Disc brakes: main characteristics, advantages and features. Spare parts for special equipment - winch brake friction discs What a brake friction disc looks like under a microscope

Clutches (friction discs, clutch packs) - clutch elements between gears in, necessary to turn on and. The clutch consists of a base (steel disc). A special friction lining is glued to the specified disk.

The main task of the clutches is to close (compress) and open (unclench) at a strictly defined moment, due to which the desired gear, which corresponds to a particular gear, stops or starts to rotate. The clutches compress and decompress under the pressure of the ATF transmission fluid.

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The device of automatic transmission friction discs and the principle of operation

First of all, there are two types of frictions:

• metal discs with a friction lining, which are engaged with the body of the automatic transmission. Such clutches are immovable.
• soft clutches rotating simultaneously with the sun gears. Such clutches are made of a soft material (for example, pressed cardboard) and have a hardening coating (graphite, etc.)

Different automatic transmissions may have different types of clutches. For example, in automatic transmissions made in the 20th century and which are now obsolete, the friction discs are one-sided, without pads. In fact, this means that there are two discs, one steel and the other cardboard.

More modern types of automatic transmissions have received modified friction discs with adjustments, as a result of which the clutch resource has been increased, heat dissipation has been improved, etc. Friction discs are collected in so-called "packages" (friction package), when one disc is made of metal and the other is made of soft material. These pairs are duplicated several times to form a finished package. For example, a simple 4-speed automatic has 2 or 3 sets of clutches.

If we talk about the principles of operation, you need to understand that the so-called planetary gear is used in the automatic transmission device. So, in a nutshell, when the gear is out, the friction discs rotate without restriction, that is, they are not pinched due to lack of oil pressure.

However, at the moment the gear is engaged, ATF under pressure passes through the channels of the valve body, as a result of which the discs are compressed (the clutches are tightly pressed against each other). As a result, the desired gear is connected, while the remaining gears in the automatic transmission stop.

Clutch service life and major breakdowns

Many motorists are well aware that the most common malfunction of the automatic transmission is the wear of the friction discs (friction wear). At the same time, it is impossible to avoid such wear, however, competent maintenance and operation of the automatic transmission allows you to increase the resource of clutch packs up to 250-400 thousand km. run.

To do this, it is necessary to change the oil in the automatic gearbox in a timely manner (every 40-50 thousand km), monitor the oil level in the gearbox, prevent overheating, do not skid in a car with automatic transmission, etc. If the friction discs are out of order, as a rule, you can hear that the friction clutches have burned out. In practice, this manifests itself in such a way that automatic transmission gears do not turn on, gears slip, etc. Let's figure it out.

So, the friction discs themselves may well serve for a long time (a mileage indicator of about 500 thousand km is quite real), since these discs rotate in oil. So, their resource largely depends on the condition of the oil. If you do not change the oil in the machine and the oil filter, and at the same time subject the transmission to serious loads, it is quite possible that the clutches will also fail by 80-150 thousand km.

The reason is the loss of ATP oil properties and aging, pressure reduction, contamination of the fluid itself with gearbox wear products, problems with valve body channels, solenoids, etc. Together, the oil pressure on the clutches will drop, the compression will not be as effective and the friction discs will slip in this case.

It turns out that they heat up and “burn out” from friction, and the friction packs are destroyed. Often, the smell of burning can also be noticed when analyzing the ATF fluid, when the oil in the automatic transmission box smells burnt precisely because of slipping and burning of the friction clutches.

What is the result

As you can see, the friction discs of an automatic transmission are a kind of clutch in a manual transmission. At the same time, the element is quite reliable, but only if everything is in order with the oil pressure in the “automatic” box and the liquid itself is clean.

A decrease in pressure usually occurs when:

• the oil level (ATF) in the box is not correct;
• the transmission fluid itself has lost its properties and / or is heavily contaminated;
• there were problems with the oil pump, the throughput of the automatic transmission oil filter or oil cooler was reduced;
• valve body channels are clogged, solenoids do not work correctly, etc.

In the presence of such problems, the transmission may switch jerkily,. As a rule, if the problem is not paid attention to, the friction discs are the first to fail, the friction clutches slip and burn. As a result, the ATF oil in the automatic transmission smells burnt, the color of the oil in the automatic transmission changes, etc.

To solve the problem in some cases, it may be enough to flush the oil cooler, change the oil in the automatic box, and also the oil filter. In other situations, it may be necessary to disassemble the automatic transmission to replace the clutch packs, flush the valve body channels, and check the performance of the solenoids.

One way or another, when the first signs of clutch slippage are detected, it is necessary to stop the operation of the vehicle and deliver the car to the service station in order to conduct an in-depth diagnosis of the automatic transmission.

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How automatic transmission works: classic hydromechanical automatic transmission, components, control, mechanical part. Pros, cons of this type of checkpoint.

Disc brakes known for a long time. They have proven themselves well and today are used very widely. But first things first.

Currently, there are two types of brake systems - drum and disc. For the first time, disc-type brakes were used in the late 40s of the XX century, and since the 70s, drum brakes on the front wheels were replaced with disc brakes on all cars.

This article will give a detailed description of disc brakes, their advantage over drum counterparts, as well as a description of the components of this brake system (caliper, brake disc, protective screen). In addition, the advantages and disadvantages of different types of disc brakes are described.

