A frame is a rigid element of a car that takes on the main loads and is used to mount on it the rest of the elements represented by the transmission, body and various equipment. Unlike the carrier body alternative to it, the frame in most cases is flat and is a kind of “rod” 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 - thanks to this, it becomes much easier to manufacture and maintain compared to other types of layout. 
There are many types of frames used in the automotive industry. The most common at present is a straight spar frame, which is created from two longitudinal metal beams running along the entire length of the body. In certain places, they are connected by crossbars - the so-called traverses, which give this element rigidity and are intended for fastening individual units. A special modification of the spar frame is the peripheral design, which implies a significant increase in the distance between the longitudinal spars in the central part of the body. Such frame ones have a fairly low-lying floor, which is located between the beams that play the role of thresholds.
There are also exotic options - in particular, spinal 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 own drawback - the complexity of transport repair, for which it is necessary to completely disassemble the car.
Video about how the frame design of an SUV is arranged:
It is also necessary to mention the lattice frames used in - they create not only a supporting base, but also a safety cage, on which light body panels are hung. Sometimes the frame structure of the car is combined with a load-bearing body - in this case, they talk about an integrated frame that takes on only part of the load. According to the type of connection of frame parts, they are divided into the following types:
- Riveted - easy to manufacture.
- Bolted - have increased strength, but very high labor intensity of assembly.
- Welded - and durable.
Key Benefits
If you look at the list of frame cars of the passenger type, you can see that most of it belongs to large SUVs, such as Toyota Land Cruiser, Nissan Patrol, and others. This is not surprising - after all, the frame can carry heavy loads compared to a load-bearing body. Due to this, better 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. That is why most commercial vehicles are built on the basis of a rigid frame.
UAZ Patriot - representative of frame cars
From the point of view of manufacturers, the frame is also more preferable - it is easier to attach the main units and attachments to it. 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. 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 a ready-to-use load-bearing body. Nevertheless, the majority abandoned the frame structure - therefore, there were reasons for this.
Cons of a hard base
Even the use of modern materials is not able to significantly lighten the frame or reduce its dimensions - it will still make the car heavier and force it to be given large dimensions without a significant increase in the usable volume inside the body. Consequently, emissions of exhaust gases increase and significant environmental damage occurs. On the scale of a narrow segment of SUVs, this is not very important, and if most passenger cars have a similar layout, all the advantages of a car's frame structure pale in front of such problems. In addition, the increase in weight means an increase in the load on the 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 a frame, there is no indestructible connection between it and the rest of the body. Accordingly, when a very strong impact occurs, mutual displacement of various parts of the vehicle occurs. This leads to very serious consequences, in particular, injuries to passengers or even death. Therefore, the main reason for most manufacturers to abandon the frame is the changing requirements for a modern car, which must be as safe and economical as possible.
Who needs a frame?
Knowing what a “frame car” means, we can easily conclude the purpose of such vehicles. They are suitable for use as commercial vehicles, as well as special vehicles designed for very heavy work. In addition, the frame is also necessary for an SUV, which is not designed to overcome urban curbs. If you definitely don’t need such cars, you should pay closer attention to modern cars with a monocoque body. They offer greater fuel efficiency as well as safety and practicality.
By that time, mass models began to appear in many brands, the production of which was sought to be made cheaper and simplified, among other things, by reducing the consumption of materials and simplifying the assembly technology. The then widespread designs with a frame chassis and bodies on a wooden frame did not have this, and, despite the higher price of steel, the body building was reoriented from wood to metal.
Bodies began to cook from stamped metal parts. The designers, who had at their disposal the technology of stamping frame parts of the desired profile and strength, had only to strengthen the spatial structure of the body to the extent that it could carry the components and assemblies of the entire car.
By that time, the calculation methods and metalworking technologies had reached the level when it became possible to achieve a low weight and sufficient rigidity of a three-dimensional system in mass production.
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Lancia Lambda Torpedo 4 Series 1922-1924
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Opel Olympia 1935-1937
So, in fact, the load-bearing body of the car was born. The first frameless mass-produced cars were the Italian Lancia Lambda (1922) with an open "torpedo" body. Then there were the compact sedan Opel Olympia (1935) and the front-wheel drive Citroen 7 Traction Avante (1934), which later became legendary. They showed that a frame for a mass passenger car is not at all necessary. But these cars were akin to today's Tesla or BMW i8. Everyone knew about them, but very few had them.
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fracture
By the middle of the twentieth century, there was another significant advantage of an all-metal load-bearing body over a frame structure. The public began to care about the passive safety of vehicles. Crash tests have shown that cars with a spar frame are dangerous in the most common collisions - frontal ones.
