Full function valve for heavy duty semi-trailer brake systems

A brake system for heavy-duty brake tractor-trailer vehicles, comprising:

• a unitary valve body formed with a plurality of individual ports including control and supply ports, a reservoir port in fluid communication with the supply port, and at least one delivery port;
• a service piston displaceable within the body between rest and operative positions thereof in response to a predetermined pressure of supply air traversing the supply port, the service piston opening the control port in the operative position;
• a modulator piston reciprocally displaceable within the body between respective rest and operative positions in response to a predetermined pressure of control air traversing the control port and operatively connected with the reservoir port to provide fluid communication between the reservoir and delivery ports to gradually actuate service brakes during displacement of the modulator piston toward the operative position;
• at least one ABS piston movable reciprocally within the body upon detecting an ABS event during displacement of the modulator piston to the respective operative positions and being operatively connected therewith to affect displacement thereof for controlling fluid communication between the reservoir and delivery ports until the ABS event terminates;
• and
• a plurality of internal passageways within the valve body in fluid communication with the ports and disposed so as to affect reciprocal displacement of service and modulator pistons in response to a variable flow rate of control and supply air through the control and supply ports, said service piston being displaceable in the rest position upon venting of the supply port to allow full air pressure from the reservoir to be applied to the service brakes in the operative position of the modulator piston.

A brake system for a heavy-duty tractor-trailer vehicle, comprising:

• a unitary valve body;
• a control port formed in the body;
• a supply port formed in the body;
• a reservoir containing a pressurized air and having a reservoir port which is provided in the body in fluid communication with the supply port;
• at least one delivery port formed in the body;
• a service piston displaceable within the body between rest and operative positions thereof in response to a predetermined pressure of supply air traversing the supply port, the service piston opening the control port in the operative position;
• a modulator piston reciprocally displaceable between respective rest and operative positions within the body in response to a predetermined pressure of control air traversing the control port;
• a delivery piston movable by the modulator piston within the body between a rest position and an operative position, which corresponds to the operative position of the modulator piston, the delivery piston providing fluid communication between the reservoir port through delivery ports to actuate service brakes as the delivery piston is displaced from the rest position toward the respective operative position;
• a spring surrounding the delivery piston and exerting a spring force which biases the delivery piston toward the rest position, said modulator piston overcoming the spring force to displace the delivery signal toward the operative position;
• at least one ABS piston actuated upon detecting an ABS event experienced by the service brakes during displacement of the modulator and delivery pistons to the respective operative positions thereof, the ABS piston being movable reciprocally and operatively connected to the delivery piston to control fluid communication between the reservoir and delivery ports until the ABS event terminates;
• and
• a plurality of internal passageways within the valve body in fluid communication with the ports and disposed so as to affect reciprocal displacement of service, modulator and delivery pistons in response to a variable flow rate of control and supply air through the control and supply ports.