Advantages of disc brakes over drum brakes

The advantages of disc brakes over drum brakes include:

• the braking capacity of disk systems is not reduced due to overheating, as they are better cooled;
• resistance of disc brakes to water and dirt is higher;
• maintenance of brake mechanisms is required much less often;
• The friction surface of disc brakes with the same mass is greater than that of drum brakes.

Rice. 1 Thermal expansion of drum and disc brakes

When heated, the thermal expansion of the brake drum - an increase in the inner diameter - leads to an increase in the stroke of the brake pedal or to deformation of the drum, which can cause a sharp decrease in braking action (Fig. 1). The brake disc, in turn, is a flat part, its thermal expansion occurs towards the friction material, so compression of the disc cannot cause deformation sufficient to affect the braking performance. In addition, centrifugal force throws contaminants away from the brake disc.

Figure 2 shows why a disc brake cools better than a drum brake. Cooling air begins to cool the brake drum only after the heat generated during braking passes through its walls, while the rubbing surfaces of the disc brake are open to air. Heat transfer from the brake disc to the air begins immediately after the brakes are applied.

Rice. 2 Cooling principle for drum and disc brakes

The ability to adjust disc brakes is another advantage. The projection of disc brakes is such that after each application they self-adjust due to the small gap between the pads and the brake disc.

Disc brake device

1 - cylinder block;

2 - brake pads;

3 - clamping lever of the caliper;

4 - protective cover;

5 - axis of the clamping lever;

7 - brake caliper;

8 - brake disc;

9 - fittings for removing air;

10 - brake hoses.

The main parts of disc brakes are caliper, brake disc, pads, protective screen. Let's consider these elements of the braking system in more detail.

Disc brakes are divided into single and multi-disc. The largest and heaviest part of them is the brake disc. The mechanism of operation of single disc brakes is that brake pads with friction material clamp one brake disc during braking. Multi-disc brakes, commonly used in aviation, have several rotating brake discs separated by fixed discs (stators). On the brake shield of multi-disc brakes are hydraulic cylinders and pistons that actuate the brake shoes and, when extended, clamp the brake discs and stators. Multi-disc brakes are made entirely of metal, while single-disc brakes are composed of organic and metallic friction material.

The material of the brake disc, like the brake drum, is usually cast iron. Cast iron has good wear resistance and good frictional properties, has high hardness and strength at high temperatures; it is easily machined and its cost is relatively low.

The size of the brake disc is equal to its outer diameter and the total thickness of the cross section between the two working surfaces. The diameter of a brake disc is usually limited by the size of the wheel, and a ventilated brake disc is always thicker than a solid one. For a disc brake, this is the total area of ​​contact with the two brake pads for one rotation of the disc.

A high coverage area per ton of vehicle in well-designed brakes means that the braking system is highly efficient. The area of ​​coverage of a disc brake is the friction area of ​​the brake pads on both sides of the brake disc. Thus, it is more accurate to use Rp instead of Rr, however, since in most brakes both radii are almost equal, Rr is used for ease of calculation, which is easier to measure.

The brake disc is attached to the spacer, which, in turn, is attached to the wheel hub or axle flange. The spacer provides a longer path for heat transfer from the friction surface of the brakes to the wheel bearings, which allows you to keep their temperature quite low. Production car spacers are usually made of cast iron as a single piece with the brake disc, while racing car spacers are made as a single piece of aluminum alloy. The disadvantage of aluminum alloy spacers is a higher thermal conductivity than cast iron, which leads to greater heating of the wheel bearings.

Ventilated disc brakes

The brake disc can be solid or with ventilation channels inside it. Light vehicles usually use solid brake discs. Ventilated brake discs with radial cooling channels are used on heavy vehicles that require the installation of discs of the largest possible sizes.

Powerful racing cars are equipped with ventilated brake discs, and there may be differences in the thickness of their side walls. In order to maintain the same temperature on each side of the brake disc, on many car brakes the side of the brake disc closest to the wheel is thinner than the opposite side. The wheel resists the passage of cooling air to the outer working surface of the brake disc, which makes it hotter than the inner side, so the large thickness of the poorly cooled outer surface of the brake disc helps equalize their heating temperatures.

Racing brake discs often have curved cooling ducts that improve airflow efficiency. Brake discs for the left and right sides of the car are not interchangeable due to the curvilinearity of the ventilation ducts. A brake disc with curved vents or slanted slots must rotate in a specific direction to work effectively. The correct direction of rotation in relation to the ventilation holes and slots is shown in the diagram.

Typical brake area values ​​are shown in the table for typical 1981/82 vehicles.

Typical brake area per ton of vehicle weight

Powerful cars have higher values ​​of this indicator compared to economical sedans.

Possible problems with disc brake systems

With frequent intensive braking, cracks appear on the ventilated brake discs. The reason for this is thermal stresses and the pressure of brake pads on thin metal walls in each cooling channel. Thermal stresses in a brake disc with a cast or bolted spacer are caused at the junction because the temperature of the brake disc at that location is higher than that of the spacer.

