Car carrier system

The supporting system is used for the installation and fastening of all units and mechanisms of the vehicle. It perceives lateral and longitudinal loads, bending and torques transmitted by the engine, transmission and axles of the car, as well as the wheels and suspension as a result of the interaction of the car with the road, acceleration and braking.

The carrier system can be separate element - the frame or the car body itself, therefore all cars are subdivided into frame and frameless (having a load-bearing body).
There are also frame-body support systems, which are often used on buses, where the frame and body base are combined into one structure.

The following requirements are imposed on the car carrier system:

• sufficient strength and rigidity;
• stable mutual position of vehicle mechanisms;
• high manufacturability during operation and repair;
• minimum weight;
• preservation of the kinematic coordination of the operation of the vehicle mechanisms and their performance during bending and twisting of the elements of the supporting system.

The advantages of the frame support system:

• simplicity and reliability of the design;
• manufacturability during production and repair;
• versatility (different types of bodies can be installed on the same frame and conventional and special vehicles can be produced on the same chassis).

For trucksmobiles with a separate body for cargo and a cab for the driver and passengers, the frame structure is the most convenient technical solution.

Load-bearing bodies are used on passenger cars especially small, small and medium classes, as well as on most buses.

The advantages of load-bearing bodies:

• reduction of vehicle weight;
• decrease in vehicle height;
• lowering the center of gravity of the car, therefore, increasing its stability;
• load distribution throughout the vehicle structure, not just in the frame.

The disadvantages of load-bearing bodies are the complexity of manufacturing and repair, as well as low versatility when used on vehicles for various purposes - even minor changes to the vehicle layout require costly changes in the body structure.

Car frame

The frame is the skeleton of the car, that is, its "skeleton". It perceives all external and internal loads arising from the movement of the car and even when it is parked - the weight of the cargo, passengers and the mechanisms and devices placed on it, as well as the moments and forces transmitted by the engine and transmission and chassis units. For these reasons, requirements are imposed on automotive frames:

• required rigidity and strength;
• minimum weight;
• rational shape, allowing a low center of gravity of the vehicle, sufficient travels of the suspension, steering elements and steering angles.

Classification of car frames

Frames are spar and spar (central).
The spar frames, in turn, are subdivided into ladder and peripheral frames.
X-shaped frames are a type of backbone frames.

Spar frames

Ladder spar frame

Ladder spar frame ( fig. 1, fig. 2, a) consists of two spars 1 (longitudinal beams), which are interconnected by cross members 2 ... The spars and cross members have a channel section, with the shelves of the channels facing inward when assembling the frame.
The thickness of the sheet steel from which the side members are made is 5 ... 10 mm... As a material for structural elements of automobile frames, low-carbon steels are used, which lend themselves well to cold stamping.
Sometimes titanium steels are used, which, due to their higher mechanical properties, reduce the weight of the frame by 15…20% .

The side members can be parallel or converge at the front of the vehicle to create free space for steering wheels. In accordance with the distribution of the load on the frames for two-axle vehicles, the largest cross-section of the spar is in the middle of the frame, decreasing towards the ends of the frame.
The variable cross-section of the spars allows you to reduce the weight and consumption of metal without significantly reducing the strength and rigidity of the frame. In addition, this configuration of the side members allows the vehicle's center of gravity to be lowered, which is important for increasing its stability during curved movement and maneuvering.

To reduce the center of gravity, the side member beams in cars and light trucks are often bent over axles and bridges in the vertical plane.

The rigidity of the frame is increased by installing gussets and braces between the side members and cross members. The spars and cross members are fastened together by riveting in a cold state or by welding. The widespread use of riveted joints is due to the good resistance to vibration loads.
Welded frames are very stiff, but more difficult to repair and less durable in places adjacent to welded seams.

The cross members are attached to the side member flanges and their walls. The locations of the crossbars and the shape of their cross-section (box-shaped, trough-shaped, Z-shaped, P-shaped, etc.) are selected based on the uniform strength of the frame along the entire length.

The cross members must be installed at the point where the brackets for the springs, engine, gas tanks are attached, at the places where the balance spring is installed (for three-axle vehicles), and the side members themselves in these places are often reinforced with special inserts.