A too rigid frame did not allow the “front end” of the car to deform and absorb the impact energy to the right extent, as a result, passengers in the cabin received fatal injuries from hitting interior parts.
With a frameless car, it turned out to be much easier to calculate the deformation zones for the most "popular" types of collisions and ensure the safety of the "inhabited capsule". The load-bearing body also allowed the designers, with its significant collapse from a frontal impact, to direct a heavy power unit under the bottom, and not into the passenger compartment, as often happened with a frame structure closed from below with rigid spars.
Thus, a whole complex of reasons was formed that led to a departure from the widespread use of frame structures:
1. The emergence of technologies for the production of load-bearing bodies of small mass and sufficient rigidity;
2. The struggle to lighten cars;
3. The desire to increase the usable volume of the body;
4. Desire to improve vehicle handling by lowering the center of gravity;
5. Increasing requirements for the passive safety of the car.
Nash car 1942. Body reinforcements are highlighted in the figure.
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Ford Crown Victoria police interceptor
For these reasons, frame structures lasted in the American auto industry until 2011, when the factory that produced the last of the full-size Mohicans, the Ford Crown Victoria, which we all know from American action movies of the 1990s and 2000s, was closed as the main police transport.
The car was durable, hardy and comfortable, although by today's standards, with significant dimensions (5.4 x 2.0 x 1.5 m), it could not boast of the corresponding space in the cabin. The next police officer Ford - the Taurus Police Interceptor sedan (we wrote about it in an article about) - is already made according to an all-supporting scheme.
What about off road?
Things were not so simple in the off-road car community: it turned out to be more difficult to deprive them of a frame without significant losses. At least because driving on bad roads or off-road one way or another involves frequent "hanging out" of the car - its diagonal skew.
In order to ensure the preservation of the geometry of the load-bearing body, it is necessary to significantly strengthen it with additional scarves, struts, and more powerful beams. Otherwise, distortions of openings with the inability to open or close the door, and even fatigue cracks in the most loaded places are inevitable. The situation is aggravated by the fact that most SUVs have large five-door bodies, which are even more difficult to provide spatial rigidity.
In general, the designers could not completely "pick up" the frame from large SUVs - they made it integrated. In other words, the lightweight parts of the conventional frame were built into the power frame of the body. First of all, these were longitudinal spars, developed to a three-dimensional shape in certain "regions" of the body. So did the creators of the third generation Land Rover Discovery (2004) or Suzuki Grand Vitara (2005) of the second generation.
Suzuki Grand Vitara and Land Rover Discovery
And he was one of the pioneers of the integrated frame among uncompromising SUVs. At birth in 1966, "Volynyanka" received a light open body, in the bottom of which a spar frame of longitudinal and transverse beams was welded. We have already written in detail about the history of this amazing car.
It should be noted that losing the frame, representatives of the glorious tribe of harsh "rogues" risk losing the opportunity to have many close "relatives" - a certain number of variations of bodies and models. After all, it is the frame chassis that facilitates the creation of "
) SUVs are characterized by a frame body structure. Do you know what it is? And how, let's say, is the body on the frame different from the body of an ordinary ordinary car? If not, then today's article is for you...
As usual, let's start with a definition.
- the structure of the car, in which all important technical components and elements are mounted on a specific rigid frame. Such elements include - suspension parts, engine, transmission, axles (front and rear) and the body itself (it is also attached to the frame).
In simple words, the frame is here as a key connecting element of all nodes (if you want as a human skeleton), it also takes on the entire load when driving a car. If the body is not put on the frame, and all the main nodes are fixed on it, then it can easily move. For example, this is how it is implemented on our UAZ.
What is the frame structure of the body for?
The body frame is usually the most durable element, a car with such a structure can withstand heavy loads (both in terms of carrying capacity and in cross-country ability). That is why this body structure is mainly used by "heavy" SUVs, trucks, minibuses and some large buses. SUVs need a frame in order to overcome very bad roads, high hills and swampy terrain. Trucks and buses - for greater carrying capacity.
Body frame device
To exaggerate, the structure is simple to disgrace. Two longitudinal metal beams that are connected by transverse ones. Usually there are only two longitudinal beams, but there can be much more transverse beams. Previously, the longitudinal beams ran almost parallel to each other, but it soon became clear that such a structure was not very convenient, because the engine that was fixed on the frame was set very high. Therefore, later the front part was expanded (so that the engine was mounted between the longitudinal beams), and the rear part was narrowed, especially in the buildings of trucks (also the rigidity of the frame increases, and the load capacity increases accordingly).
It should be noted that the frame is the heaviest part of the body, about 20% of the total mass of the car. But developers are struggling with lighter and stronger materials, because the smaller the mass, the lower the fuel consumption.