The outer part of the brake disc expands more when heated than a cold spacer. This leads to the fact that the brake disc is deformed and bent, its taper appears, which leads to uneven wear of the brake linings. Constantly repeated, the expansion and contraction of the brake disc causes cracks to appear. The support of each side of the ventilated brake disc and its effective cooling reduce the likelihood of cracking on it.

Brake drums and brake discs are designed to withstand the most severe form of thermal stress with each application of the brakes, but repeated applications of the brakes can cause fatigue cracks. If the brakes are used in hard braking mode, they should be checked more often.

Disc brake calipers

Let's take a closer look at the caliper device. Disc brake calipers include brake pads and hydraulic brake cylinders with pistons that press the pads against the brake disc. The principle of operation of all disc brake calipers is the same: when the driver presses the brake pedal, under the pressure of the brake fluid, the pistons move the brake pads, which clamp the brake disc.

Passenger car calipers are usually made of relatively cheap ductile gray cast iron with spheroidal graphite. However, they are quite heavy. Racing or generally powerful cars are usually equipped with aluminum alloy calipers, their mass is almost half that of cast iron.

Types of calipers, their features

There are two main types of calipers - fixed and floating.

Rice. 4 Differences between different types of calipers

Fixed calipers have more pistons (two or four), are larger and heavier than floating calipers. When working in difficult conditions, they allow more emergency braking before the caliper overheats.

The floating caliper moves in the opposite direction to the piston movement. Because a floating caliper only has a piston on the inside of the brake disc, the entire caliper can move inward to allow the outer brake pad to press against the brake disc. Floating calipers are less likely to leak and wear, as they have fewer moving parts and seals.

Fixed calipers are most often used on racing cars, and floating calipers are most often used on production cars.

Rice. 5 Floating caliper brake disc

The advantage of floating calipers is the ease of application of a mechanical parking brake, since in a design with a single brake cylinder it is easily controlled by a cable, while in fixed calipers with pistons on both sides of the brake disc, this is more difficult. The disadvantage of floating calipers is that they can cause uneven brake pad wear due to movement of the caliper itself.

Possible caliper problems

Rice. 6 Deformation options

• The part of the caliper body that spans the outer diameter of the brake disc is called the bridge. The pressure of the brake fluid causes a force P on each side of the caliper, which tries to bend its bridge. The rigidity of the bridge determines the rigidity of the entire structure of the caliper, since the thickness of the cross section and the mass of the caliper depend on the rigidity of the structure.

• The caliper is located between the outer side of the brake disc and the inner side of the rim, so the space requirements for its placement dictate the design of a caliper with a small cross section. Unfortunately, this can cause it to bend. To improve rigidity, race car brake calipers are designed with wide axles.

• If the brake pad covers the dimensions of the piston, then it will bend when the brakes are applied. To ensure uniform contact between the working surface of the brake pad and the brake disc, several pistons are used.

Rice. 7 Calipers with one and two pistons

• If the caliper mounting device is pliable, then when moving it, twisting may occur, and this, in turn, causes uneven wear of the brake linings, springiness and increases the brake pedal travel.

• Since the brake disc and the caliper bracket are located in different planes, the latter perceives the twisting moment during the application of the brakes. If the bracket is too thin, it will twist, causing the caliper to seize the brake disc. Normally, the thickness of the caliper mounting bracket should be at least 12.7mm.

Features of the operation of disc brake systems

Protective screens are installed to protect the inner working side of the brake disc from dirt and water. Such a device in its design resembles the brake shield of drum brakes. Protective shields resist the passage of cooling air to the brake disc and are therefore not commonly fitted to race car disc brakes.

As for the friction material of disc brakes, it is usually glued to the side surface of brake pads made of steel sheet. Brake pads are sold with brake pads already attached and are not reusable.

The load from the brake pad is usually not applied directly to the piston in the brake caliper. Anti-squeal washers are installed between the piston and the brake pad on many vehicles, designed to reduce the noise that occurs when the pad vibrates or rattles against the brake disc.

Summing up

We examined the design of disc brake systems, features, advantages, strengths and weaknesses of their various types. From the foregoing, it is not difficult to draw conclusions about what should be the most effective braking system for racing cars.

• For racing cars, only ventilated brake discs are suitable, which cool faster. To keep the temperature on each side of the brake disc the same, on many racing brakes the side of the brake disc closest to the wheel is thinner than the opposite side. Curved brake disc vents are more efficient for race cars than straight ones. Directed ventilation channels, compared to the traditional straight design, significantly increase the intensity of air pumping through them, improving heat transfer. The spiral design of the channels more evenly distributes mechanical stresses in the disk, increasing the resource and reducing the likelihood of cracking.

• Perforation of the disc, performing all the same functions of the gas outlet as the grooves, increases the area of ​​the blown surface of the disc, improving cooling. With year-round operation, it improves the cleaning of the disc from moisture and dirt.

• Spacers and disc brake calipers for racing cars are made of aluminum alloy. Lightweight aluminum spacer improves driving performance, reduces thermal stress on the brake disc. The low weight, thanks to the use of aluminum with a low specific gravity, reduces unsprung masses, favorably affecting the quality of the car's suspension.

• Designed for more emergency braking and more flexibility than a floating caliper, the fixed caliper is ideal for racing.