The cross members are stamped from the same sheet steel as the side members. High ductility steels are used for complex crossbeams. The uniformity of the metal of the frame elements is dictated by the possibility of galvanic currents when using different metals for spars, cross members, rivets and reinforcing elements. Galvanic currents initiate corrosion and can cause other problems in vehicle operation.

For the frames of vehicles of large and especially large carrying capacity, rolled profiles made of low-carbon low-alloy steels are used. The material of rolled sections has higher mechanical characteristics than sheet steel. However, the mass of such frames is greater, since the side members have the same cross section along their entire length.



Peripheral frames

Peripheral frames ( fig. 2, in) can be used in the structure of the supporting system of passenger cars. The side members of the peripheral frame run along the periphery of the car body floor and create a natural threshold for it. This increases the body's resistance to side impacts.

The free middle part of the frame allows the floor of the body to be lowered, thereby increasing the stability of the vehicle. To increase the wheel travel of the car, the side members are bent in a vertical plane over the front and rear axles. The middle portion of the frame is located below these folds.

Spinal frames

Spine frame ( fig. 2, d) consists of one central bearing beam 9 to which the crossbars are attached 10 and various mounting brackets. The central beam, inside which the cardan transmission is located, has a tubular section.
If on passenger cars the backbone frame is usually non-separable, trucks The central beam consists of the crankcases of individual vehicle transmission units, which are interconnected by special pipes.

Brackets are installed between the crankcases and branch pipes for fastening the cab, cargo body, engine and other units. Such a split backbone frame is universal, since, by changing the length, it is possible to create families of cars with different numbers of driving axles and with different bases on the same unified units.
The backbone frame reduces vehicle weight by 15…20% , since the transmission units themselves form the frame elements. The center frame has higher rigidity than the spar frame, but such a frame requires the use of alloy steels for the manufacture of transmission housings and connecting pipes, as well as high manufacturing accuracy. In addition, during the maintenance and repair of the car, access to the transmission mechanisms is difficult and partial and sometimes complete disassembly of the frame is required.

X-shaped frame ( fig. 2, b) will increase the steering angles, thereby improving the vehicle's maneuverability. This frame also makes it possible to lower the floor of the body, the center of gravity of the vehicle, increase its static and dynamic stability.

Additional structural elements of automobile frames

Brackets for springs, shock absorbers, fenders, footrests and other elements of the car body and cab are attached to the frame.
At the front end of the frame, a buffer and towing hooks are installed. The buffer is designed to absorb shocks and shocks during collisions and collisions. The towing device is located at the rear of the trucks.
The front engine support is installed on the reinforced front cross member.

Car towing device

The towing hitch (or, as it is usually called, the tow hitch) is designed to couple vehicles with trailers and to mitigate axial shocks arising from the movement of the road train.

Traction coupling (towing) device ( fig. 1, b) is a steel forged hook 18 , on the rod of which between two thrust washers 9 and 20 rubber elastic element installed 10 tightened by a nut 8 ... Hook bar complete with buffer placed in the housing 11 , which together with the lid 19 bolted to the rear cross member of the frame. The end of the rod protruding from the glass with a cotter nut on it 8 closed with a cap 7 .
Latch 17 the hook is locked by a dog 13 installed on the axle, as well as a safety cotter pin 14 connected by a chain 16 and entering the hole of the dog 13 .

Dump truck subframe

The supporting system of dump trucks, in addition to the main frame, includes an additional shortened frame - a subframe on which cargo body and the elements of the body lifting mechanism are attached. The subframe reduces the load on the rear of the vehicle's main frame when lifting the body during unloading by taking some of this load and distributing it evenly over the main frame. The subframe is welded from stamped sheet steel. It is attached to the tipper frame with ladders and bolts.