By the manufacture of the frame can be divided into:
- ON riveted (the most common type), frame elements are attached to each other with rivets
- ON bolts, more labor-intensive, and therefore less common. Elements are connected with bolts and nuts
— Welded frame, the rarest type. Mainly used for heavy special. technology. The elements are welded to each other.
The main types of body frames
There are several main types:
"Ladder" or spar. As the name implies, it looks like an ordinary staircase. There are no weak points here, all the elements are very durable, so these types are installed mainly on commercial vehicles. Watch an example video
Peripheral or "body". The front and rear are narrow, but the center section (which is under a large part of the body) is widened. This is done in order to lower the body into this part, thereby making the car much lower, which favorably affects aerodynamics.
Spinal. The strengthened central part of a frame, is a transmission pipe. The main application is in cars where independent suspension is both front and rear. Very strong in torsion, but rarely used due to the complex structure and difficult repairs.
"Racing", lattice or tubular. It is not only a frame, but also an almost complete car frame, built from thin (but strong and light) pipes. They are used on sports cars (hence the name), probably everyone has seen the binding of sports cars, this is precisely the frame sports body structure.
Advantages and disadvantages
Well, in conclusion, let's talk about the pros and cons of the body frame structure
1) Most frames are of simple design
2) Easy repair
3) Easy assembly (especially if assembled with rivets)
4) Improved vehicle cross-country ability
5) Improved load capacity
1) Due to the fact that the frame and body are separated, the mass of the car increases
2) Less space in the cabin. Due to the fact that the body is installed between the longitudinal rails
3) The car on the frame is much stiffer. As a rule, the suspension is used with the use of springs, and rarely springs. Because the springs can carry a lot of weight.
4) Difficult landing. Cars are high, if there are no steps, it is not easy to climb.
5) Worse passive safety. The body just rips off the frame with a strong impact.
As you can see, the frame body of the car was created mainly for difficult road conditions, or for transporting large loads. For ordinary comfortable movement around the city, the “frame” is not suitable, it is better to look in the direction of a car with a monocoque body, but this is a completely different story.
Now a small video of the body frame assembly, see for a better understanding.
That's all, read our AUTOBLOG
Greetings, my dear readers! In this publication, friends, we will understand the design features of car bodies, their varieties and find out what is better than a frame or a load-bearing body.
If you're the owner of a classic SUV built to tackle the toughest obstacles, then you'll understand why it has a frame. Of course, this article will be of interest to those who want to deepen their knowledge about cars, who want to start from the basics - from their frame, skeleton.
To begin with, in general terms, we denote that there is a frame. In its simplest form, these are two parallel metal beams (spars), interconnected by a plurality of crossbars.
A suspension with wheels is attached to this structure, an engine is installed, and then a body is hung from above. And nothing prevents developers from hanging different bodies on the same frame - this is one of its advantages.
The frame as the basis of a vehicle has appeared since the very beginning of automotive technology and has been actively used in this role for many decades. What is the reason for this longevity?
The point is the banal imperfection of technology, due to which other variants of the skeletons, for example, load-bearing bodies, were heavier and more difficult to manufacture. But time passed, new alloys appeared, conveyors improved and safety requirements increased.
All these factors pushed the frame frames in the passenger car segment into the background, giving way to load-bearing frames. In fairness, it must be said that the frames are not completely forgotten. On their basis, highly passable SUVs and trucks are still being created, because where there are high loads, such car frame structures have advantages.
Evolution and diversity of frames
And yet, what is better a frame or a load-bearing body ... If about frames, then frames are quite diverse in their execution. There are such types:
- spars;
- spinal;
- spatial.
The spar frame is a fairly simple and popular design. Two parallel spars with crossbars providing rigidity, which can be located both in the same plane and change their profile. This type of frame frame is used today in the production of trucks, as well as SUVs.
spinal frame
The spinal view is less popular, one might even say that it is now a rarity. The basis of such a core is one beam located in the middle, and crossbars are attached to it, like ribs. One of the features of the spinal frames is the suspension, which in this case can only be performed according to an independent scheme. The main carrier of such a frame were Tatra trucks.
Spatial or frame frames
What can unite buses and sports cars? As it turned out - spatial frames. These frames, more like load-bearing bodies, are like a 3D model of a car, but without body panels.
Frame and load-bearing bodies: confrontation
Well, friends, it remains for us to find out why, despite their simplicity, frame frames have given way under the sun to load-bearing bodies.
One of the main reasons was their low passive safety - when developing a car with a frame frame, it is almost impossible to create so-called deformation zones. In addition, the body itself, where the driver and passengers are located, is more vulnerable, and if we start to strengthen it with different elements, we will end up with a very heavy car, which is also unacceptable in modern realities.
