the hydraulic system may become fouled and the speed of the brake functions may decrease. Furthermore, cold grease may cause a relief valve (which is used to protect the hydraulic system from over pressurization) to open before the park brake is released. Finally, a complete set of tools, including a grease gun and wrenches, are required to access the tow valve and manually release the park brake.
Accordingly, it would be desirable to have a park brake release apparatus that overcomes the disadvantages described above, and to provide a simple and cost effective park brake release apparatus.
SUMMARY OF THE INVENTION
One aspect of the invention provides a park brake release apparatus including a service brake valve assembly operably connected to a service brake piston. A one-way valve is operably connected between the service brake piston and a park brake piston to allow fluid to flow from the service brake valve assembly to the park brake piston to release a park brake. The fluid may preferably be hydraulic fluid. The one-way valve may preferably be rated at approximately 5 pounds per square inch. The service brake valve assembly may include at least one service brake pedal for flowing fluid from the service brake valve assembly to the park brake piston. The service brake pedal may be comprised of a left service brake pedal or a right service brake pedal. The service brake piston may be comprised of a left service brake piston and a right service brake piston. The park brake piston may be comprised of a left park brake piston and a right park brake piston. The one-way valve may be operably connected between the left service brake piston and the left park brake piston to allow fluid to flow from the service brake valve assembly to the left park brake piston and the right park brake piston to release the park brake. Alternatively, the one-way valve may be operably connected between the right service brake piston and the right park brake piston to allow fluid to flow from the service brake valve assembly to the right park brake piston and the left park brake piston to release a park brake. A park brake valve assembly may include a park brake valve. The park brake valve may preferably be a park brake solenoid valve. The park brake valve assembly may preferably be connected to the park brake piston. A park brake switch may be operably connected to the park brake valve to prevent fluid from flowing through the park brake valve assembly to a tank when the park brake switch is in the “off” position.
Another aspect of the invention provides a park brake release apparatus which includes a service brake valve assembly and a service brake piston. A service brake line connects the service brake valve assembly to the service brake piston. A park brake line connects a park brake valve assembly to a park brake piston. A one-way valve is connected between the service brake line and the park brake line to allow fluid to flow from the service brake line to the park brake line to release a park brake. The park brake valve assembly may include a park brake valve which may preferably be a park brake solenoid valve. A park brake switch may be operably connected to the park brake valve to prevent fluid from flowing through the park brake valve assembly to a tank when the park brake switch is in the “off” position. The service brake valve assembly may include at least one service brake pedal for pumping fluid from the service brake valve assembly to the park brake piston.
Another aspect of the invention provides a method of releasing a park brake on a machine which has no engine power. A service brake valve assembly is provided. A service brake piston is operably connected to the service brake valve assembly. A one-way valve is operably connected between the service brake piston and a park brake piston. A brake pedal is pumped and fluid is flowed from the service brake valve assembly to the park brake piston to release a park brake. The fluid may preferably be hydraulic fluid. A park brake valve assembly including a park brake valve may be provided. Fluid may preferably be prevented from flowing through the park brake valve assembly to a tank while pumping the brake pedal. A park brake switch operably connected to the park brake valve may be provided. The park brake switch may preferably be turned to the “off” position.
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Brinks Hofer Gilson & Lione
Case Corporation
Graham Matthew C.
Nguyen Lan
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