On fig. 3 the subframe of the KamAZ dump truck is shown, which consists of two spars 3 connected by cross members 2,4,8 and 11 ... At the rear, where the greatest loads occur, the subframe has an X-shaped reinforcement 6 , and its spars are equipped with amplifiers 7 .
Crossbars 2 and 11 have a trough-shaped section, the rest of the cross-members have a channel section.
Brackets for attaching the subframe to the frame are welded to the side members 10 , limiters of lateral movements of the subframe, brackets of rubber-metal supports 1 bodies and brackets 9 body tipping axles. To the crossbar 11 the lower support of the hydraulic cylinder of the body lifting mechanism, the control valve and the valve for limiting the body lift are attached.
On the crossbar 2 installed rubber-metal support 5 , which serves to fix the body in the transverse direction. On the crossbar 4 the bracket for the safety cable of the body rollover limiter is fixed.

Frameless supporting systems of cars are considered in the section "

The load-bearing part is one of the most important components in the device of the car, because it is thanks to it that all the components of the car can be assembled into a single whole.

Now several types of bearing parts are used, each of which has found application on certain types of cars. Initially, all cars were built on the basis of a frame bearing part. But over time, it was replaced by other types, for example, it is used on almost all passenger cars, in which the frame is absent, and all its functions are performed by a reinforced body. And yet the frame bearing part continues to be used - on trucks and SUVs.

Purpose, types

The car frame is a girder structure that acts as a base for all component parts auto - power plant, transmission units, chassis and others. The body, present in the structure of the supporting part, performs only some functions - it provides space for passengers and cargo, and also acts as a decorative element.

The main positive quality of using the frame is the high strength of the bearing part. It is because of this that it is used on trucks and full-fledged SUVs. But at the same time, due to the frame, the total mass of the car is increased.

Also, the car frame allows you to unify components and mechanisms between models to the maximum. different classes... At one time it came to the point that many automakers produced a car chassis with all the main parts (frame, engine, transmission, running gear), on which different types of bodies were "pulled".

At the same time, several types of frames were developed, each of which has its own design features. All of them can be divided into:

1. Spar
2. Spinal
3. Spatial

Some of these types have subspecies; combined types are also often used, in the design of which there are constituent elements of different frames.

Spar and its subspecies

The spar frame of the car is the most common. Its design includes two longitudinal power beams - spars, stretching along the entire body and interconnected by cross members.

Spar frame Toyota Land Cruiser

The spars themselves are made of steel, and to ensure high torsion rates, different types of cross-sectional profiles are used - box, I-beam, channel.

Moreover, it is not necessary that they be even, many spars have bends in both the vertical and horizontal plane. For example, on some cars, the frame is curved at the front and rear (in the area of \u200b\u200b\\ u200b \\ u200bthe wheels), which allows you to move the center of gravity down.

In addition, the side members are placed both in a strictly horizontal position relative to the floor, and can be at an angle. The second option is used on SUVs.

The side members are connected by cross members, which can be positioned in different ways. In the so-called ladder-type frame, the cross members are fastened perpendicular to the side members (considered classic). But there are also structures in which these components are located at angles - K-shaped and X-shaped frames.

Spar x-frame

Welding (in off-road vehicles), rivets (trucks) are used to connect the side members with cross members. In some cases, bolted connections are used. For fastening the nodes of the car, both side members and cross members are equipped with brackets.

A subspecies of the spar frame is peripheral. Its distinctive feature is the large distance between the side members. After the car is fully assembled, they are located near the body sills, which significantly increases the resistance to side impacts, and also allows the floor level to be lowered (as much as possible).

Corvette Peripheral Frame

Another type of spar frame is X-shaped. The essence of the design of such a frame boils down to the fact that in the front and rear parts the side members are divorced, and in the central part they are brought together to the maximum (the space between them only allows the transmission shafts to be placed). Outwardly, this type resembles the letter "X", hence the name.

Another option is a supporting base. Longitudinal spars are still used in the design of this frame, but here they are interconnected not by cross members, but by the bottom. In this case, the supporting base, although the bottom enters into it, is not an element of the body, therefore this type belongs to frames.

Bearing base

Spine frame

Backbone frames are less common and, in fact, are used only on Tatra trucks. The main component of this type of load-bearing part is a central beam made of a pipe.

Spine frame

It is noteworthy that in such a frame, some auto units are used as load-bearing elements, namely the motor, gearbox, main gear housings. All of them are interconnected by a central beam, while rotation between the nodes is carried out using shafts located in the pipe.