• Sufficient for the operation of racing cars, the rigidity of the brake disc systems is provided by bridges of increased width. Due to the increase and the best distribution of the sections of the "bridge" (an element working on the load expanding the caliper), an increased rigidity of the caliper to working deformations was obtained. Increased rigidity, summed up with a general reduction in operating pressures and reinforced brake hoses, which have a minimal tendency to increase in volume (swell) under load, allows you to get maximum information on the brake pedal and the ability to very accurately dose the braking torque in the system.

• The multi-piston design of the caliper makes it possible to obtain a uniform pressing force of the brake pad to the disc, and the different diameter of the pistons compensates for the difference in temperature conditions of the pad over the contact area, preventing possible uneven wear (tapering) along the front and rear edges. The increased total area of ​​the pistons in the calipers changes the gear ratio of the hydraulic system, resulting in a significant reduction in fluid operating pressures. Low pressures reduce the required maximum brake pedal effort. They reduce the load and harmful deformations on all regular parts of the brake system.

• In the case of using the “floating design” of the disc, recommended for use in extreme load conditions (on the racing track), it allows you to completely remove thermal stresses relative to the central part and prevent the transfer of excess heat to the wheel bearing. Providing normal operation and extended life of these parts in the most severe conditions.

• The larger the diameter of the brake disc, the larger the effective radius of application of the braking torque. This allows you to increase the maximum braking power developed by the system. The effective radius directly affects the coverage area of ​​the working surfaces, which is one of the main indicators of the disk's ability to dissipate thermal energy.

And remember, quality disc brakes are your safety first. Keep this in mind when choosing the right brake system for your car.

The UV31... unified pneumatic clutch-brake is widely used in crank presses and guillotines, as well as other forging and pressing machines for coupling an eccentric shaft with a rotating drive and braking it when performing machine strokes. The UV31... coupling has a reliable, time-tested design, which, with proper operation and timely adjustment, ensures a long service life of the coupling.
However, like any other mechanism, over time, the clutch-brake begins to work inefficiently. As a rule, rubber seals wear out ( pneumatic cuffs), leading And brake discs with friction linings and driven toothed discs. If spare parts are available, the clutch-brake UV31... can be easily restored.
Our company offers the following spare parts: discs with friction linings To pneumatic clutch-brake UV3132, UV3135, UV3138, UV3141, UV3144, UV3146 . Brake discs are laser-cut from steel grade St3 6 mm thick. Deviation from the drawing dimensions is no more than ± 0.1 mm. Brake disc linings are made of a highly wear-resistant friction composite material.
with friction linings are equipped with two hardened steel bushings for connection to the frame or the flywheel of the machine.

UV-3132-00B-009 brake discs (friction) with pads

UV-3132-00B-009 brake discs (friction) with pads

Brake disc with pads for clutch-brake UV3132 Brake discs UV-3132-00B-009 For clutch-brake UV3132 (for presses type KD2120, KD2320, KD2120K, KD2320K, KD2120E, KD2320E , scissors NK3418 etc.) with linings made of friction material are designed to brake the moving parts of presses and shears. Braking is carried out due to the friction force that occurs in the plane of contact (sectors) of the brake discs with the intermediate and pressure discs. brake discs with pads

UV-3135-00B-009 brake discs (friction) with pads

UV-3135-00B-009 brake discs (friction) with pads

Brake disc with pads for clutch-brake UV3135 Brake discs UV-3135-00B-009 For clutch-brake UV3135 (for presses type KD2122, KD2322, KD2122K, KD2322K, KD2122E, KD2322E and other) with linings made of friction material are designed to brake the drive shaft. Braking is implemented due to the friction force that occurs in the plane of contact of the friction linings (sectors) of the brake discs with the intermediate and pressure discs. In our company you can buy brake discs with pads both individually and as a set of three pieces for any type of brake couplings type UV31...

UV-3138-00B-009 brake discs (friction) with pads

UV-3138-00B-009 brake discs (friction) with pads

Brake disc with pads for clutch-brake UV3138 Brake discs UV-3138-00B-009 For clutch-brake UV3138 (for presses type KD2124, KD2324, KD2124K, KD2324K, KD2124E, KD2324E and other forging and pressing equipment) with linings made of friction material are designed to brake the drive shaft. Braking is implemented due to the friction force that occurs in the plane of contact of the friction linings (sectors) of the brake discs with the intermediate and pressure discs. This type of press drive control is called mechanical (or pneumatic, because the clutch-brake is controlled by a pneumatic distributor, usually U71-24A). In our company you can buy brake discs with pads both individually and as a set of three pieces for any type of brake couplings type UV31...

UV-3141-00B-009 brake discs (friction) with pads

UV-3141-00B-009 brake discs (friction) with pads

Brake disc with pads for clutch-brake UV3141 Brake discs UV-3141-00B-009 For brake clutch UV3141 (for presses type KD2126, KD2326, KD2126K, KD2326K, KD2126E, KD2326E In our company you can buy brake discs with pads - ; - ; - ; - ; - ; - .

