AUTOMATIC TRANSMISSION: Now let's discuss an automatic transmission. As we can see here in the illustration, the power in the engine is made by a series of explosions in the cylinders which turn the crank shaft and make spinning power at the flex plate. The torque converter which connects to the flex plate, takes this spinning power and utilizes three converters or fans to stir up the transmission fluid and develop hydraulic pressure inside the transmission, so that the gears can be changed. When engine speed is low, only the impeller fan which is driven by the spinning flex plate and the turban fan which drives the input shaft, are used. Hydraulic pressure is, therefore, low and only the lower gears are utilized. When engine speed increases, the stator fan begins to turn thus increasing hydraulic pressure and forcing the higher gears into play. The gears are pulled in and out of action by the valve body, bans and clutch plates which react to the amount of hydraulic pressure in use. The oil pump in the transmission pulls the transmission fluid from the transmission pan and forces it to the torque converter where it is kept under constant pressure. The oil pump on most transmission also circulates the transmission fluid from the torque converter via a coolant line to a small radiator inside one tank of the engine's radiator to be cooled. Another line returns the cooled fluid to the body of the transmission where it passes the band, clutches and valve body before returning to the transmission pan. From the output shaft in the transmission, the power which is now geared to the relevant speed, travels down the drive shaft to the differential. The differential, making use of its pinion, ring and side gears, takes this power and reduces it to the proper gear ratio before turning it 90 degrees and sending it, via the rear axle shaft, to the rear wheels. It also allows one wheel to turn faster than the other so that the car can corner smoothly. Automatic transmission maintenance involves checking the fluid level, having your auto mechanic replace the fluid and the filter at specified intervals and checking for leaks. Check your automatic transmission fluid with the car running at idle and in park. Remove the dip stick and make sure that it is full, that the fluid is red and doesn't smell burnt. If it smells burnt, it's time to replace. If it's not full, it's time to add. The automatic transmission requires very little maintenance except for the fluid and filter change. The fluid and filter change is affected on the under side of the transmission. Change your automatic transmission fluid and filter with the engine warmed, turned off and the car raised. Once this is done, you'll need to loosen all the pan bolts. Next, remove them all except for two opposing bolts. Then, while supporting the pan with one hand, remove the final two bolts with the other. Insert a wooden scraper between block and pan gasket and carefully remove the fluid filled pan. Strip the old gasket from the pan, empty and scrape the pan with a scouring pad and rinse with solvent. Remove the old filter and replace it with the new filter making sure it's in the exact same position as the old one. Next, apply gasket seals to pan and attach the new gasket to the pan. Re-attach the pan to the block by finger tightening first the opposing two bolts to hold the pan in place. Finger tighten remaining bolts and then carefully tighten all the bolts in a sequential opposing manner being careful not to over tighten. Replace the transmission fluid at the dip stick utilizing a clean funnel with the proper amount and type for your car. Check dip stick after adding each quart until you get a full reading then start the car and again check the level and add if needed being careful not to over fill. Also, check for leaks at the transmission pan and tighten bolts if leaks are found remember not to over tighten.