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The bearing part is one of the most important components in the device of the car, because it is thanks to it that it is possible to assemble all the components of the car 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 there is no frame, 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 frame of the car is a beam structure, which acts as the basis for fastening all the components of the car - the power plant, transmission units, chassis and other things. The body, present in the design of the bearing 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 thanks to this that it is used on trucks and full-fledged SUVs. But at the same time, because of the frame, the total mass of the car is increased.
Also, the frame of the car allows you to unify the nodes and mechanisms between models of different classes to the maximum. At one time, it came to the point that many automakers produced a car chassis with all the main parts (frames, engines, transmissions, chassis), on which different types of bodies were “stretched”.
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:
- Spar
- Spinal
- Spatial
Some of these types have subspecies, and 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 crossbars.
Spar frame Toyota Land Cruiser
The spars themselves are made of steel, and to ensure high torsional performance, different types of section profile are used - a box, an I-beam, a channel.
Moreover, it is not necessary that they be even, many spars have bends in both the vertical and horizontal planes. For example, on some cars, the frame is curved in the front and rear parts (in the area where the wheels are located), which allows you to move the center of gravity down.
In addition, the spars 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 spars are connected by crossbars, which can be located in different ways. In the so-called ladder-type frame, the crossbars are attached perpendicular to the spars (considered classic). But there are also designs in which these components are located at angles - K-shaped and X-shaped frames.
Spar x-shaped frame
To connect the spars with the crossbars, welding is used (in off-road vehicles), rivets (trucks). In some cases, bolted connections are used. For fastening the nodes of the car, both the side members and the cross members are equipped with brackets.
A subspecies of the spar frame is peripheral. Its distinctive feature is the large distance between the spars. After the car is fully assembled, they are located near the body sills, which significantly increases the resistance to side impacts, and also allows you to lower the floor level (as far as possible).
Corvette Peripheral Frame
Another type of spar frame is the X-shaped. The essence of the design of such a frame is that the spars are separated in the front and rear parts, and in the central part they are reduced to the maximum (the space between them allows only the transmission shafts to be placed). Outwardly, this type resembles the letter "X", hence the name.
Another option is a supporting base. The design of this frame still uses longitudinal spars, but here they are interconnected not by crossbars, but by the bottom. At the same time, the supporting base, although the bottom is included in it, is not an element of the body, therefore this type belongs to the frames.
load-bearing base
spinal frame
Backbone-type frames are less common and, in fact, they are used only on Tatra trucks. The main component of this type of bearing part is a central beam made of a pipe.
spinal frame
It is noteworthy that in such a frame, some auto components are used as load-bearing elements, namely the engine, gearbox, final drive 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 drive axles is that the transmission of rotation to the wheels is carried out by shafts with cardan joints, and not by axle 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 include 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 main gears and connect them using the central beam.
But this car frame was not widely used due to the complexity of servicing and repairing transmission units, since for this it is necessary to disassemble almost the entire frame in order to disconnect the main gear housings and the gearbox. In addition, the body, fixed on the pipe, is located quite high above the ground. Therefore, this type of frame is only suitable for use on trucks.
space frame
Spatial is the frame of the car, presented in the form of a frame welded from pipes. Differs in the small weight and high rates on durability.
This frame forms not only compartments for placing and fixing 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 home-made models - buggies. It is noteworthy that even on mass cars with a monocoque body, which are remade for participation in competitions, they are equipped with an internal tubular frame to increase body rigidity. But in this case, the installed frame cannot be called a full-fledged spatial frame.
Combined views
The main types of frame bearing parts are listed above. But, as noted, there are many variations that are combined types.
These include a fork frame. In this type, there are the main components of the spar and spinal types - the central beam and spars. The design looks like this: in the front and rear parts, longitudinal spars are used to fasten the auto components, and a pipe is installed in the central part (but here it is not used to accommodate drive shafts). The beam and spars are rigidly connected to each other.
fork frame - symbiosis of several species, 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 side members (unlike a forked one, the side members are located only in front).
But there are also options that combine different types of load-bearing part - a frame and a load-bearing body. This type includes the so-called integrated frame. Its essence boils down to the fact that the elements of the frame (spar classical or peripheral) are included in the body structure and are made integral with it (they are rigidly connected to each other). But it is worth noting that the spars are usually located only in the front and are designed to fix the power plant.
Integrated frame with body
Another option for combined load-bearing parts is a body with a subframe. This element performs the same functions as the side members in the integrated version, but unlike 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. In almost any passenger car, you can find reinforcing spars or subframes.