One Valve, Two Valve, Three Valve, Four….

Welcome back! This week we are going to see what exactly the Valve Body is and the purpose it 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 drilled a well and learned all about Texas Tea and just how important Oil is to your car’s transmission. You can do a re-read of it here. Or, keep reading for the quick recap.

Oil and the pump it goes through creates the pressure necessary for your transmission to function…period. It is this pressure that keeps the transmission fluid flowing throughout your car’s system, which, in turn, keeps it cool, changes gears and lubricates just about everything else and keeps parts moving. Let’s face it – we like moving parts.

We’ve added a few words this week: Pipe, Valve, Servo, Servomechanism, Servomotor, Solenoid, and Throttle. 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.

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.

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.

Pipe – A long tube of clay, concrete, metal, wood, etc., for conveying water, gas, oil, etc. or for use in construction. Also, anything tubular in form.

Valve – Any device in a pipe or tube that permits a flow in one direction only, or regulates the flow of whatever is in the pipe, by means of a flap, lid, plug, etc. acting to open or block passage.

Servo – This is short for Servomechanism OR Servomotor.

Servomechanism – An automatic control system in which the output is constantly or intermittently compared with the input through feedback so that the error or difference between the two quantities can be used to bring about the desired amount of control.

Servomotor – A device, as an electric motor, hydraulic piston, etc., that is controlled by an amplified signal from a command device of low power, as in a servomechanism.

Solenoid – A coil of wire, usually wound in the form of a helix, that acts like a bar magnet when carrying a current: used in brakes, switches, relays, etc..

Throttle – The valve that regulates the amount of fuel vapor entering an internal-combustion engine or controls the flow of steam in a steam line. This is also known as the Throttle Valve.

Come in Houston! Do you read me??

Last week we talked about how the transmission fluid is the ‘blood’ that flows through your car. And, that it is the oil that creates the ‘blood pressure’ of the system. Using this same type of analogy, the Valve Body is the ‘brain’ of your vehicle. This is where everything is controlled. We touched briefly on the Valve Body and its purpose a while ago here.

 

A Valve Body

A Valve Body

 

In a nutshell, the whole purpose of the Valve Body is to smoothly shift gears as you are driving down the road. That is all. The Valve Body is an intricate & specialized maze of channels that directs the transmission fluid that activate whatever gears are needed to shift to.

For example, if the car needs to shift from second to third gear, the transmission fluid needs to flow through the channels to the specific valve that is for that function. This valve is often called the 2-3 valve. And oddly enough, there is a specific valve for shifting from third back to second and it’s commonly called the 3-2 valve. In this system, there is a valve for everything!

 

Simple Gear Shift Stick

Simple Gear Shift Stick

 

The most important valve is the Manual Valve. THIS is the valve that you actually have direct control over and basically gets the whole process going. The Manual Valve is the one that is directly connected to your gear shift. In an automatic transmission, the second you move the gear shift into the Drive position, the Manual Valve directs the transmission fluid to the clutch packs that activate 1st Gear. At the same time, it engages the monitoring of your vehicle’s speed and throttle position to best determine the correct time and force needed to do the shift from 1st Gear into 2nd Gear.

Most automatic transmissions nowadays are computer controlled with electrical solenoids mounted in the Valve Body to help with the direction of fluid to the appropriate clutch packs, bands or servos. This is done to make your car more efficient and to be more precise in determining shift points while you are moving.

My Sole….what??

It’s a Solenoid Pack. To further simplify the definition we listed above – It is simply a coiled wire that acts like a magnet when an electrical current is running through it. By acting like a magnet, it can easily open and close valves.

Now, 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’ its working), engine speed, vehicle speed and many more. By compiling all of 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.

For Next Week

This week we’ve touched on how a computer controlled transmission works by interacting with sensors and solenoid packs. Next week, let’s go old school and take a look at how non-computerized transmissions work and what parts they have that differ from the computerized ones.

Until Next Time….

 Anthony’s Automotive

Under Pressure

Welcome back to our blog! This week we are going to jump right into the rather complex and winding part of the automatic transmission– the Hydraulic System. But before that, like always, time for a quick recap & review some definitions.

 

Previously on Anthony’s Automotive Blog….

 

Last week, we learned all about the One Way Clutch (also known as the Sprag Clutch) and how it will allow movement in one direction but not in the opposite direction. You can do a re-read of it here.

For ease of understanding, the One Way Clutch works very similar to how a bicycle works in that when you move the pedal in a forward motion, it moves the bike wheels. But, on most bicycles, if you try to move it backwards, the wheels won’t move at all. In fact, engaging the One Way Clutch puts you in a “coasting” mode – the engine is still running but no gears are activated and the wheels are kind of moving from the energy already generated from the engine.

 

There are a couple of new words added to our vocabulary this week. 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.

Gear – One of a set of toothed wheels that work together to alter the relation between the speed of a driving mechanism (such as the engine of a vehicle or the crank of a bicycle) and the speed of the driven parts (the wheels).

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..

Fin – (this one is a little tricky) Anything like a fin in shape or use; specifically, any narrow edge or ridge formed in manufacturing, as on a casting by metal forced through the halves of the mold; and/or any fixed or movable airfoil whose chief function is to give stability in flight.

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..

 

Can you feel the pressure….

 

The Hydraulic System in an automatic transmission is a complex labyrinth of passages and tubes. The whole purpose of this system is to send transmission fluid under pressure to all parts of the transmission and torque converter.  I have included three different examples of what a Hydraulic System can look like. You can try this yourself by searching for “automatic transmission hydraulic system” and see all the different diagrams that you can find. Long story short – there is a lot to choose from and they are all beyond complex.

 

 

Transmission fluid serves many purposes in this system. It is involved in the shift control process. It is used for general lubrication of the system. And part of it connects up to the radiator so that means it assists with keeping your transmission cool.  All of these aspects of a transmission’s functions are dependent on a constant supply of the transmission fluid under pressure.  You can think of the transmission fluid as being the blood of your car. In fact, it’s even red in color.

 

And just like your body, it is vastly important that this fluid is always under pressure. Any lack of pressure at any time can be harmful or even fatal to the life of your transmission. In fact, most of the problems that come from your transmission has to do with a lack of fluid or a lack of pressure. It simply does not work right without either.

 

And exactly how much fluid are we talking about here? Your typical transmission has an average of 10 quarts of transmission fluid that runs between the transmission, the torque converter and the cooler tank. That is 2.5 gallons of fluid! In fact, most of the components of the transmission are constantly submerged in this fluid. And this includes the clutch packs and bands. In fact, the friction surfaces of these parts are designed to operate properly only when they are submerged.

A Gallon Jug

As I mentioned earlier about keeping your transmission cool, a portion of the transmission fluid is sent through one of two steel tubes to a special chamber that is submerged in the combination of antifreeze and water that is in your radiator. The fluid that passes through this section is cooled and then returned to the transmission through the other steel tube.

 

For Next Week

Let’s continue examining the Hydraulic System of the Automatic Transmission and find out how the Oil Pump factors into this system.

 

 

Until Next Time….

 

Anthony’s Automotive