Automatic transmission clutches (friction discs). Automatic transmission: the device

In recent years, more and more drivers prefer the automatic transmission. And for good reason. This box is more convenient to use, does not require frequent repairs with timely maintenance. The device of the automatic transmission assumes the existence of a number of components and mechanisms. Some of these are friction discs of the automatic transmission. This is an important detail in the structure of the automatic transmission. Well, let's look at what the clutches of automatic transmissions and how they work.

Characteristics

Also, this mechanism is called the friction discs. The detail is a element of the clutch between gears. At a certain point with oil they clamp down and stop the necessary gear. After switching on the transmission they again closed. The mechanism consists of several parts. What – will be discussed below.

Device

The Examining device of a mechanism such as a clutch pack automatic transmission, it is necessary to allocate two main components of the node:

• The Metal part. She is constantly in the grip with housing of the automatic transmission. The metal part of the clutch almost motionless in the box.
• Soft. It rotates with a sun gear of the transmission. Previously soft clutch automatic transmission were made from pressed cardboard. Modern boxes are completed mechanisms with graphite coating. They can withstand higher loads.

By the Way, in the 90-ies of the clutch pack were one-sided, with no overlap. The design used separate paper and metal disks. Now they have a graphite coating, even on the steel elements. Clutches of the automatic transmission is soaked with oil, thereby protected from friction and overheating. Typically, the package consists of two CD sets. First is metal, then – soft. Both alternate with each other.

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About the friction plate

This element is cellulose-based. Pad disks impregnated with special resins. This is necessary in order to drive had a good engage and not slip in the torque transmission. Since the mechanism is subjected to constant loads at its perimeter you can see the notches spiral shape. They are installed in the direction of movement of the discs. Thanks to them, significantly reduces the temperature of the friction which arose from the friction.

Note that the smaller the depth of notches, the higher the risk of combustion of the disk. Oil cannot pass through the groove in the right amount. As a result, the temperature reaches 400 degrees Celsius and above. By the way, the pad can be made not only on graphite, but on a Kevlar based. It is less prone to wear. The producers themselves do not reveal the full composition of the material Kevlar lining.

Depending on the design of the element can be of different types. There are monolithic lining with split channels to drain the oil and the elements, consisting of individual segments. In the latter case, the segments are separated by seams until the adhesive layer. These pads are used only on expensive cars. Segment elements have a complex production technology. Pads have good heat dissipating qualities. This characterization is achieved through the depth maloothodnyh channels.

Adhesive for clutch

To be applied to the surface of the disc, this grip uses a special lacquer coating. It includes resinous compounds having a high melting point. The pad is placed on a metal surface of the disk and glued by pressing.

Working Principle

The Clutch of the automatic transmission are responsible for the same function as the clutch on the mechanical box. The elements are mounted on the sun gear, each of which is responsible for a specific transmission. They are placed in the overall design. The number of packets of the clutch can be from two (in the most simple 4-step “machines”) to four (for modern 6-speed automatic transmission).

So, let's look at how this mechanism works. In the mode “neutral” clutches automatic transmission spin freely from each other. They are soaked in butter, but do not work under pressure. After the driver moved the gearshift lever in position “drive”, the pump pressure increases. The oil in the box passes to a special channel through the hydraulic unit.

As a result of friction discs pressed against each other under pressure. Activated the desired gear of the planetary gear. The car starts moving. The wheel speed depends on selected gear in gearbox (in other words, from the transfer on the box).

Requirements

Friction linings automatic transmission must meet the following requirements:

• Durable.
• High thermal conductivity (should absorb the oil).
• Heat Resistance (high-quality clutches can operate in temperatures up to 200 degrees Celsius without change of properties and characteristics).
• Dynamic quality. Disc set should transmit torque modulated slippage.
• Static quality (high threshold slippage of the clutch).

About the online

How can be the packageclutch? The resource disk is large enough. Since they are in oil, it is subjected to minimum wear. When the timely replacement of transmission fluid resource of the clutch will be 200-350 thousand kilometers. Experts focus on the regulation of oil replacement in automatic transmission. After all, if you ignore the timing, the grease will quickly lose their properties.

As a result, the elements of the automatic transmission (including the clutch) will work in the regime of high loads. Their life is reduced in 3-5 times. Therefore it is so important to change the transmission oil. On automatic transmissions this time limit is 60 thousand kilometers (not applicable to transmissions with dry clutch). Made with both full and partial replacement. Experts recommend using the first option. When the temperature starts to go down the strip? The critical values for it – 140-150 degrees. Yes, the material can withstand 300 degrees, but only a fraction of a second. Further, the paper starts to crumble and burn. By the way, suffers not only overlay, but also hard disks.

Renovation

Is it Possible to restore such transmission, as the automatic transmission? Repair clutches involves complete replacement of the disc set. To restore them, it makes no sense (the same as to repair brake pads). What the clutch of the automatic transmission cost? The cost of the new package begins from 8 thousand roubles, and it without works. Services such as the replacement of clutches of the automatic transmission, is in Moscow of 10 thousand rubles. And change they are not separately and assembled, the whole package. Knowing the cost of the work, you will understand why it is so important to change the transmission fluid. ATF-oil, though much more expensive than regular, but this price does not compare to the repair of the burned-down box. If the time served by an automatic repair it will need over two hundred thousand kilometers.

Conclusion

So we found that are friction discs of the automatic transmission. As you can see, this mechanism performs is not the last function in the work of the mechanical box. And in order to protect it from wear and tear, it is recommended to follow the rules of oil changes. Dirty grease – the main enemy of the friction discs. Also note that this clogged not only the filter but also the radiator. In the result box constantly
Subjected to overheating.