Welcome back! I know last time we said that we’d look at how the non-computerized transmissions work but we’re going to hold off on that. Instead, let’s review all that we have learned over the past several weeks. We want to make sure you have a good understanding of how the transmission works before we add any new data and concepts to this.
The Automatic Transmission
In this photo, you will see exactly what we’ve been talking about for the past several weeks. This is the side view of your car’s transmission. You can even see the Gear Shift attached. This photo gives a great perspective on how the transmission looks and where everything is placed in relation to each other.
Now…how does it work again?
You put your key in the ignition and you turn your car on. The engine is now running and the Torque Converter has been engaged. Transmission fluid is now pumping through your car’s transmission via the Pump, through the Turbine, into the Stator and into the One Way Clutch. This essentially keeps your engine running and keeps your car moving while its shifting gears, idling, etc..
When you shifted your Gear Shift into the Drive position, you have basically put it into First Gear and told your car that you want all the gears available for it to use while you are moving forward.
Now back to the One Way Clutch – the transmission fluid doesn’t just stop there. It keeps moving. Through a complex series of passages and tubes, the fluid moves into the Valve Body of your car’s transmission. And it does this only because it is under pressure the entire time.
This pressure is generated by the Oil Pump when you turn your engine on. It is connected to the torque converter which means it is connected to both the engine and the transmission. As long as there is sufficient oil located in the oil pan (on the bottom side of the transmission), it will create pressure and will allow the transmission fluid to flow through the transmission.
Now back to the Valve Body – transmission fluid is directed to the channels that lead to specific valves required to allow a gear shift to occur.
And how exactly does it know which channels to use?
In a computer controlled transmission, there are sensors that are used to capture lots of data related to your engine: brake pedal position, engine load (how ‘hard’ it’s working), engine speed, vehicle speed and many more. By compiling all this information, it can exactly pinpoint when a gear shift needs to occur. AND when it has properly identified that moment, it transmits to the Solenoid Packs in the transmission so that they can redirect the transmission fluid as needed to the correct clutch pack/band/servo to shift the gear.
Remember – a Solenoid Pack is simply a coiled wire that acts like a magnet when an electrical current is running through it and it can easily open and close valves.
In a Nutshell
You turn your car on. This causes the oil to create pressure that allows the transmission fluid to flow through the valve body, which selects the optimum gear for your car to be in at that specific moment. All you do is turn the car on, tell your car you want ALL the gears (putting in Drive) and put your foot on the gas pedal.
Until Next Time….
Welcome back! This week we are going to see what role the Oil Pump plays in your automatic transmission. But before we get into that, like always, time for a quick recap & review some definitions.
Previously on Anthony’s Automotive Blog….
Last week, we learned all about the wonderful, complex part called the Hydraulic System. You can do a re-read of it here. Or, keep reading for the quick recap.
The Hydraulic System is what keeps the transmission fluid under pressure and sends it to all parts of the transmission and torque converter. It is essentially the blood system of your car. Even the transmission fluid itself is red in color, just like your blood. And it is most important that it remain under pressure at all times.
We’ve added a couple of words this week: Oil, Soluble, Solvent, Flange, and Regulator. You can find them at the bottom of the list. As always, you can find our entire and current automotive dictionary here. Feel free to save its link so that you can find it again in case we use a word that happens to not be on this week’s list.
Our Growing Automotive Vocabulary
Here are the related words for this week’s topic. Enjoy expanding your vocabulary.
Transmission – The mechanism by which power is transmitted from an engine to the wheels of a motor vehicle.
Torque Converter – A device that transmits or multiplies torque generated by an engine.
Automatic – A device or process that works by itself with little or no direct human control.
Automatic Transmission – An automotive transmission that can automatically change gears as the vehicle moves, freeing the driver from having to shift gears manually.
Clutch – A mechanism for connecting and disconnecting a vehicle engine from its transmission system.
Band – Something that binds, ties together, restrains, etc.; a strip or ring of wood, metal, rubber, etc. fastened around something to bind or tie it together.
Pump – Any of the various machines that force a liquid or gas into or through, or draw it out of, something, as by suction or pressure.
Sprag – A device for preventing a vehicle from rolling backward on a grade.
Radiator – A device of tubes and fins, as in an automobile, through which circulating water passes to radiate superfluous heat and thus cool the engine.
Tube – A hollow cylinder or pipe of metal, glass, rubber, tec., usually long in proportion to its diameter, used for conveying fluids, etc..
Hydraulic – Operated by the movement and force of liquid; specifically, operated by the pressure created when a liquid is forced through an aperture, tube, etc..
Oil – Any of various kinds of greasy, combustible substances obtained from animal, vegetable, and mineral sources; oils are liquid at ordinary temperatures and soluble in certain organic solvents, as ether, but not in water.
Soluble – That can be dissolved; able to pass into solution.
Solvent – A substance, usually liquid, that dissolves or can dissolve another substance.
Flange – A projecting rim or collar on a wheel, pipe, rail, etc,. to hold it in place, give it strength, guide it, or attach it to something else.
Regulator – A mechanism for controlling or governing the movement of machinery, the flow of liquids, gases, electricity, steam, etc..
Black Gold…Texas Tea…
The Oil Pump in your transmission is what produces all the oil pressure necessary for your car’s transmission to function. Please note that this is a separate pump from the pump that we talked about earlier in the torque converter (please recap here to clear up any confusion you may have). When you talk about getting the oil changed on your car or checking the oil on your car, THIS is the part we are talking. It works hand in hand with your car’s transmission.
Like I mentioned above in the recap and in last week’s post, pressure is one of the most important aspects of your transmission and its ability to operate. Yes, it does need to have transmission fluid to function. BUT that fluid absolutely must be under pressure at all times. It is the Oil Pump that creates this pressure.
The Oil Pump itself is located at the front of the transmission case. It is also connected to a flange that is on the torque converter housing. This makes the pump connected directly to both the transmission and your engine (through the torque converter.)
Because the torque converter is connected to the engine, the Oil Pump will produce pressure automatically while the engine is running and if there is transmission fluid available. This is why it is also important to have your transmission fluids checked regularly for optimum volume. The Oil Pump will not be able to produce pressure without a sufficient amount of transmission fluid located in your transmission system. Just as in the human body, if you don’t have enough blood pumping through your veins, you won’t function as well. And like I mentioned before, the transmission fluid in your car is the blood of your car.
The oil is located in the oil pan that is typically located on the bottom side of your transmission. The oil, itself, enters the pump through a filter (yes THAT filter that you need to have checked and changed during regular maintenance.) The filter is at the bottom of the oil pan and has a tube running from it to the oil pump. This is how the oil gets to the pump. From the pump, where it is now under pressure, it is then sent to the Pressure Regulator, the Valve Body (see next week) and other parts beyond.
So the bottom line is (and bringing together what we learned last week and this), you need to have a good level of transmission fluid in your transmission AND you need to have a good level of oil in your oil pan so that it can create pressure which, in turn, allows your transmission fluid to be transmitted to other areas of your car to either keep it cool, shift gears and keep other parts lubricated and moving.
For Next Week
It’s time to crack open the skull and look at the brain of the Automatic Transmission – the Valve Body.
Until Next Time….