A frame is a rigid element of a car, which takes on the main loads and is used to fasten the rest of the elements on it, represented by the transmission, the body and various equipment. In contrast to the alternative monocoque body, the frame in most cases is flat and is a kind of "pivot" that gives rigidity to the entire structure as a whole. In fact, the frame structure of the body is the basis around which the car is assembled - which makes it much easier to manufacture and maintain than other types of layout.

There are many types of frames used in the automotive industry. The most common nowadays is the straight spar frame, which is created from two longitudinal metal beams that run the entire length of the body. In certain places, they are connected by crossbeams - the so-called traverses, which give this element of rigidity and are intended for fastening individual units. A special modification of the longitudinal frame is the peripheral design, which implies a significant increase in the distance between the longitudinal members in the center of the body. Such frame ones have a fairly low lowered floor, which is located between the beams, which play the role of thresholds.

There are also exotic options - in particular, the backbone frames, in which the central tube acts as the supporting element, in which the transmission shafts pass. It allows you to significantly reduce the weight and dimensions of the car relative to the case of using a classic spar frame, and also makes it possible to use. However, it also has its drawback - the complexity of vehicle repair, for which it is necessary to completely disassemble the car.

Video on how the SUV frame structure works:

It is also necessary to mention the lattice frames used in - they create not only a load-bearing base, but also a safety cage on which light body panels are hung. Sometimes the frame structure of a car is combined with a monocoque body - in this case, we speak of an integrated frame that takes only part of the load. By the type of connection, the frame parts are divided into the following types:

• Riveted - easy to manufacture.
• Bolted - have increased strength, but very high labor intensity of assembly.
• Welded - and durable.

The most important benefits

If you look at the list of frame cars for passenger cars, you can see that most of it belongs to large SUVs such as Toyota Land Cruiser, Nissan patrol, and so on. This is not surprising - the frame can carry heavy loads compared to the monocoque body. Due to this, the best cross-country ability is achieved - the car does not deform when overcoming significant slopes and serious obstacles. Also, an increase in permissible loads contributes to an increase in the mass of the transported cargo. This is why most commercial vehicles is built on the basis of a rigid frame.

UAZ Patriot - representative of frame vehicles

From the point of view of manufacturers, the frame is also more preferable - it is easier to attach the main units to it and attachments... It is more convenient to pass such a structure through a conveyor - it can be assembled separately from the body, which significantly speeds up the process of manufacturing a vehicle, allowing it to be divided into two technological chains. The workers will also speak in favor of the frame - when using it, it is much easier to restore the geometric integrity of the body. In the case where the damage is too severe, you can simply replace the frame, which has a lower cost than the ready-to-use monocoque body. However from frame structure the majority refused - therefore, there were reasons for that.

Cons of a rigid base

Even the use of modern materials is not able to significantly lighten the frame or reduce its dimensions - it will still weigh down the car, and force it to big sizes without a significant increase in the useful volume inside the body. Consequently, emissions increase exhaust gases and significant damage to the environment occurs. On the scale of a narrow segment of SUVs, this is not very important, but if the majority passenger cars will have a similar layout, all the advantages of the car's frame structure pale before such problems. In addition, an increase in mass means an increase in the load on undercarriage... Springs are not always able to cope with the weight of frame vehicles, so they are often replaced with more durable, however, not so comfortable springs.

It is worth saying and. When using the frame, there is no indestructible connection between it and the rest of the body. Accordingly, when a very strong impact occurs, the various parts of the vehicle are displaced. This leads to very serious consequences, in particular, injuries to passengers or even death. Consequently, the main reason for rejection of the frame by most manufacturers is the changing requirements for modern car, which should be as safe and economical as possible.

Who needs a frame?

Knowing what “frame car” means, we can easily conclude about the purpose of such vehicle... They are suitable for use as commercial vehicles as well as special vehiclesdesigned for very heavy work. In addition, an SUV, which is not designed to overcome city curbs, is a must-have. If you definitely do not need such cars, you should pay more attention to modern cars with a monocoque body. They are more fuel efficient as well as safer and more practical.