The design feature of the rear driving axles is that the transmission of rotation to the wheels is carried out by shafts with cardan joints, and not half shafts, since the main gear housings are rigidly attached to the beam. But such a device, in turn, makes it possible to install a car on all wheels.

The main advantages of this type of frame are high torsional stability and the possibility of relatively simple creation of multi-axle chassis. To do this, you just need to add the required number of final drives and connect them using a central beam.

But this car frame did not become widespread due to the complexity of maintenance and repair of transmission units, since for this you have to disassemble almost the entire frame in order to disconnect the main gearboxes and the gearbox. In addition, the body, fixed to the pipe, is located quite high above the ground. Therefore, this type of frame is only suitable for use on trucks.

Spatial frame

Spatial is the frame of a car, presented in the form of a frame welded from pipes. Differs in low weight and high strength indicators.

This frame forms not only compartments for placing and securing the components of the car, but also a cabin for passengers. In addition, the frame also plays the role of a body, which is simply absent in a car with such a frame, and the decorative trim is fixed directly to the composite pipes.

Such a frame has found application on sports cars, as well as homemade models - buggies. It is noteworthy that even on mass-produced cars with a monocoque body, which are altered for participation in competitions, they are equipped with an internal tubular frame to increase the rigidity of the body. But in this case, the frame to be installed cannot be called a full-fledged spatial frame.

Combined views

The above are the main types of frame bearing parts. But, as noted, there are many variations that are combined types.

These include the forked frame. In this type, there are the main components of the spar and backbone types - the central beam and the spars. The design looks like this: in the front and rear parts, longitudinal spars are used to fasten the car units, and a pipe is installed in the central part (but here it is not used to accommodate the drive shafts). The beam and the spars are rigidly connected to each other.

Fork frame - symbiosis of several types, and it is not the only one. On some cars, structures were used, consisting, for example, of components of an X-shaped frame and a supporting base, or a central beam and spars (unlike a fork, spars are located only in front).

But there are also options that combine different types of load-bearing parts - the frame and the load-bearing body. The so-called integrated frame belongs to this type. Its essence boils down to the fact that the frame elements (classic spar or peripheral) are included in the body structure and are made with it at the same time (they are rigidly connected to each other). But it should be noted that the side members are usually located only in the front and are designed to fix the power plant.

Integrated frame with body

Another variant of the combined load-bearing parts is the body with a subframe. This element performs the same functions as the side members in the integrated version, but in contrast to it, it is attached to the body using bolted connections.

Finally, we note that although the frame is used only on cars of certain classes, the elements included in the design are used quite widely even now, since they increase the rigidity of the load-bearing bodies. Reinforcing spars or subframes can be found in almost any passenger car.

The resulting design is called the chassis. Frame chassis in most cases can even move on the road separately from. The history of the frame chassis goes back to the very beginning of the development of the automotive industry. The separate frame was a fully automotive solution. Car designers borrowed this idea from rail transport. The first frames were made of hardwood. In addition, round metal pipes served as the material for frames in those years.

At the beginning of the twentieth century, frames with a construction of stamped profiles with a rectangular cross section were very popular. Closer to the 30s of the XX century, many companies producing passenger cars vehicle abandoned the use of frames in favor of a self-supporting body. Today frame chassis are used mainly on machines with cargo platform and tractors, however, many SUVs and limousines are often equipped with frame structures. The latter require the installation of a frame, because the supporting body with such a solid length of the machine is overweight.

Any car frame has inherent distinctive feature in terms of design. It consists in the separation of the functions of the supporting body parts and its panels that have decorative value. The decorative panels can also be fitted with a reinforcing frame. Such a frame can be located, for example, in the area of \u200b\u200bdoorways, but in this case it does not take part in the perception of power loads that make themselves felt during the movement of the car. The most common is classification of car frames depending on the supporting structure used. There are spars, spine, peripheral, fork-spine, lattice frames, as well as supporting structures integrated into the body.

