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Automatic gearboxes are integral elements of any automatic transmission system. Automatic transmissions have become more and more common due to their ease of use. Several major types of automatic gearboxes are in wide use today, all of which achieve the same goal---switching gears automatically---but do it in different ways. If you are interested in transmissions and the way they work, this is an excellent place to start.

Torque Converters

Torque converter automatic gearboxes are the oldest type of automatic gearbox. They are very easy to use and allow for a smooth ride but are also not very fuel efficient. However, they are extremely reliable. Torque converter automatic gearboxes can be designed to have any amount of gears, and the more gears that are built into one, the more efficient the gearbox. These gearboxes are powered by the turning of a shaft, which connects the engine to the transporter.

Continuously Variable Transmission

Continuously variable transmission (CVT) automatic gearboxes are used only by a few auto manufacturers, including Honda, Nissan, Audi and Mercedes. In addition, CVTs are also usually used only in smaller vehicles. They tend to be more reliable and fuel efficient than torque converter automatic gearboxes. They always come with seven speeds.

Direct Shifts

Direct shift automatic transmissions were created by the Volkswagen Audi Group, and they appear in cars made by this manufacturer, such as Volkswagen, Audi, Skoda and Seat. They come with six speeds, and they are known for their fast shifting ability as well as their fuel efficiency.

Automatic Manual Transmissions

Automated manual transmission, or AMT, gearboxes consist of a strange hybrid of manual and automatic transmission types. They essentially consist of a manual-style gearbox that is nevertheless operated automatically by the vehicles onboard computer. Often, you can choose between either a fully automatic mode or a manual mode. Since a computer switches the gears, AMTs have much lower levels of gear wear as well as increased fuel economy.

Front- and Rear-Wheel Drives

Types of automatic gearboxes can also be differentiated by their location in the vehicle. Front-wheel drive automatic transmission gearboxes are positioned in the front of the car and tend to be smaller and more compact. They are mounted in the engine compartment and are sometimes erred to as "transaxle." Rear-wheel drive automatic gearboxes are situated near the back wheels and tend to take up more space.

An automatic transmission is a complex piece of machinery with many small disks (clutches and steels) contained in larger cylinders forming clutch packs. The transmission uses both hydraulic fluid and electronics to control these clutch packs. When an automatic transmission goes bad, it doesnt need to be replaced---instead, it can be rebuilt. This rebuilding process requires some common tools and a few more-specific tools that the average mechanic may not have.

Ratchet Set

The ratchet is a common tool that nearly every mechanic has. This device, used in conjunction with a socket to remove nuts and bolts, is a long metal rod with a ratcheting head to hold the socket. The ratcheting head functions so that the mechanic can reset the wrench without having to remove the tool from the nut or bolt.

Socket Set

The socket is placed on the end of the ratchet and fits a nut or bolt. Sockets are small, cylindrical metal pieces that are hollow inside to allow a nut or bolt to be inserted. They come in many different sizes to fit the variety of bolt and nut sizes available.

Torque Wrench

A torque wrench is similar to a ratchet but is used only to tighten bolts. The other main difference is that it has an adjustable dial to select the proper torque amount for the particular bolt youre tightening; the wrench will emit an audible sound, typically a click, when it reaches the set torque value. This feature assures that bolts are not over- or under-torque, which is especially important when rebuilding a transmission.

Snap-Ring Pliers

Snap-ring pliers are a set of pliers that are used for opening instead of closing. The pliers have small pins on the ends that are inserted into the holes on a snap ring; the device is then opened to free the snap ring from the groove it sits in. This procedure is required when youre rebuilding a transmission, as the clutch packs are held together by these snap rings.

O-Ring Hook

The O-ring hook is a metal hook designed to pull an O-ring from the groove it sits in. An O-ring is a small rubber gasket thats in an "O" shape to create a seal. This is a must in all transmission rebuilds, as there are as many as 10 O-rings to be replaced in a rebuild.

Washer

A washer is between 3 to 5 feet tall and about 3 feet wide, depending on the model. It has a metal door on the front to place parts in for cleaning. Cleaning the transmission case and all of the reused hard parts is a requirement, as transmission failure may lead to metal shavings being spread throughout the internals of a transmission; failure to clean out these shavings can lead to transmission failure after the rebuild is completed. This washing ensures that all of the debris is cleaned out; it also makes all of the parts look new again.

Rebuilding Bench

The bench used is nearly as important as the tools used to disassemble the transmission. This type of bench has a slight slope so that all of the transmission fluid runs away from the mechanic and into a trough for proper disposal. This bench has different slots for all of the common tools used during a rebuild, including hooks so that the mechanic can hang small parts for reuse, as well as straps to hold the transmission in place during the rebuild.

Transmission Jack

The transmission jack is used to lower the transmission during removal and to lift it to reinstall it. This jack is about 3 feet tall and has a plate on top for the transmission to sit on and a series of ratcheting straps to secure the transmission.