UV-3144-00B-009 brake discs (friction) with pads

UV-3144-00B-009 brake disc (friction) with pads

Brake disc with slips to the clutch-brake UV3144 Brake discs UV-3144-00B-009 For brake clutch UV3144 (for presses type KD2128, KD2328, KD2128K, KD2328K, KD2128E, KD2328E etc.) with friction linings attached to them are designed to brake the moving parts of the press. Braking is carried out due to the friction force that occurs in the plane of contact of the friction linings (sectors) of the brake discs. In our company you can buy brake discs with pads both individually and as a set of three pieces for any type of brake couplings type UV31..., namely: - brake discs with pads for UV-3132 ; - brake discs with overlays for UV-3135 ; - brake discs with overlays for UV-3138 ; - brake discs with overlays for UV-3141 ; - brake discs with pads for UV-3144 ; - brake discs with pads for UV-3146 .

Regarding the purchase of spare parts for the clutch-brake UV31..., please contact the managers of our company by phone numbers listed in the section Contacts.

Steel discs vice versa: The size is indicated by the inner diameter, the one without teeth, so as not to be confused: measure with a tooth or without a tooth?

When are clutches changed?

Experienced craftsmen first disassemble the box, determine the condition of the friction discs and brake bands, check the gaps in the packages and then order new clutches.

If the clutches of only one clutch pack are worn out, the oil does not smell burnt and the mileage of the car is relatively small for this family, then the master can only replace the worn clutches. Then they order only 3-7 necessary clutches.

The remaining clutches are checked for damage and lining thickness. And if the gaps between the clutches are within tolerance, then such a package can work properly for a long time. ( For the master, it is easier to leave the old friction clutches, which will last for six months. The owner usually waits for very different terms. Worn clutches shift gears with shocks, and as they wear out, with shocks, if the gaps in the packages are larger)

If the clutches of several packages burned out, and with them part of the steel disks ( this is indicated by tint stains on the steel surface), then it is necessary to replace the entire Clutch Kit and brake bands. In many US states, craftsmen are required by state law to replace All frictional discs, brake bands and consumables, if the box came in for overhaul, under the threat of revocation of the license.

Friction linings impregnated with burnt oil absorb oil much worse and poorly remove heat from the surface when touched. And this very soon leads to problems when switching, slippage and combustion of such clutches. Maybe in a few weeks, maybe in a few months.

Clutches burn ahead of schedule (and they are usually designed for the entire life of the transmission) not because they are “weak” or “cheap”, but mainly because. When, due to pressure losses in the line, the pistons do not press the friction clutches to each other. Therefore, to install "reinforced" friction clutches without replacing all the gaskets and rings in the line is to guarantee the rapid combustion of "reinforced" friction clutches.

Another reason to replace all clutches is vibration which have worn the clutch pack unevenly. In this case, it is necessary to change not only all disks (friction and steel) of the packages of this node, but also all neighboring nodes.

Equipment. How many and which clutches are included?

Usually all clutch kits are universal and are assembled by manufacturers so as to fit any automatic transmission indicated in the name of the kit, and of such quality as to work flawlessly for many years.

On the left, the name of the Chrysler Kit says that this kit fits all boxes from A500 to 44RE and all years after 1988.

Friction linings

Friction clutches are selected by manufacturers with a different friction lining, depending on the characteristics of the box and the history of repairs. Some clutches are beige, cellulose, for those packages that mainly work on abrasion. Others are gray or grey-green, for packages that are more likely to slip, overheat and burn out. In the third, they can put the most expensive ones - gray-green with a graphite fiber base. Each material has its own advantages and disadvantages.

The first one has a higher torque transfer threshold, the last one glides better and resists overheating longer. (below)

Friction linings may have slotted grooves for oil movement. (below)

Why do we need clutches, steel discs and brake bands in an automatic transmission?

Clutches work in tandem with steel discs by analogy with the clutch of mechanical gearboxes. Clinging to the steel discs, they connect the two rotating shafts of the automatic transmission. Frictions are assembled in a Drum (which is stillcalled "Clutch Basket") and it has two states: " working" - locked when the clutches are compressed with steel discs through the piston and " free"- when there is a working gap with oil between the clutches and there is no clutch. In the open state, the clutches with steel discs rotate at different speeds.

There are from 3 such drums with frictions in automatic transmissions (plus a brake band) to 7 or more.

The operation of the drums is controlled by a computer by changing the oil pressure supplied by the hydraulic unit / solenoids to the clutch packs., by using - electrovalves hydraulically presses the pistons of the drums, compressing the friction clutches with steel disks of some packages and, relieving pressure in others, allows the springs to open the clutches in non-working packages.

There are drums clutch And braking.

Clutch drum - connects two rotating shafts. Braking drum - closes the drum on the body - slows down one of the elements of the Planet. Previously, the function of braking the planet element to select the desired combination of rotation was performed by brake bands similar to those used for the brake drum rear wheels of cars. ( left)

But now the simple (but cumbersome) design of the tape has almost ceased to be used, replacing the brake bands with friction clutches. braking package.

Unification. For different (in terms of power) transmissions, you can adjust the power of the transmitted torquethe number of clutches and steel discs, fewer clutches for less powerful engines and adding clutches for more powerful ones. And most importantly: - finer regulation of the braking force using .

You can define the difference as follows: Where durability and indestructibility are important and the "high-intelligence" of the box is not necessary, a brake band is used. Clutches are used where you have to compete with DSG and CVT for the approval of fastidious auto-journalists.