Each car is a collection of mechanisms and systems attached to the carrier. Cars are produced in which it plays the role of a supporting part, but there are cars in which all mechanisms and systems are installed on the frame.

Car frame

At first, the frame structure was used on all types of cars, but over time, the carrier began to be used in the production of passenger cars, and the frames are still used, but only on trucks.

They did not abandon frame structures in the production of off-road vehicles, so most SUVs also have a frame bearing part. The advantage of using a frame is to provide a more rigid vehicle structure, which in turn makes it possible to transport large loads.

Types of car frames

The use of frame structures on cars began almost at the dawn of the automotive era. During this time, several basic types of car frames have been proposed:

• spar frame;
• and spinal.

Each of these types of frames comes in different varieties. A type of spar frame is the so-called peripheral frame. And in addition to the backbone frames, cars with fork-backbone frames were also produced.

Spar frame

The most common frame structure is the spar frame.

Spar frame device toyota car Land Cruiser 200:
1 - front suspension mounting bracket; 2 - cross member; 3 - spar; 4 - body fastening bracket.

This frame consists of two longitudinal side members as well as cross members. The side members are made of channels with different section heights. In places that will be more loaded, the height is increased.

Crossbars can also have different designs, there are ordinary, straight shapes, as well as K- and X-shaped. To ensure the installation of vehicle mechanisms, brackets and mounts for them are installed on the side members and cross members. Rivets, bolts or a welded joint can be used to fasten the frame elements together.

A distinctive feature of the peripheral frame from the usual spar is that during the manufacture of the spars they were bent, which led to the fact that in the middle between the spars there was the greatest distance between them. This was done in order to be able to position the bottom of the car as low as possible. Used such frames in America in the production passenger cars.

Spine frame

Backbone frames for cars were developed by specialists of the Tatra company. And such frames were used mainly on cars of this company. The main bearing part of the backbone frame is a pipe that connects the engine and all elements.

Frame of Tatras

In fact, power unitas well as gearbox and main gear are also frame elements. The fastening of all these mechanisms is rigid. The torque from the engine to the transmission elements is carried out by the shaft, which is installed inside the pipe. The use of such a frame structure is possible only if all wheels of the car are provided with an independent suspension.

The backbone frame is good in that it provides high torsional rigidity, easy and fast creation of cars with a different number of driving axles, but since some of the car mechanisms are inside the frame structure, renovation works rather difficult.

Fork-ridge frames were also developed by Tatra employees. In this case, they abandoned the rigid attachment of the engine and transmission to the load-bearing central tube. Instead, they installed special forks on both sides of the carrier pipe, on which the engine is installed with.

Under car frame refers to the type of load-bearing system of a beam structure that is currently used on passenger cars high cross-country ability, some models sports cars and trucks.

Car frames work under high loads and are a critical part of the car. Frame weight trucks with buffers and brackets assembled up to 10-15% of its own weight. The upper limit applies to heavy-duty vehicles in the frames of which rolled profiles are used.

Various steels are used for the manufacture of car frames. The choice of steel grade is dictated by a number of considerations, the main of which are determined by operational and technological requirements. To meet the operational requirements, the steel must provide the frame structures with the necessary strength throughout the entire service life. To meet the technological requirements, the steel must be capable of making frames and all of its parts using modern production methods. Steel should have sufficient ductility, have stable mechanical properties, and be welded well.

Theoretical and experimental studies in the field of the cyclic strength of truck frames have shown that the most dangerous stresses and failures of automobile frames are the result of skew-symmetric loads arising from the torsion of the vehicle carrying system.

Until now, in the practice of designing automobile frames for trucks, the practice of performing strength design justifications for newly created structures has not been established. The design is carried out mainly according to prototypes, taking into account the calculation for bending from a static load with the selection of the optimal value of the safety factor. The fine-tuning of the frame structure is partly carried out in bench and field conditions, but mainly transferred to the stage of operational tests. At the same time, there are already the results of numerous studies devoted to the development of methods of strength calculations using a computer and methods of accelerated bench tests with simulation of loading modes typical for operation and control of tests using a computer. They allow obtaining the necessary information on the strength and durability of the frame structure at the design stage.