Part spar frame includes several cross members, which are sometimes called "traverses", a pair of longitudinal spars (this is the name of the main load-bearing element of the supporting structure, which is a box of complex shapes made of metal), brackets and fasteners designed to install a car body and various units on them. Both cross members and side members can vary in design and shape. There are X-shaped, K-shaped, and tubular crossbars. Their purpose is to give the structure the highest possible rigidity. For the manufacture of traverses, a bent metal profile is usually used. For side members, the most characteristic is a U-shaped section (channel) that is variable in length. In the most loaded areas, the height of the channel section is increased.

The side members can be parallel to each other or at a specific angle. In addition, the side members can be installed bent in a vertical or horizontal plane. The parallel arrangement is used mainly on commercial vehicles. The rest of the schemes are well suited for SUVs - cars with increased cross-country ability... By installing the side members at an angle, you can achieve the maximum angle through which the steered ones turn. Vertical bends are made to lower the center of gravity. At the same time, the floor level in the car also becomes lower. Due to the bending of the side members in the horizontal plane, in addition to lowering the floor level, a significant increase in the level of passive safety is achieved in the event of a possible side collision.

To connect the parts that make up the frame, bolts and rivets are used among themselves. Welded joints are also widespread. Riveted frames are more often used in truck structures, and welded frames are more often used in manufacturing passenger cars and dump trucks with heavy lifting capacity. Bolts have found application in small batch production. Almost all are equipped with spar frames trucks and SUVs. It is the popularity of such structures that is due to the fact that the concept of "frame" most often means just a spar bearing system.

The development of the backbone frame was carried out by the Czechoslovak company "Tatra" in the 20s of the last century. It was with such frame chassis that many cars produced by this enterprise were equipped then. The main structural element of the backbone frame is the central transmission tube, on which the crankcases of the power unit and such units as, are combined.

The installation of such a frame is accompanied by the need for car equipment independent suspension all wheels, which in most cases is realized by attaching a pair of swinging wheels to the ridge at the sides (each of them has one hinge). The main advantage of this scheme is its high torsional stiffness. In addition, it becomes possible to develop all sorts of modifications of cars with different numbers leading bridges. The main disadvantage is the difficulty of repairing units that are rigidly fixed to the frame. This is the reason for the low popularity of backbone frames in the modern automotive industry.

Fork-spine frames

A kind of variation of the type of frame discussed above is the fork-spine structure. Here, the front, and sometimes the rear, are made in the form of forks formed by a pair of spars that serve to attach the power plant and transmission units. Such a frame differs from a conventional center frame in that the power train housings are manufactured separately. Many experts include here the so-called X-shaped frames, which are sometimes called a type of spar installations.

Peripheral frames

The peripheral frame is also often viewed as a variation on the side member design. In the central part of the peripheral frame, the distance between the pair of side members is made so large that, after the body has been installed, the side members can be found directly behind the door sills. The "Achilles' heel" of such a frame is the places where the transition from the increased distance between the side members to the normal one is carried out. In these places, special box-shaped reinforcements are mounted, analogs of which are often found in cars with a monocoque body. The use of the peripheral structure results in a significant lowering of the body floor, which is entirely located between the side members, which ultimately reduces the overall vehicle height.

Lattice frames are sometimes referred to as space or tubular frames. Such a system is a iso-truss, for the manufacture of which relatively thin pipes are used. These pipes are made of high strength alloy steels. In addition, this material should be lightweight and torsionally strong. Tubular structures have found application in racing and sports cars, because for them one of the important parameters is the minimum mass at maximum strength. The frame integrated into the body has no significant structural differences from the usual one, but it is connected to the body by welding.

To the main advantages of frame structures car include: simplicity, fairly low cost, the possibility of unification basic models vehicles, the perception of serious loads while driving, increasing comfort, providing better noise insulation. In addition, repairing a car with a frame after a traffic accident is much easier than repairing a car with a monocoque body. The disadvantages of the frames are the increase in the mass of the car (when compared with the monocoque body), as well as the worst passive safetyassociated with the difficulties arising in the creation of zones of programmed deformation.

Long-term studies have shown that during the movement of a car, uncontrollable forces act on the body, proportional to the mass of the car at a given moment and its speed, which act in three directions - vertical, horizontal and frontal - and cause such types of deformation of body elements as bending, compression, twisting. The task renovation works is the restoration of the projected endurance of the body components according to the manufacturer's specifications. The repair technology must be such that the endurance of the repaired parts matches the non-repaired car parts.