Friction classification

Frictions and steel discs are described in the part name, for example:

Friction Disc, TF60SN/09G/09K K3 (C3)- rev, 3rd, 5th (56Tx1.73x157)

description - [ 56Tx1.73x157] - means:

this disk 56T:- 56 teeth, 1,73: - thickness 1.73 mm, and 157 : - outer diameter 157 mm

Applicability - for all automatic transmissions listed in the title,

K3 - the name of the clutch package (K - Kupplung, C - Clutch) or braking (B - Brake) according to the Parts Catalog (European classification).

rev, 3rd, ... - (American classification) the functional purpose of the package: the inclusion of Reverse, 3rd speed ... etc.

What are frictions?

1. In addition to the usual bilateral friction clutches with an internal tooth and steel disks with an external tooth appeared one-sided (combined: steel-friction clutch).

- one-way clutches have a friction lining on one side, and a bare steel surface on the other. Such input shaft clutches may have interior tooth, and the reciprocal one-way clutches (secondary shaft) - outer tooth. In the Part No., they have letters according to the type of tooth: - BI (internal) or -BE (external).

In legendary boxes and Mercedes, for the first time they began to use in large quantities unilateral clutches. Only the French () did it rather to reduce the cost and save money, and the Germans () - with a rise in price, for reasons of compactness, manageability and reliability.

Now there are many boxes (, 722.6, ...), where one-way clutches are introduced into one of the often burning packages as they work more efficiently and are more resistant to combustion.

2. Friction lining material in most caseshas a cellulose base impregnated with special resins to securely grip the steel disc and transmit torque without slipping.

In packs where friction clutches often overheat, friction linings may have notches to drain oil. In the most important packages, the notches have a spiral shape, and are installed strictly in the direction of travel (on the right). The notch here, although significantly reducing the working area, acts as an oil pump gear to increase the speed of oil passage through this channel and better cool the surface. When the depth of the notch is worn, the oil flow decreases, which can lead to overheating and accelerated combustion of the clutches in summer

The friction lining can also be made on a graphite or Kevlar basis. But it must be said that the same Borg Warner, which produces clutches for the conveyor for the same box, simultaneously produces clutches with a cellulose base and without notches, and for other packages - on a Kevlar basis, based on the characteristics of the box in modes. This feature is taken into account in the valve body adjustments.

Manufacturers do not disclose the composition and type of clutch lining material and an order for "Kevlar" clutches cannot be guaranteed. Frictions are supplied from exactly the material that, according to the Manufacturer's calculations, should be used in this package. This applies mainly to machines of the 21st century.

Such friction linings can withstand rather long-term operation at temperatures up to 140º without loss of quality. These materials are more expensive than usual and are found on the market only for individual automatic transmission packages. Their total number does not exceed 3-5% of the total number of friction clutches sold. Such kits have an abbreviation in the name: HEG or " power pack".

It is worth noting that for increased temperature resistance, you have to pay with worse slip characteristics and material stability as it wears..

3. Friction design overlays:

Frictions from individual segments when the segments are separated by seams up to the depth of the adhesive layer

- With monolithic overlay with cut channels for oil drainage. Channels are cut only on friction clutches of packages with an increased risk of combustion. And monolithic without oil channels.

Segmented overlays can be afforded by manufacturers who are willing to invest in sophisticated calculation-cutting-combining-pasting technologies and highly skilled personnel in order to save on overlay material and production conveyor flow.

Friction lining materials are produced by only a few major manufacturers. The type of lining is not essential for the operation of the transmission. The only advantage of segment linings for the owner of an automatic transmission is the number and depth of oil channels.

Friction adhesive

To stick the lining on the surface of the steel disk, a “primer” is first applied - adhesive varnish coating, which usually consists of resins, with a melting point of 180-200º. This melting point (as well as the primer formula) is different for all manufacturers, but it is chosen so high that the adhesive does not melt during the working heating of the oil in the automatic transmission. And so low that it saves money when gluing the overlay at the factory.

Friction n The lining is pressed onto the prepared steel surface by heating in high-frequency currents, melting the applied primer.

This adhesive base is the "main enemy" of the valve body and solenoids.

Why are clutches burning? What happens in the automatic transmission during the operation of burnt clutches?

Friction clutches are theoretically created by designers "eternal" - for the entire service life of the car, but in practice - they often "burn".

Causes of combustion of friction clutches:

Overheating from lack of pressing force and

From a lack of cooling with ATF oil, which removes heat from the surface of the discs.

At the moment of contact between the friction clutch and steel on their surface, the temperature can simultaneously rise to 300-400 degrees. But since the friction linings are impregnated with oil and the very touch in conventional automatic transmissions and "on-off" clutches takes a fraction of a second, the lining does not have time to warm up to critical temperatures. If there is not enough oil or, more often, the clutch is loose, slippage occurs for the "on-off" clutches and they start heat above the flash point of the oil.

When the temperature approaches 140-145º, the cellulose friction lining begins to char, while absorbing less and less oil and cooling worse. Chain reaction.

