) 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 all the 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 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 strong, so these types are installed mainly on cargo commercial transport. 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 vehicles where independent suspension both front and back. 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.

Pros and cons

Well, in conclusion, let's talk about the pros and cons frame structure body

1) Most frames are of simple design

2) Easy repair

3) Easy Assembly(especially if assembled on 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

car frame

The frame serves as a base on which all parts and mechanisms of the car and its body are fixed.

All trucks have a frame. The frame consists of two longitudinal beams - spars, connected by several cross members - traverses. The spars are made by stamping from sheet steel and have a trough or box-shaped section of a variable profile, most reinforced in the middle part. Parts of the frame are fastened with charcoal and kerchiefs on rivets or by welding.

Rice. 1. Truck frame

The front transverse beams serve to mount the engine. Brackets for attaching suspension parts are attached to the spars.

For trucks, in the rear part of the frame, a towing device is installed on special transverse beams, including a hook with a lock and a shock-absorbing spring or with a rubber shock absorber. The hook is intended for connection of the trailers towed by the car.

Two simple hooks are attached to the front of the frame, used for towing the car in case of malfunction, pulling it out of the mud, etc.

A metal buffer is attached to the front of the frame. The frame with all the parts assembled on it rests through the suspension parts on axles with wheels.

The frame is also equipped with large-capacity passenger cars with a significant distance between the axles of the wheels ("Seagull", ZIL -111).

Rice. 2. Bearing car body

To obtain the necessary strength and eliminate the possibility of body deformations, the frame of cars is made of a special design, usually with an X-shaped transverse beam and beams with enlarged sections. Buffers are attached to the front and rear of the frame.

For passenger cars of small and medium capacity, a separate frame is usually absent and a rigid body base is used instead of a frame. Such a body is called a carrier. Cars "Zaporozhets", "Moskvich" and "Volga" have a load-bearing body structure.

For a passenger car with a load-bearing body, the frame is replaced by a rigid body frame structure (Fig. 2), consisting of a floor reinforced with beams, a front part, side pillars, a roof and a rear part. These parts are equipped with amplifiers and connected by welding. In the front part, a short (sub-engine) frame is attached to the floor of the body with bolts or by welding, which serves to install the power unit and the front suspension of the car. Struts welded to the frame are bolted or welded to the body shield.

The frame of the car serves to mount the engine, chassis units, bodywork on it and, thus, is a load-bearing structure.

Rice. 3. Spar frame of the car ZIL -130: 1 - towing hook; 2 - buffer; 3 - shock absorber bracket; 4 - cross member; 5 - spar; 6 - towing device; 7 - spring brackets; c - engine mount bracket

All trucks, high class cars and some types of buses have a frame. By design, frames are spar, central (spinal) and X-shaped (combined).

The spar frame, which has received the greatest distribution, consists of two spars (longitudinal beams), interconnected by several crossbars (Fig. 3). A buffer with two towing hooks is attached to the front end of the frame, and a towing device is installed in the rear of the frame. Brackets for shock absorbers, springs, engine mounts, cabs and platforms are attached to the spars.

Spars and crossbars are stamped from sheet steel and connected to each other with rivets. The cross section of the spars has a trough-shaped profile with the greatest height and rigidity in the middle, more loaded part of the frame. The crossbars may have a special shape required for the installation of certain components and assemblies of the vehicle.

The frameless design of the car provides for the use of a load-bearing body and is used in cars small, middle class and some types of buses. This allows to reduce the weight of a passenger car by about 5%, a bus - by 15%. The car body is a rigid welded structure, including a floor reinforced with spars and crossbars, a front end with two side members of the sub-frame, a rear part with a panel, sidewalls with uprights, fenders and a roof.

The frame of the car during movement experiences significant vertical dynamic loads from the forces of inertia of the sprung parts - the frame itself, the engine, the clutch and gearbox, and the body. The frame is calculated for bending and torsion strength and is made of low carbon or low alloy steels with good strength and ductility.

The frame of the car is a skeleton on which all the mechanisms of the car are fixed. The frame must have high strength and rigidity, but at the same time be light and shaped in such a way that a lower center of gravity of the car is possible to increase its stability.

There are three main types of frames:
- spars, consisting of two longitudinal beams (spars), connected by crossbars;
- central, having one longitudinal beam or pipe as a ridge;
- combined, combining both principles in their design (the middle part of the frame is performed as a central one, and the ends are made spar).

On trucks, the most common are spar frames, consisting of two longitudinal parallel beams - spars connected by cross members (traverses), using welding or rivets. In areas subjected to the greatest loads, the spars have a higher profile, and are sometimes reinforced with local inserts. The material for the spars are steel trough-shaped profiles (channels). The spars are sometimes made curved in the vertical and horizontal planes.

Rice. 3. