An automatic transmission has a heart of sorts. It is called a pump. There are several styles of pumps that we will get into in a few minutes. The pump in an Automatic transmission pumps the oil through out the transmission in order to make pressure, which we call hydraulic pressure. The fluid flows through a maze of passage ways, tubes, clutch packs, planetary gears, etc., (I could go on and on).., in a similar manner to the way blood flows through your brain, veins and arteries and internal organs. It is really cool.
The two most common pumps that are used almost exclusively are a gear drive pump, and a vane and rotor pump. Both pumps have the same duties which is to make a lot of pressure and send it to the correct places allowing the tranmsisson to perform all of it’s functions. The duties include pushing clutch pistons together, applying bands, lubrication and much more. FYI, A substancial loss of transmission fluid will ruin or “kill” a tranmsission, much like massive loss of blood will kill a human.
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- gear-pump
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- Vane and rotor pump
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- Rotor
It is easy to see the differences in styles. Although one type of automatic transmission pump is no better than the other type, the point is that they make as much as 300 PSI (pounds per square inch) of pressure, which is why I want to mention the pump assembly produces uncontrolled pressure, so a PR (pressure regulator valve) is the first control the fluid passes through so the fluid pressure is being controlled properly for each function. Simple, eh?
We hope to cover every component in your transmission and make it all sensible to you. If you don’t understand please let me know in the comment area so I can do a better job of putting it in terms you will understand. In the 25 years I owned my transmission shop (I sold it three years ago) the more my customers were educated about an automatic transmission the better decision was made too. An educated consumer is more likely to develop the right strategy and get the proper product.
Make sure you read how to maintain your transmiission so you don’t have a premature tranmsission failure, your transmissions pump is a precisely built piece of equipment that needs to be lubricated, and fresh fluid works better than old fluid. I can’t stress enough using my personal guidelines for a long transmission life.
Generally speaking when a transmission pump fails, you probably will need a new, rebuilt or used transmission. When a transmission has no pressure, none of the internal components can be activated since they operate off of fluid pressure. The same thing with massive fluid loss, when there is nothing to make pressure with, you have a no go situation. GotTransmissions .com is one of the most respected transmission supply companies in the world. Give them a call at 1-888-344-8044.
Remember, I will cover more of the parts and functions in future articles here at GotTransmissions.com Blog with the hope you will have a general idea of how an automatic transmission works. Please feel free to ask a question through our comment area or simply make a comment.
My muffler bearing is making noise it must have seized because now i have more power.
I have just had a replacement CVT gearbox fitted in my 1995 Volvo 460SI. It runs ok when it has been running awhile. Gear selection, kickdown seem to work fine. Oil level is ok. The problem is starting. When put into gear, there seems to be no preesure build up in the box to make the car creep forward. I have to greatly increase the revs to get the car to move. Is this likely to be a pump problem or can it be something else?
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