Heating increases like an avalanche - the adhesive layer melts and becomes glassy and the friction clutch crumbles. At the same time, changes in the metal of the friction clutch and the steel disk occur.In severely neglected cases, not only steel discs burn out from overheating, but also neighboring discs and even the rubber-coated drums themselves (right). This is expressed in the fact that the car "does not pull" at one speed or does not go forward at all.

If the clutches burned out, then most likely the pump in the unit could not cope with the supply of oil to the pistons. Pressure losses usually go through worn, rubber and pistons themselves. Changing clutches and not replacing rings and gaskets is considered a typical mistake and leads to the rapid burning of new clutches.

Persistent(or reference) disk similar to a regular steel disc, but thicker and located at the end of this clutch and disc pack. It is on him that the piston presses (or the retainer rests on the back of the package).

Friction linings differ in functionality:

1. - Thermal conductivity. (ability absorb oil and conduct heat)

2. - Heat resistance (withstand short-term heating (“burns”) when touched up to 300-400 degrees without changing properties)

3. - Stability. (ability to maintain performance during wear and critical condition of the oil throughout its life)

4. - Friction static qualities, (high "slip threshold", the ability to transmit high torque before slipping).

5. - Friction dynamic qualities, (the ability to transmit torque with "modulated slip". Analogy of controlled braking with a brake pedal).

6. - wear resistance, mechanical strength.

There are 2 main groups of frictions:

1. Frictions on-off. They have maximum values ​​in terms of characteristics - 3, 4, 6. Minimum 1, 2, 5.

2. Frictions "slip". For them priority are characteristics 3, 1, 2, 5 .

The reasons for the lack of oil pressure are varied.:

The most common is the ultimate load with cold oil. Most often occurs in winter when leaving a snowdrift or during aggressive cold acceleration.

Pistons. Worn rubber seals, or damaged by chips, or burst along the body - leak oil,

Sealing, adjacent surfaces of the "iron" (drums, calipers ...) are erased, the oil leaves through the cracks and does not reach the pistons.

General lack of oil. Sometimes the pump does not have enough oil due to its low level in the automatic transmission pan, a clogged filter, oil leaks through the seals.

Pump. Often the pump itself, its components, bushings, seals are worn out.

The valve body and solenoids are "eaten" and worn channels "" oil, bursting springs, dirty spool valves that do not open the channel also contribute.

There are many reasons, like links in a long chain. Somewhere, yes it is torn. An autopsy and diagnostics are needed in order to determine the break points of this "hydraulic" chain.

When the piston does not compress the clutches hard enough during acceleration, the clutches slip and do not pull as usual. Which forces the driver to step on the gas to "correct" the slow acceleration. From this, the clutches are even more heavily loaded and heated,which leads to irreversible and catastrophic consequences for the entire transmission.

What is the danger of operating an automatic transmission with worn or burnt clutches?

The article about this is written in more detail.

The first trouble from working with bald clutches is Overheating of adjacent pistons, bushings and a drum. As described above.

The next trouble is that the adhesive layer gets into the oil, with which the lining is attached to the steel base, the oil is contaminated with crumbling fragments of the friction lining. This leads to a chain reaction of problems:

Dirt clogs the valve passages of the valve body with solenoids, which leads to a final pressure drop.

The oil becomes thick and abrasive, worsening the friction of bushings, gaskets and rings, abrading the parts of the automatic transmission hardware, which leads to a rapid decrease in the automatic transmission resource. And thick oil is more difficult to "shovel" the turbines of the torque converter, which reduces power and the engine's energy goes to additional heating of the oil.

The oil abrades the channels of the valve body, which leads to wear and the end of its life.

With a lack of oil, the elements that are close to the axles (that is, the bushings) and the pump sucking oil directly from under its bushing first of all suffer. worn out hanging out the bushings allow the vibrating shaft to break up adjacent friction surfaces. Which leads to accelerated wear of the pump and other hardware.

All this can lead to a car stopping right in the middle of the road.

A new era in the life of "sliding" friction clutches.

Ever since PWM appeared at the end of the 20th century solenoids-, who are able to close-open the valve body channel with many intermediate values ​​\u200b\u200b(such as a light switch - a rheostat that can make the light in the room brighter and quieter), they began to use this first for forced blocking of the torque converter () and then for softer gear shifting with clutch packs .

This made it possible to make switching almost stepless. It is believed that the gap in power when switching speeds is less than 0.25 - 0.20 seconds is imperceptible to the driver. And given that in 6-speed automatic transmissions the difference between gear ratios is minimized, in fact, in terms of comfort, 6- and 8-speed automatic transmissions are on par with their constructive competitors - CVTs and preselective DSG boxes.

But you have to pay for this advantage with accelerated wear of the clutches. First of all - torque converter clutches.

Frictions operating not in the "on-off" mode, but in the short (or long) slip mode must now meet completely different requirements:

If earlier the On-Off clutch had to instantly “stick together” with the steel surface for quick blocking, then in the case of “controlled slipping”, on the contrary, it should, on the contrary, brake smoothly like a wheel brake block, preventing sharp wheel locks. But unlike the brake pad, there is oil instead of fireproof air between the friction clutch and the body steel.

Several types of carbon and kevlar clutches have been developed ( left) for gas turbine engines, for different tasks and requirements of programmers. And modern "non-replaceable" oils (synthetics) now have a much higher flash point than traditional "semi-synthetic" ones. But this does not solve the problem of burnt oil, but only postpones it.