The advantages of the frame structure of the supporting system are simplicity, low cost, perception of significant loads, unification basic models car. However, the use of the frame increases the weight of the vehicle. When designing and manufacturing automobile frames, it is difficult to implement zones of programmed deformation in the front and rear, thereby reducing the level passive safety.

Almost all components and assemblies of vehicle systems are attached to the frame: body, engine, transmission, front and rear suspension, control systems, etc. Together they form the chassis of the vehicle.

Depending on the design, the following main types of frames are distinguished:

• spar,
• spinal or central,
• lattice or spatial,
• combined.

The most common are spar frames.... The spar frame combines two longitudinal beams (spars) and the cross members between them.

The spar is a metal beam of open or closed cross-section (closed box, channel, I-beam) with high bending rigidity.

Depending on the type of car, side members can be installed:

• parallel in the horizontal plane;
• at an angle in the horizontal plane;
• curved in a vertical plane;
• curved in the horizontal plane.

The parallel spar frame arrangement is mainly used on trucks. The rest of the schemes are used on off-road light vehicles. The arrangement of the side members at an angle allows you to achieve the maximum steering angle. The bends of the side members in the vertical plane provide a decrease in the center of gravity, and accordingly low level floor in the back of the car. The side members, curved in the horizontal plane, lower the floor level in the body, and also increase the level of passive safety in a side collision.

The cross members serve to stiffen the frame structure. The crossmembers can be straight, K-shaped or X-shaped. The cross members are made of a bent metal profile.

The spars and cross members are connected to each other by riveting ( trucksmobiles) or welding (cars). To fix the body, engine, transmission units, brackets of various shapes are installed on the frame. Various technological holes are made in the body of the side members and cross members.

The backbone frame consists of a longitudinal support beam and cross members attached to it. As a rule, the central beam has a tubular section. Inside the beams are located individual elements transmissions. The backbone frame has a higher torsional rigidity compared to the side member frame. The backbone frame assumes independent suspension all wheels. Due to the complexity of the design, the backbone frame has not been widely used and is rarely used today.

The lattice frame is used in the construction of sports cars and buses. In essence, it is similar to a monocoque body. The lattice frame provides high torsional rigidity with a relatively low weight.

Carrying system requirements

From the main purpose of the supporting system - to combine all parts of the car into a single whole - the main requirements for it follow - strength and rigidity. Strength is understood as the ability of the supporting system to perceive operational loads without breakdowns of the system as a whole or its elements, and by rigidity, the ability to maintain its shape without residual deformations and without unacceptable elastic deformations under the influence of the same loads.

In terms of the strength properties of the supporting system, fatigue strength is of greatest importance, since it determines the service life of the system, and often of the entire car, up to the stipulated by the regulatory documents for the car. overhaul or write-off. Thus, the fatigue strength (durability) of the bearing system should be sufficient to ensure the overhaul or complete mileage of the vehicle, but it should not be too high, since this would mean that during design, the elements of the bearing system have an extra margin of safety. , excess material, which would affect the increased mass that would have to be transported during the entire life of the vehicle.

The static strength of the supporting system, its ability to perceive one-time operational loads without breakdowns and residual deformations, of course, should be sufficient, but at the same time, with standard dynamic effects on the car simulating accidents (for example, a head-on collision), the supporting system must be deformed in such a way as to absorb impact energy and reduce dynamic loads to the values \u200b\u200bspecified in regulatory documents. From this point of view, the deformation of the supporting system and the associated deformation of the body should be as large as possible, but at the same time, a volume ("survival space") should be maintained inside the body, sufficient for the driver and passengers to be injured to the least extent and had the greatest chances of saving life.

In terms of rigidity, the requirements for the supporting systems of trucks and cars are significantly different.

The rigidity of the body of a passenger car, car or bus should be as large as possible so that the body can confidently resist bends and distortions.

