How Does an Automatic Car Transmission Circulate Fluid?by Brendan Malloney
Transmission fluid maintains proper engine performance while keeping transmission components cool and lubricated among other responsibilities. Significant engine damage can result from insufficient transmission fluid levels or fluid pressure in the system.
After starting the engine, hydraulic fluid is sent through all elements of the transmission under pressure especially the torque converter, pressure regulator and valve body. Torque converters immediately convert engine power to the drive train while the valve body shifts engine gears in automatic transmissions and must be properly lubricated while the valve body shifts.
The transmission oil pump pressurizes transmission fluid to circulate throughout the system and its components when the engine is operating. Once transmission fluid returns to the collector tank it passes through a filter, then is pumped back through the transmission.
To maintain stable engine temperatures, transmission fluid passes through a heat exchanger utilizing engine antifreeze in some fashion, depending on engine design. Typical designs draw transmission fluid from the transmission and route fluid into the radiator or the coolant overflow tanks through steel tubing.
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