In vehicles with a monocoque body, the frame functions are either performed by the body itself, or the frame (or subframes replacing it) is structurally integrated with the body and cannot be separated from it without violating the structural integrity. Typically, the body is attached to the frame using bolted brackets with thick rubber pads to reduce vibration.

All units are attached to the car frame: engine, transmission, axles, suspensions. Together they form the chassis. The frame chassis is a complete structure that can exist and move separately from the body.

Currently, frame chassis is used mainly on tractors and trucks, but in the past, many passenger carsmobiles also had a frame chassis. "Rigid" SUVs often have a separate frame.

There are the following types of frames: spar, peripheral, spine, fork-spine, supporting base, lattice (they are also tubular).

Spar frame with X-shaped cross member

The spar frames are composed of two longitudinal spars and several cross members, called "traverses", as well as attachments and brackets for body and assembly mounting.

The shape and design of the side members and cross members may vary; distinguish between tubular, K-shaped and X-shaped crossbars. The spars, as a rule, in cross-section represent a channel, and the length of the section usually changes: in the most loaded sections, the section height is often increased. They can be located both parallel and at some angle relative to each other.

Peripheral frames

Sometimes considered as a type of spar. With such a frame, the distance between the side members in the central part is increased so much that when the body is installed, they are directly behind the door sills. Since in the places of transition from the usual distance between the spars to the enlarged frame, the frame is weakened, in such places special box reinforcements are added, in English-speaking countries called the term torque box.

This solution makes it possible to significantly lower the body floor, placing it completely between the side members, and therefore to reduce the overall vehicle height. Therefore, peripheral frames have been widely used in American passenger cars since the sixties. In addition, the location of the side members directly behind the body sills contributes greatly to the safety of the vehicle in a side impact.

Spinal frames

The main structural element of such a frame is the central transmission pipe, which rigidly unites the crankcases of the engine and power transmission units - clutch, gearbox, transfer case, the main gear (or main gears - on multi-axle vehicles), inside which there is a thin shaft, which replaces the cardan shaft in this design. Independent suspension of all wheels is required.

The advantage of this scheme is high torsional rigidity; in addition, it allows you to easily create modifications of vehicles with a different number of driving axles. However, the repair of the units enclosed in the frame is extremely difficult. Therefore, this type of frame is used very rarely, and has completely fallen out of use on passenger cars.

Fork-spine frames

A type of backbone frame in which the front, sometimes the rear parts are forks formed by two spars and serve to mount the engine and units.

Unlike the backbone frame, the power train housings are usually (but not always) made separate, using a conventional cardan shaft... Such a frame had, among others, the representative cars "Tatra" from T77 to T613.

X-shaped frames are often referred to the same type, which are considered by some sources as a type of spar frames. Their spars in the central part are very close to each other and form a closed tubular profile. This frame was used on soviet cars "Seagull" GAZ-13 and GAZ-14 of the highest class.

Bearing base

This frame is integrated with the body floor for increased rigidity.

This design had, among others, the Volkswagen Beetle and the LAZ-695 bus. At present, this scheme is considered quite promising due to the possibility of building the most different carslike on the platform.

Lattice

Also called tubular frames or spaceframes.

Lattice frames look like a space truss with a very high torsional stiffness-to-mass ratio (i.e. they are lightweight and very torsionally strong).

Such frames are used either on sports and racing cars, for which low weight with high strength is important, or on buses, for whose angular bodies it is very convenient and technologically advanced in production.

When it comes to repair technology, the question often arises of how to repair or change an element that is load-bearing in terms of its design features. For example, consider a frontal oblique deformation of the front of a car in which the front panel, hood, fender, mudguard, and spar are deformed. Of these, in this unit, two removable elements can be distinguished - a wing and a hood - and three or more welded ones - a radiator frame, a mudguard, a spar. During the repair work of deformed elements, it is necessary to ensure the functions laid down by the manufacturer (symmetry of the structure, symmetry of the shape of the body and its elements, the safety of passengers while driving, etc.).

