Brake system

Claim 2

A brake system for stopping rotation of a pair of independently rotatable elements of a vehicle, comprising; fluid applied brake means operatively associated with one of said rotatable elements; spring applied, fluid released brake means operatively associated with the other of said rotatable elements; apparatus means for providing pressurized fluid; conduit means connecting said apparatus means to both of said brake means; and valve means disposed in said conduit means and normally positioned to direct said pressurized fluid to said spring applied fluid released brake means while blocking fluid flow therethrough to the fluid applied brake means for releasing both of said brake means permitting unrestricted rotation of said elements, said valve means being selectively positionable simultaneously to block fluid flow therethrough to said spring applied fluid released brake means and to direct pressurized fluid to said fluid applied brake means so that both of said brake means are applied at the same time for stopping rotation of said rotatable elements.

Claim 3

The brake system of claim 1 wherein said valve means includes a manual control valve selectively positionable for blocking said pressurized fluid from said spring applied fluid released brake means, and a fluid actuated inversion valve positioned to direct said pressurized fluid to said fluid applied brake means in response to the blocking of pressurized fluid to the spring applied fluid released brake means.

Claim 4

The brake system of claim 2 wherein said apparatus means includes a hydraulic pump for supplying pressurized hydraulic fluid to said spring applied fluid released brake means through said conduit means, and including a fluid actuated modulating valve positioned in response to pressurized fluid directed thereto from said manual control valve to direct said hydraulic fluid to the spring applied fluid released brake means and positioned in response to the blocking of said pressurized fluid thereto from said manual control valve to block hydraulic fluid from said spring applied fluid released brake means.

Claim 5

The brake system of claim 3 wherein said apparatus means includes a tank of compressed air and wherein said pressurized fluid directed through said manual control valve for shifting the inversion and modulating valves is pressurized air and said pressurized fluid directed through said inversion valve is pressurized air.

Claim 6

The brake system of claim 4 including a master cylinder having a fluid chamber, and actuator means for generating fluid pressure in said fluid chamber in response to pressurized air directed to said master cylinder, said conduit means includes a conduit connecting said fluid chamber with said fluid applied brake means.

Claim 7

The brake system of claim 5 including second fluid applied brake means operatively associated with said other rotatable element, and means for directing pressurized fluid to said second brake means for application thereof.

Claim 8

The brake system of claim 6 wherein said fluid directing means includes a tank of compressed air, a master cylinder having a fluid chamber and actuator means for generating fluid pressure in said fluid chamber in response to pressurized air directed to said master cylinder, a fluid conduit connecting said fluid chamber to said second brake means, an air conduit connecting said tank with said master cylinder and valve means disposed in said air conduit for controlling flow of pressurized air to said master cylinder.

Claim 9

The brake system of claim 7 including a towing valve disposed in said fluid conduit having a position permitting fluid flow from said fluid chamber to said second fluid applied brake means, said towing valve being selectively positionable to direct pressurized fluid from said fluid chamber through said conduit means to release said spring applied fluid released brake means when said hydraulic pump is inoperative.

Claim 10

A brake system for stopping rotation of a rotatable member comprising; a spring applied hydraulically released brake operatively associated with such rotatable member; pump means for generating hydraulic fluid pressure; a fluid conduit communicating said pump with said brake means; an air actuated modulating valve disposed in said fluid conduit for controlling fluid flow therethrough, said modulating valve normally positioned for blocking fluid flow through said fluid conduit; a tank of compressed air; air conduit means communicating said tank with said modulating valve; and a manual control valve disposed in said air conduit means and normally positioned to direct pressurized air through said air conduit means to actuate said modulating valve to a position to direct pressurized fluid to said brake means for releasing said brake means, said manual control valve being selectively positionable modulatably to reduce air flow through said air conduit means for shifting the modulating valve toward the normal fluid blocking position to modulatably reduce fluid flow to the brake means for applying said brake means for stopping rotatIon of the rotatable member.

Claim 11

A brake system for stopping rotation of a rotatable member comprising; a spring applied hydraulically released brake operatively associated with such rotatable member; pump means for generating hydraulic fluid pressure; a fluid conduit communicating said pump with said brake means; an air actuated modulating valve disposed in said fluid conduit for controlling fluid flow therethrough, said modulating valve normally positioned for blocking fluid flow through said fluid conduit; a tank of compressed air; air conduit means communicating said tank with said modulating valve; and a manual control valve disposed in said air conduit means and normally positioned to direct pressurized air through said air conduit means to actuate said modulating valve to a position to direct pressurized fluid to said brake means for releasing said brake means, said manual control valve being selectively positionable modulatably to reduce air flow through said air conduit means for shifting the modulating valve toward the normal fluid blocking position to modulatably reduce fluid flow to the brake means for applying said brake means for stopping rotatIon of the rotatable member.

