192 clutches and power-stop control – Vortex-flow drive and clutch – With brake
Patent
1980-10-01
1983-03-15
Krizmanich, George H.
192 clutches and power-stop control
Vortex-flow drive and clutch
With brake
192 4C, B60K 4126
Patent
active
043764746
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to brakes and in particular to hydraulic brakes as used in vehicles.
2. Background Art
In vehicles, such as tractors, hydraulic parking brakes are utilized which are applied when the transmission shift lever is placed in the neutral position. Over a period of time, air may become entrained in the brake fluid, possibly causing erratic or inconsistent braking operation.
In one conventional form of tractor vehicle utilizing such brakes, the brake fluid comprises a pressurized transmission replenishing circuit fluid. Conventionally, when the speed and direction control lever of the vehicle is in forward or reverse positions, the transmission fluid replenishing pressure overcomes the spring biasing of the hydraulic brakes to maintain the brakes released. When the speed and direction control lever is placed in the neutral position, the transmission replenishing pressure drops, permitting the brakes to become spring-applied and, thus, serve as parking brakes for the vehicle.
It has been conventional to provide means in association with the brakes to permit bleeding thereof to eliminate entrapped air from the brake which may collect in an upper portion thereof. One conventional form of bleeding means comprises a manual valve on the upper, or bleeder, line connected to the brake. To bleed the brake, the valve is opened and the transmission is engaged to pressurize the brakes. Such an operation may result in vehicle movement.
In such vehicle installations, it is further desirable, from time to time, to apply pressure to the brakes so as to release the brake notwithstanding the de-energization of the transmission fluid pressurizing means, such as when the vehicle is being towed. For this purpose, a special manually operable pump has been provided in combination with the bleeding means.
DISCLOSURE OF INVENTION
The present invention comprehends an improved brake system which provides automatic self-bleeding of the brake as a concomitant of normal operation of the vehicle.
More specifically, the invention comprehends the provision of means for bleeding air from the brake fluid as an incident of placing the transmission in the neutral mode.
The invention further comprehends the provision of means for flushing debris from a lower portion of the brake also as an incident of placing the transmission in the neutral mode.
The invention utilizes the spring means of the hydraulic brake as a means for forcing outwardly from the pressure chamber of the brake a quantity of the hydraulic brake fluid each time the brake fluid pressure is reduced, as by placing the transmission control lever in the neutral position.
More specifically, the invention comprehends the provision of means for passing outwardly from an upper portion of the pressure chamber a quantity of the hydraulic fluid and air collected therein for subsequent delivery to venting means eliminating the air from the liquid.
More specifically, the invention comprehends the provision in a brake system of a hydraulic brake provided with spring means for applying the brake and fluid pressure responsive means for overcoming the spring means for releasing the brake, the pressure responsive means defining a pressure chamber having a lower portion and an upper portion, a hydraulic liquid inlet to the lower portion, a control for selectively directing pressurized hydraulic liquid through the inlet to release the brake, and means for effecting self bleeding of the brake including a bleed outlet opening to the upper portion of the brake pressure chamber and connected parallel with the inlet, the outlet having a check valve permitting flow only outwardly from the upper portion of the brake pressure chamber whereby hydraulic liquid may pass into the pressure chamber only through the inlet, hydraulic liquid only is passed outwardly through the inlet and hydraulic liquid and air which may collect in the upper portion of the brake pressure chamber are passed outwardly through the bleed outlet by the action of the spring means when
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patent: 2725128 (1955-11-01), Martin
patent: 2924984 (1960-02-01), McFarland
patent: 3136399 (1964-06-01), Granryd
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patent: 3635317 (1972-01-01), Crabb
patent: 3854599 (1974-12-01), Talak et al.
patent: 4020932 (1977-05-01), Windish
patent: 4024936 (1977-05-01), Crabb
patent: 4057297 (1977-11-01), Beck et al.
patent: 4307917 (1981-12-01), Hasselbacher et al.
Piper Hugh V.
Tunnell James H.
Caterpillar Tractor Co.
Krizmanich George H.
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