Therefore, if we accept the repair of the mudguard and fender, then the hood, radiator frame and spar must be replaced. When replacing the hood, it is possible to control the repaired wing surface at the point of abutment to the hood, to control the location of the radiator frame when replacing it and the adjoining of the repaired mudguard to it. When replacing the radiator frame, it is possible to control the geometry of the hood opening, the correct abutment of the mudguard to the upper part.

When replacing the spar, it is necessary to ensure the strength of this unit, weakened by the repair of the mudguard and wing. In this case, it must be borne in mind that conditionally repairs will be applied to the wing and mudguard without heating and welding. If heating is applied to one of the repaired elements to shrink the metal or welding a gap or technological cut, then the other element must be replaced with a new one. In this case, it is most expedient from an economic point of view to replace the wing. If a decision is made to repair the complete spar, that is, the U-shaped spar itself with slight heating, then the amplifier must be replaced when editing, whether it be a separate amplifier, which is an amplifier, a mudguard or other element.

It should also be remembered that although the structural endurance of the body elements was designed by the manufacturer for a safety factor of n \u003d 1.3-1.5, and for the edges of the body, which are subject to the combined action of turbulent forces generated by the gearbox and wheels while driving, the safety factor is even 1.5-2.0, without proper equipment, technological maps and load distribution diagrams during road accidents, we cannot determine how the repair factor will affect the safety of passengers in the event of deformation in the future.

Considering that the technology of repair work should bring the endurance of the repaired parts of the car in line with the unrepaired ones, the ideal option for repairing this unit would be to replace all elements that cannot be fixed without the use of heating or welding of technological cuts.

An example of a spar repair on a frame car

The right side member under the passenger seat floor is struck through corrosion to such an extent that the arm brackets front axle not only unable to perform their functions, but also come off.

For repair, a used spar with a mudguard was purchased, from which the necessary parts were cut.

In order to reliably place the support under the threshold, it had to be replaced, and also partially replaced the floor.

After that, the levers of the front axle are removed, the damaged part of the side member is cut out and replaced. The work is not easy, because the cutouts for load distribution are made difficult, sometimes it is difficult to access them for welding, and it is necessary to apply seams on both sides.

The photo shows the floor reinforcement, on which the pad is welded, which is welded to the side member.

We weld the repair parts to the floor, protect the joints with sealant from all sides.

We apply an anti-gravel coating to all the places being repaired, carry out the internal anti-corrosion treatment of the threshold and the side member and get the result of the repair.

If the collision of the car has resulted in significant deformation, the mechanical units must first be removed - this is the only way to thoroughly straighten the folds and replace parts that cannot be repaired. In addition, it will allow to remove residual stresses that may arise and remain after straightening. When the vehicle is in motion, residual stresses can cause stresses in the mountings of the shock absorbers and bushings, and sometimes rupture.

However, in some cases, pre-straightening the body with installed mechanical units can facilitate access to units to be removed, for example, the engine unit in front-wheel drive vehicles, to the front or rear axle... In this case, care must be taken to replace the mounting bolts and shock absorbers. This operation is performed at the stand.

If the impact to the front or rear half-axle caused deformation of the body base, you can also straighten the body by fixing (engaging) the stretching mechanism on mechanical units, such as wheel rims or suspension arms that have received deformation. Editing is done in the direction directly opposite to the impact. Such an operation is possible only when the impact has come directly to the front or rear half-axle, and its replacement is necessary.

It is also imperative to replace the ball joints and tie rods. Straightening with a jack or other hydraulic mechanism used to restore the shape or straighten a deformed part. However, getting down to work, do not forget that with a very sharp editing of a body part, deformation of the adjacent zone may occur. Therefore, when stretching, i.e. simultaneously with the action of the jack, it is recommended to accompany the restoration of the linearity of the body by tapping the folds. And after drawing with a jack, it is necessary to remove all internal stresses by tapping (with a straightening hammer) the entire section that has been straightened.

To be sure that later there will be no reverse movements of the straightened sections of the body due to residual stresses, the surface is tapped through the wooden lining in the direction of the impact. If the straightened body does not change its shape, then the straightening operation is performed correctly. If not, straightening must be done again until the geometry is within the tolerances specified by the vehicle manufacturer.

