Hydraulic Fluid Provides Transmission Power

• A hydraulic transmission in a car is simply a transmission that uses fluid (automatic transmission fluid) under pressure to perform basic transmission functions. Unlike a manual transmission, which utilizes mechanical means to operate the transmission, a hydraulic transmission uses fluid to provide the force, or action, required to shift gears, maintain gear selection, etc. Automatic transmission fluid (ATF) is the lifeblood of a hydraulic, or automatic, transmission. ATF fluid takes the place of mechanical rods, levers and cables that provide the operational force for manual transmission operation.
  
  

Torque Converter Pressurizes Hydraulic Fluid

• A critical component of hydraulic transmission operation is the torque converter, which is a high-powered pump responsible for pressurizing and propelling automatic transmission fluid throughout the entire transmission. For automatic transmission fluid to have the necessary force to engage and facilitate the many facets of hydraulic transmission operation, it has to be highly pressurized; the force and action required to shift the transmission gears and to engage and disengage a transmission is immense. A transmission torque converter supplies this force. A torque converter, which is attached directly to the rear of a transmission, between the transmission and the engine, is comprised of an inner pump, a rotor and a series of fan blades that spin and rotate. The spinning action of these components pressurizes automatic transmission fluid and propels it with great force throughout a hydraulic transmission.
  
  

Pressurized ATF Fluid Performs Basic Transmission Functions

• As pressurized automatic transmission fluid (ATF) circulates throughout a hydraulic transmission, it provides the necessary push and strength to operate various transmission functions. Gear changes, transmission engagement and disengagement, downshifting--these are many of the functions that pressurized ATF fluid makes possible. Circulating ATF fluid is in constant motion throughout a hydraulic transmission; constantly flowing back to the torque converter via transmission lines where it is continually being pumped and pressurized and sent back into action throughout the transmission.