Purpose of the breather tube:
1. Pressure Relief: As the transmission operates, it generates heat and pressure due to the movement of fluids and the friction between components. The breather tube provides a controlled path for the release of excess pressure, preventing the transmission from building up too much internal pressure that could cause damage to seals and components.
2. Air Exchange: The breather tube also allows for air exchange between the transmission and the atmosphere. As the fluid level in the transmission changes due to temperature variations or fluid expansion, the breather tube enables air to enter or exit the transmission, ensuring proper fluid levels and preventing the formation of air pockets that can affect transmission performance.
3. Moisture Control: The breather tube helps to prevent the ingress of moisture and contaminants into the transmission. It allows air exchange while acting as a barrier against water, dust, and other external elements, thereby protecting the transmission's internal components.
4. Oil Overflow Prevention: In some cases, the breather tube serves as a safety mechanism to prevent transmission fluid from overflowing. If the fluid level exceeds the recommended amount, the excess fluid may be released through the breather tube, preventing damage to other transmission components and ensuring proper fluid circulation.
For these reasons, automatic transmissions are equipped with a breather tube to manage internal pressure, facilitate air exchange, prevent moisture ingress, and control fluid levels.