The load-bearing system of a truck, which is usually played by the frame, has different requirements. If the flexural rigidity of the frame, i.e. the ability to withstand bending loads in the vertical and horizontal plane must be sufficiently large, then the torsional stiffness, i.e. the ability to withstand twisting loads when driving, for example, on a road with large irregularities, on the contrary, should not be unnecessary. Of course, there are design possibilities to obtain a high torsional rigidity of the frame, but this entails a significant weighting of the structure as a whole, since high mechanical stresses and, accordingly, breakdowns would arise in its rigid nodes. A relatively torsionally flexible frame is deformed without the appearance of large stresses in its nodes. Aggregates and units are attached to the truck frame, and in some cases, frame deformation could cause unwanted loads in the housings of these units. To avoid this, the units are resiliently secured, and they are secured at three points. In this case, frame distortions cannot cause corresponding distortions of the units. In this way, it is attached to the frame of a truck, for example, a cab or an engine with a gearbox. It was mentioned above that the durability of the support system must match the durability of the vehicle as a whole. In the manufacture of parts included in the supporting system, low-carbon steel is most often used, which is easily stamped and welded. But steel is prone to corrosion. The body of a car, for example, is usually out of order precisely due to corrosion damage. To increase the durability of the carrier system, a coating is provided with various protective compounds that protect the metal from moisture and salt. In some cases, galvanized metal is used for the manufacture of the base of the bodies of passenger cars or the assembled body is subjected to zinc-forging. Consequently, one of the requirements for the support system is its sufficient resistance to environmental influences.

Thus, the requirements for the supporting system are in many respects contradictory and require a high level of engineering skill in its design. When developing the structure of the supporting system and determining its estimated durability when a vehicle is moving on various roads, methods of modeling stresses in structural elements are used.

The main part of the bike is the frame. It not only connects all other parts of the bike, but also directly affects the ride comfort and fit of the cyclist. In addition, it depends on her in what conditions it will be possible to use the model you like.

Materials for making bicycle frames

For the production of modern bicycle frames are used:

In the manufacture of bicycle frames, manufacturers often combine the listed materials with each other. For example, combinations of aluminum with carbon (steel) or titanium with carbon are used.

Bike frame weight

Depending on the type of bike, its cost and purpose, the weight of a bicycle frame can vary from a few hundred grams to several kilograms. For example, an 18-19-inch design used in a typical mountain hardtail, made from chrome-molybdenum steel will weigh 2-2.5 kg, from aluminum alloy - 1.4-1.7 kg, from titanium - 1.4-1 , 7 kg, made of carbon fiber - from 0.9 kg.

Bike frame geometry

The defining parameters of the structures are:

• Rostovka. The size of the frame should be selected taking into account the height of the person, the ratio of the length of the legs and the body, and the riding style.
• ETT is the length of the frame that the rider will feel. If the frame is too long, the person will be forced to "flatten" on it, if too short, the cyclist can reach the handlebars with his knees when cornering.

Types of bicycle frames

Depending on the purpose of the bike and the conditions of its operation bicycle frames are divided into the following main types:

1. Off-road:

• The hardtail is a mountain bike frame with no rear shock. It is possible to install a rack and mounts for flasks.
• Softlane is a frame designed for off-road driving. It copes well with uneven road surfaces, but is not suitable for jumping.
• Full suspension - frame with rear shock absorber. It is impossible to install a trunk on it.
• Mountain tandem. This frame is designed to fit wide rubber and a front suspension fork.

1. Road:

In addition to the listed main types, there are also special frames designed for various extreme disciplines: recumbents, trial.

Depending on the gender of the cyclist, the frames are divided into:

• male,
• female.

The main difference between the designs for women is the lowered upper tube, which is located at a short distance from the lower tube. Some ladies' models have no top tube at all. Due to the absence of an upper triangle, the rigidity of this design is lower than that of the male counterpart. This type of frame was designed so that ladies can ride their "iron friend" in skirts or dresses. In our time, the choice of a female design is determined only by the convenience and habits of a particular cyclist.

The frame is the most languid and metal-consuming unit of the car. For example, the weight of a truck frame can be about 10-15% of its dry weight. The frame vehicle is designed to work in tough conditions. Its frame absorbs all the bumps in the road surface, accepts torsional loads, withstands the weight of the car and must keep its shape in the event of elevation changes.