If the vehicle is hit by a side impact, it causes deformation of the base of the body, accompanied by a decrease in the length of the body on the side of the damaged surface, which is easy to identify. When editing at the stand, the performer must take this circumstance into account. In practice, straightening is carried out by stretching in two directions simultaneously: lateral and longitudinal, which makes it possible to restore the original geometry of the body base.

An example of a side surface restoration is a center post straightening that is wrapped around with a pull chain. To protect the rack from damage and evenly distribute the force between the rack and the chain, a wooden plank is laid.

Longitudinal stretching performed simultaneously with lateral stretching can be performed in various ways. If the deformation is concentrated in the lower part of the body, the base is straightened directly by fixing the clamps to the sill flanges. The jack is placed between two clamps and under pressure moves them in the longitudinal direction as the simultaneous lateral stretching is carried out. If the deformation is concentrated at the top of the body, stretching is done longitudinally from the front and rear of the body.

Work on straightening and checking new side members must necessarily be carried out using precision equipment, which is available only in workshops.

In any case, it is best to diagnose geometry using good equipment, the choice of which will be discussed in the next issue.

When preparing this article, materials from open sources were used in accordance with the GNU Free Documentation License.

A frame car is the unambiguous choice of most motorists. Why is a frame car attractive? Types of frames, their advantages and disadvantages. Well, if someone is not familiar with what a frame on a car is and why it is needed, read this article especially carefully. This is an important characteristic of the car and you need to know it!

What are the types of car frames.

Each car is a collection of mechanical components and assemblies attached to the supporting part. In some cars, the supporting structure (base) is body, other's - frame or stretcher.

At the dawn of the automotive industry, frame construction was used on all types of vehicles. Later, when it turned out that the installation of the frame was unjustified due to the large weight and high cost of manufacturing on passenger cars, they began to use a supporting body as a base.

A frame structure is still installed on trucks, high-traffic vehicles.

The advantage of the frame is that it provides the best rigidity and strength of the structure for breaking, twisting, stretching compared to other types of load-bearing part. This factor directly affects the carrying capacity of the vehicle, its off-road qualities.

The main types of car frames:

• Spinal;
• Spar frame

These types have their own varieties. For example, fork-spine refers to spinal frames, peripheral - to spar.

Spar frame

The most common frame design today.

Such a frame has two longitudinal spars and several cross members. Spars are made from a U-shaped profile (channel). The higher the load, the greater the height and thickness of the profile.

The cross members have different design features. There are X- and K-shaped crossbars, as well as straight shapes. To install the mechanisms and assemblies of the car on the side members and cross members, various fasteners and brackets are used. Riveted, bolted, welded and other joints are used to fasten the frame parts.

Peripheral frame

It differs from the usual spar in that the spars were bent during manufacture so that there was the greatest distance between them. This is to keep the underbody as low as possible. Such frames were made and installed on american cars until the 60s of the XX century.

Spine frame

In the mid-20s of the last century, the Czechoslovakian company Tatra developed a backbone frame.

The supporting part is made of a pipe, inside which all the transmission elements were located. With this pipe, the engine was connected to the transmission. Power unit, gearbox and main gear, the clutch is part of the frame elements. All these elements are rigidly fixed to the frame.

With the help of a cardan shaft located inside the tube, the engine transmits torque to the transmission units. Only when all wheels are provided with independent suspension, it is possible to install the frame on the car.

Fork-spine frame

It was also invented in the Tatras. The engineers of this company abandoned the rigid attachment of the transmission and engine to the load-bearing central tube, as was done on spinal frame... AT new design special forks appeared on both sides of the carrying pipe, on which the engine and transmission are installed.

The main advantages frame structure in front of others:

• high level of comfort (low noise and vibration),
• high lifting capacity, simple design
• ease of repair and maintenance, cheapness of parts.

disadvantages:

• volume decreases car interior,
• more weight of the machine (increased fuel consumption)
• low passive safety (due to the impossibility of programming the crumple zones)
• an increase in the total price due to the cost of the frame.

Currently, passenger cars are made with a monocoque body, and real (not SUVs) SUVs are made on a frame.

When buying an SUV, you can roughly determine the class of the car by the presence or absence of a frame.