Claim 12

The brake system of claim 9 including a fluid applied brake operatively associated with the rotatable member, a pair of master cylinders each having a fluid chamber and actuator means for generating fluid pressure in said fluid chamber in response to pressurized air directed to said master cylinders, fluid conduit means communicating said fluid chambers with said fluid applied brakes, a check valve disposed in said conduit means and operative to communicate pressurized fluid to the fluid applied brake from the fluid chamber which has the highest fluid pressure therein while blocking direct communication between the fluid chambers, air conduit means connecting said tank with said master cylinders, service valve means disposed in said air conduit means for controlling flow of pressurized air from said tank to one of said master cylinders for controlling actuation of said fluid applied brakes, and retarder valve means disposed in said air conduit means in parallel to said service valve means for controlling flow of pressurized air from the tank to the other of said master cylinders for providing a second method of actuating the fluid applied brakes.

Claim 13

The brake system of claim 10 wherein the rotatable member is a wheel of a vehicle and including a control valve disposed in said fluid conduit means and selectively positionable to connect said fluid conduit means to said fluid conduit for providing a second source of pressurized fluid to release said spring applied fluid released brake to permit the vehicle to be towed when said pump means is inoperative.

Claim 14

A brake system for a vehicle comprising; a first source of pressurized fluid; a spring applied fluid released brake which is automatically applied in the absence of actuating fluid thereto, a fluid conduit connecting said first source of pressurized fluid to said spring applied fluid released brake; valve means disposed in said fluid conduit and having a position for directing pressurized fluid to said spring applied fluid released brake releasing said spring applied fluid released brake, said valve means being selectively positionable to block fluid flow to said spring applied released brake; a second source of pressurized fluid; a fluid applied brake; conduit means connecting said second source of pressurized fluid to said fluid applied brake; valve means disposed in said conduit means for controlling flow of pressurized fluid therethrough and selectively positionable to direct pressurized fluid through said conduit means to apply said fluid applied brake; and a towing valve disposed in said conduit means having a first position for communicating said pressurized fluid from said second source of pressurized fluid to said fluid applied brake and selectively positionable to connect said conduit means to said fluid conduit for communicating said pressurized fluid from said second source of pressurized fluid to said spring applied fluid released brake for releasing said spring applied fluid released brake to permit the vehicle to be towed in the absence of pressurized fluid from first source of pressurized fluid.

Claim 15

A brake system for a vehicle comprising; a first source of pressurized fluid; a spring applied fluid released brake which is automatically applied in the absence of actuating fluid thereto, a fluid conduit connecting said first source of pressurized fluid to said spring applied fluid released brake; valve means disposed in said fluid conduit and having a position for directing pressurized fluid to said spring applied fluid released brake releasing said spring applied fluid released brake, said valve means being selectively positionable to block fluid flow to said spring applied released brake; a second source of pressurized fluid; a fluid applied brake; conduit means connecting said second source of pressurized fluid to said fluid applied brake; valve means disposed in said conduit means for controlling flow of pressurized fluid therethrough and selectively positionable to direct pressurized fluid through said conduit means to apply said fluid applied brake; and a towing valve disposed in said conduit means having a first position for communicating said pressurized fluid from said second source of pressurized fluid to said fluid applied brake and selectively positionable to connect said conduit means to said fluid conduit for communicating said pressurized fluid from said second source of pressurized fluid to said spring applied fluid released brake for releasing said spring applied fluid released brake to permit the vehicle to be towed in the absence of pressurized fluid from first source of pressurized fluid.

Claim 16

The brake system of claim 12 wherein said first source of pressurized fluid is a hydraulic pump.

Claim 17

The brake system of claim 13 wherein said second source of pressurized fluid includes a tank of compressed air and a master cylinder having a fluid chamber and actuator means for generating fluid pressure in said fluid chamber in response to pressurized air directed to said master cylinder, said conduit means include a fluid conduit connecting said fluid chamber with said fluid applied brake, and an air conduit connecting said tank of compressed air with said master cylinder, said valve means being disposed in said air conduit with said towing valve being disposed in said fluid conduit.

Claim 18

The brake system of claim 14 wherein said valve means includes an air actuated relay valve disposed Within said air conduit, an air line connected to said tank of compressed air for delivering actuating air to said relay valve, and a manual control valve disposed in said air line selectively positionable for controlling flow of pressurized air through said line for actuating said relay valve.