The Hydraulic system is actually a complex maze of passages and tubes that transfer transmission fluid under high pressure to all other parts of the transmission and torque converter. The diagram here is a simple one culled from a 3-speed automatic from the ’60s. The newer systems are however much more complex and are combined with computerized electrical units and components. Transmission fluid serves a number of purposes including: gear shift control, general lubrication and transmission cooling. quite Unlike the engine, which uses oil predominantly for lubrication, every aspect of a transmission’s functions are dependent on a constant supply of fluid under pressure. This is not far from the human circulatory system (the fluid is even red) where even a few minutes of operation when there is a lack of pressure can be harmful or even fatal to the life of the transmission. In order to keep the transmission at optimum operating temperature, a portion of the fluid is passed through one of two steel tubes to a special chamber that is submerged in anti-freeze in the radiator. Fluid passing through this chamber is cooled and then rerouted to the transmission through the other steel tube. A typical transmission system has an average of ten quarts of fluid between the transmission, torque converter, and cooler tank. In fact, most of the components of a transmission are constantly submerged in fluid including the clutch packs and bands. The friction surfaces on these parts are designed to operate properly only when they are submerged in oil and or lubricant.
SEE ALSO:HOW TO ADJUST A HYDRAULIC CLUTCH