With all this, the car frame must meet a number of requirements: to be light, strong, have the highest manufacturability in production and repair to reduce costs. Also, the frame must have a long service life, surpassing such a rock in the units installed on it. The hardness and strength of the car frame must ensure that the location of the fixed units remains unchanged. This condition must be met at all vehicle positions and at all speeds.

The frame device must be technologically advanced in production and possible repairs, short time intervals, the greatest mechanization, and low labor costs must be ensured. Convenience of maintenance during repair and modernization, the possibility of introducing modern technologically advanced methods of repair and restoration should be ensured.

Frame construction

All trucks, off-road vehicles, some buses, trailers, semi-trailers have a frame. The most widespread are spar frames. Spinal ones are used less. The spars are divided into ladder, X-shaped, transverse, with X-shaped crossbars.

Ladder frames are used in most cases for trucks, buses, trailers. They are ordinary in design, quite sturdy and undemanding to maintain.

This design contains two longitudinal beams, which are called spars. The spars are connected by transverse bridges. The section in the middle of the side members is larger than on the sides. This allows you to achieve sufficient strength, lower the center of mass of the car, and get easier access when installing the suspension. In most cases, such designs are used on two-axle trucks.

Three-axle cars have a similar frame thickness in the middle and rear. This is due to the high loads on the rear of the vehicle frame.

Specifically, the car parts are usually strengthened to the side members. This is a box, suspension parts, body. The crossmembers give the frame even greater rigidity. Manufactured from low-carbon steel by stamping. Attached to the crossbars optional equipment, some parts of the motor.

Cross members are fastened to the side members, more often by rivets or welding. Bolted connections are not used due to the possible loosening of the bolts during vibration. Welding is used for trailers and semi-trailers. Such a frame is more rigid, in comparison with a riveted one, the welding places give unnecessary stress. Also, the welded frame is the least comfortable to repair.

Tow hooks and a buffer are installed in the front part of the frame, which allows you to protect the car body in case of light impacts and collisions. A drawbar is usually attached to the rear of the frame.

Ladder frame

The ladder frame device has tapering spars at the front and widening at the rear. This design allows you to increase the angle of rotation of the car. The expansion in the rear part makes it possible to install a large body, builds up the rear wheel track, and prevents the car from tilting sideways.

Ladder frame with bending spars in a vertical plane is generally used on frame SUVs... The X-shaped frame has a tubular support at the front. It contains a cardan transmission. The crossmembers are located at the front and rear. The body is mounted in the middle of the vehicle frame. Such a tapering frame allows to increase the angle of rotation of the wheels, has a tremendous strength for twisting and twisting, this is achieved by the use of forked cross members and an average longitudinal support.

Spar frame

The next frame that we see is the spar with X-shaped cross members. Two parallel spars are interconnected by crossing cross members. When twisted, such a structure has a very great hardness and resistance to torsion. The complexity of the production and maintenance of such a car frame makes it possible to use it only on certain types of cars and trailers for a specific purpose.

Peripheral frame

The design of such a frame is very ordinary - these are closed-type side members. Such a frame has a free middle part and in most cases is used on passenger cars frame vehicles... This type of frame creates an additional protective barrier for the vehicle. The free middle part allows to lower the bottom of the car and thus increase its stability. The device of the car frame of this type involves the bending of the side members in the vertical plane to increase the angle of rotation of the wheels.

Heavy-duty trucks use rolling spars and cross members. Low carbon low alloy steel is used. It is stronger than sheet metal (which is used for stamped side members). The mass of such a structure is greater than that of stamping, because the mass of the frame is about 15% of the dry mass of the car, which requires an increase in the power of the power plant.

Spine frame

The most uncommon design is the backbone. There are detachable and one-piece. For passenger cars, one-piece frames are used, for large-scale trucks, split frames.

The introduction of crankcases of gearbox devices as load-bearing parts of a split backbone frame allows to reduce its weight by 15-20% and reduce its metal consumption.

Use a backbone frame for all-wheel drive trucks. The design of such a frame can withstand enormous torsional loads than spar frames.