Transmission pressure controlled vent system

A transmission having a pressure controlled vent system, comprising:

• a transmission housing defining an internal cavity, wherein the transmission is sealed to prevent fluid communication between the internal cavity and an external atmosphere;
• a pressure relief valve in fluid communication with an upper portion of the internal cavity, wherein the pressure relief valve is configured to vent a transmission air within the upper portion of the internal cavity to an external atmosphere when a predetermined pressure differential between the internal cavity and atmosphere is exceeded;
• a vacuum relief valve in fluid communication with the upper portion of the internal cavity, wherein the vacuum relief valve is configured to vent an external air into the internal cavity when a predetermined vacuum differential between the internal cavity and the external atmosphere is exceeded;
• a vent tube having:
• a first end defining a first opening in fluid communication with the upper portion of the internal cavity;
• a second end defining a second opening in fluid communication with the external atmosphere;
• and
• a bifurcated portion between the first end and the second end, wherein the bifurcated portion includes a first tube segment and a second tube segment in parallel with the first tube segment,
• wherein the pressure relief valve is disposed in-line with the first tube segment and the vacuum relief valve is disposed in-line with the second tube segment;
• and
• a moisture trap in fluid communication with the second tube opening, wherein the moisture trap is configured to condense a water vapor entering the vent tube from the external atmosphere and to re-evaporate the condensed water vapor, wherein the moisture trap includes:
• a moisture trap housing comprising a dry-air opening in fluid communication with the second opening of the vent tube, an interior surface defining an interior volume, and a lid portion having a moisture tube extending into the interior volume, wherein the moisture tube is in fluid communication with the external atmosphere;
• an evaporator cup concentrically disposed within the interior volume and spaced from the interior surface of the moisture trap housing, wherein the evaporator cup includes an inward tapered lid defining a circumferential opening surrounding the moisture tube;
• and
• an annular passageway defined between the evaporator cup and the interior surface of the moisture trap housing.