Full function tractor protection valve

A tractor protection valve comprising:

• a trailer parking brake portion that controls application and release of a trailer parking brake system;
• a trailer service brake portion that controls application and release of a trailer service brake system;
• a stability control portion that controls application of a trailer service brake in response to a stability control signal wherein said trailer parking brake portion, said trailer service brake portion, and said stability control portion are each formed within a common valve body;
• wherein said trailer parking brake portion includes a first inlet port to receive air from a primary air source, a second inlet port to receive air from a secondary air source, a first double check valve located within said common valve body to operate between said first and second inlet ports, a parking brake piston located within a first piston cavity, a parking brake valve disc associated with said parking brake piston, a first outlet port to supply air to release the trailer parking brake system, and a second output port to supply air to re-fill the primary and secondary air sources;
• wherein said trailer service brake portion includes a third inlet port to receive air from the primary air source, a fourth inlet port to receive air from the secondary air source, a fifth inlet port to receive an air signal from a hand control device to be actuated by a user, a second double check valve located within said common valve body to operate between said fourth and fifth inlet ports, a third double check valve located within said common valve body to operate between an output from said second double check valve and said third inlet port, a service brake blocking piston in fluid communication with an output from said third double check valve, a service brake relay piston in fluid communication with an output from said service brake blocking piston, a service brake valve disc associated with said service brake relay piston, and a third output port to supply air to the trailer service brake system;
• wherein said stability control portion includes a solenoid valve mounted within said common valve body, said solenoid valve providing a first condition where air is allowed to pass through said solenoid valve to cooperate with said service brake relay piston to supply air via said third outlet port to apply the trailer service brake system in response to the stability control signal, and a second condition where the solenoid valve blocks air from being supplied to said third outlet port and allows supplied air to be exhausted via an exhaust port;
• and
• a fourth double check valve that that has a pair of fourth double check valve inputs that receive air from the output from said service brake blocking piston and the solenoid valve, respectively, and a fourth double check valve output that supplies air to actuate said service brake relay piston.

A tractor protection valve comprising;

• a trailer parking brake portion that controls application and release of a trailer parking brake system, said trailer parking brake portion including a parking brake control valve disc that cooperates with a parking brake piston movable to an air delivery position in response to air supplied from a tractor park brake dash valve, said parking brake control valve disc, in cooperation with the said parking brake piston, supplies air to an outlet port, said outlet port in fluid communication with the trailer parking brake system;
• a trailer service brake portion that controls application and release of a trailer service brake system, said trailer service brake portion responds to air pressure from a tractor service brake foot valve;
• said trailer service brake portion responding to the service brake foot valve, and pressurized air from the tractor park brake dash valve allows a tractor service brake system to communicate with the trailer service brake system;
• said trailer parking brake portion and said trailer service brake portion are each formed in a common body;
• a service brake relay piston and a service brake valve disc associated with said service brake relay piston, and wherein said service brake relay piston, said service brake valve disc, said parking brake piston, and said parking brake control valve disc are all movable along a common linear path;
• and
• wherein said trailer parking brake portion and said trailer service brake portion are exhausted from said common valve body via a single exhaust passage that extends through said parking brake control valve disc and said service brake valve disc.

A tractor protection valve comprising;

• a trailer parking brake portion that controls application and release of a trailer parking brake system, said trailer parking brake portion including a parking brake control valve disc that cooperates with a parking brake piston movable to an air delivery position in response to air supplied from a tractor park brake dash valve, said parking brake control valve disc, in cooperation with the said parking brake piston, supplies air to an outlet port, said outlet port in fluid communication with the trailer parking brake system;
• a service brake blocking piston cooperating with at least one service brake inlet port and in response to air delivery from the trailer parking brake portion prevents simultaneous application of the trailer service brake system and the trailer parking brake system;
• a trailer service brake portion that controls application and release of the trailer service brake system which includes a service brake control valve disc, that cooperates with a service brake piston movable to a service brake apply position in response to air supplied via said at least one service brake inlet port, a service brake relay piston including an orifice extending between opposed piston surfaces for allowing air to flow from said at least one service brake inlet port through said service brake relay piston and into a service brake outlet port, the service brake piston in fluid communication with an output from the service brake blocking piston;
• said trailer parking brake portion, said trailer service brake portion and said service brake blocking piston are each formed in a common body;
• wherein said service brake relay piston, said service brake control valve disc, said parking brake piston, and said parking brake control valve disc are all movable along a common linear path;
• and
• wherein said trailer parking brake portion and said trailer service brake portion are exhausted from said common valve body via a single exhaust passage that extends through said parking brake control valve disc and said service brake control valve disc.