Trailer spring brake valve

A valve for use in a truck-trailer system having a source of air under pressure, a reservoir, at least one spring brake unit and a brake service line, the valve comprising:

• a body having a supply passage in communication with the associated source of air under pressure;
• a pressure protection valve portion operably disposed within a first chamber of the body, the first chamber having an inlet for communication with the supply passage and an outlet for communication with the reservoir, the pressure protection valve portion configured to selectively block the flow of pressurized air from the supply passage through the first chamber to the reservoir until a predetermined pressure is reached;
• a spring brake actuation valve portion operably disposed within a second chamber of the body, the second chamber having an inlet for communicating with the supply passage, at least one delivery outlet passage in selective communication with the at least one spring brake unit and an exhaust outlet in selective communication with the at least one spring brake unit, the spring brake actuation valve portion controlling pressurized air flow toward the at least one spring brake unit and the exhaust outlet;
• and
• an anti-compounding valve portion operably disposed within a third chamber of the body for preventing simultaneous application of the at least one spring brake unit and at least one service brake unit, the third chamber having a first inlet in communication with the supply passage, a second inlet in communication with the brake service line and a first outlet in communication with the first chamber and a second outlet in communication with the second chamber, the anti-compounding valve portion preventing flow of pressurized air from the brake service line towards the spring brake actuation valve portion;
• wherein the anti-compounding valve portion includes a second valve member deflectable in a first direction for permitting air flow from the supply passage to the first and second chambers and in a second direction for permitting air flow from the brake service line to the supply passage;
• and
• wherein the second valve member includes an annular portion having a first surface in sealing engagement with a third chamber first valve seat and a second surface in sealing engagement with a third chamber second valve seat, the first surface being subject to pressure from the supply passage, the second surface being subject to pressure from the service brake line, wherein upon pressure from the brake service line, the second valve member moves away from the second valve seat, the air from the service brake line venting out of the supply passage.

A valve for use in a pneumatic system of a truck-trailer having a source of air under pressure, a reservoir, at least one spring brake unit and a brake service line, the valve comprising:

• a housing including:
• a supply passage in communication with the source of air under pressure,
• at least one delivery passage in communication with the supply passage and the spring brake unit,
• an exhaust passage in communication with the spring brake unit,
• a reservoir passage in communication with the supply passage and the reservoir, and
• a service passage in communication with the brake service line and the supply passage;
• a pressure protection valve means disposed within a first chamber of the housing for selectively blocking the flow of pressurized air from the supply passage to the reservoir through the reservoir passage until a predetermined pressure is reached;
• a spring brake actuation valve means disposed within a second chamber of the housing for controllably allowing pressurized air flow toward one of the delivery passage and the exhaust passage, the spring brake actuation valve means including a pre-stressed quick release diaphragm;
• and
• an anti-compounding valve means disposed within a third chamber defined by the housing for preventing simultaneous application of the air spring brake unit and service brake unit, the anti-compounding valve means preventing flow of pressurized air from the brake service line towards the pre-stressed quick release diaphragm;
• wherein the anti-compounding valve means includes a valve member that includes an annular portion having a first surface in sealing engagement with a third chamber first valve seat and a second surface in sealing engagement with a third chamber second valve seat, the first surface being subject to pressure from the supply passage, the second surface being subject to pressure from the service brake line.