All the same, the responsibility remains on the drivers to monitor the wear of the clutches through oil contamination. If the oil gets dirty too quickly, then this indicates that the fastest wearing clutches (usually in the gas turbine engine) are eaten up and it's time to change them, otherwise ... ( read above).

Leaders of Friction Modules by replacements in the market of automatic transmissions:

The most popular replacement clutches are the clutches of a large German family from two generations 01M - 01N and their predecessors 096-097 -.
They are also followed by the German bestseller 5HP19 - 177003. In the same pair, French one-way clutches DP0 go side by side: - 144005 .
Next comes a large group of pursuers: CD4E clutch kit - 246003. ( right in the window) Aisinovskaya 09G - 134003, ( on right). and ZF 6HP26-/28 182003 . (left)

Outside diameter:D-122 mm

Inner diameter:D-71 mm

Weight:0.1 kg

Friction discs (brake) designed to fix the winch, and as a result, the load during the operation of the Tadano manipulator.

As practice shows, most of the malfunctions of the manipulator are due to the fact that the kmu winch stops holding the load. Such a breakdown can be caused both by elementary non-compliance with the rules of operation and technical regulations, and by wear of parts of the mechanism, in particular, friction discs.

Cause of failure of friction discs

The main reasons leading to wear of friction discs are:

• ingress of water into the lubricant;
• improperly adjusted discs;
• lack of lubrication in the gearbox;
• use of poor quality lubricant.

Some owners of manipulators, unable to purchase and replace friction discs for the manipulator inexpensively, are trying to solve the problem of breakage on their own, using improvised materials for this. Such amateur performance often leads to a complete failure of the winch mechanism and even to accidents. Replacing friction discs with a manipulator should only be trusted by professionals.

Our company specializes in the sale of spare parts and repair of manipulators, in particular, you can always buy friction discs from us.

We offer a wide range of spare parts for the manipulator, including friction discs at competitive prices, which can be easily seen by looking at the catalog of our products.

Why winch manipulatordoes not hold the load

Sooner or later, owners of Tadano cable manipulators face a problem when the cargo winch does not hold the load, that is, when the load is lifted, it is not fixed and the load falls. To understand why this happens, consider the design of a cargo winch.

As can be seen from the figure, the brake of a friction type cargo winch. Two friction discs and a ratchet between them. These discs are in an oil bath. People call it "wet brakes".

When the friction discs are worn, the required braking torque is not provided and the load falls. This is where the question arises how to change wet brakes.

Why do the friction discs of a manipulator cargo winch wear out quickly?

Why do the brake clutches of the cargo winch of the manipulator wear out quickly? The main reason is the lack of lubrication in the gearbox, lubrication of inadequate quality, ingress of water into the lubrication (most often this happens through a breather), incorrect adjustment of the brake clutches.

According to the instruction manual, brake friction discs should be changed after three years of operation, regardless of their external condition.

What happens in practice? Due to the relatively high cost of friction brake discs for a manipulator cargo winch, their owners begin to invent friction discs from improvised material.

The friction discs of the cargo winch of the manipulators are made by selection from Russian analogues of tractor equipment, and some are even made independently from textolite. But still, the brake of a cargo winch is a critical unit and neglecting its maintenance and unauthorized changes in the design can result in an accident. Do not risk your life and the lives of service personnel. Always use quality materials to repair a cargo winch brake.

Sale and replacement of friction discs

Our company specializes in the sale of spare parts and the repair of manipulators, in particular, you can always buy friction discs from us.

You should be aware that, regardless of condition, clutch replacement should be done at least once every three years. Here you can not only purchase friction discs for the manipulator inexpensively, but also order their replacement, which will be performed by professionals, in accordance with the technical regulations.

We offer a wide range of spare parts for the manipulator, including friction discs at competitive prices, which can be easily seen by looking at the catalog of our products.

How to independently change the brake friction discs of a cargo winch on a manipulator?

It is best to entrust the replacement of friction discs on a truck crane to service centers. Such work should be done by a master who has sufficient qualifications and experience.

How to adjust the brake of a cargo winch

The process of adjusting the brake of the cargo winch of the manipulator is not difficult and it is quite possible to do it yourself. To do this, tighten the castle nut by hand and then unscrew it (loosen) 1/6 of a turn, align it with the hole on the shaft and fix it with a cotter pin. Do not tighten the castle nut with a wrench.

How to independently change a little in the gearbox of a cargo winch of a manipulator

When working with a cargo winch, its natural wear occurs. Air, moisture, dirt gets into the gearbox of the cargo winch. To exclude wear products from the cargo winch gearbox, change the oil six months after the start of commissioning of the truck crane, after which the gear oil is changed once a year. For the operation of the gearbox of the cargo winch of the manipulator, it is necessary to fill it with oil to the middle (about 1 liter)

What oil to fill in the gearbox of the manipulator winch

GL-4 transmission oil is used in the gearbox of the truck crane cargo winch. Recommended oil for use in the gearbox of a cargo winch of manipulators:

1. Mobil Mobilube SAE90

2. SHELL Spirax EP90

3. ESSO Standard gear oil 90

4. Caltex Universal Thuban SAE90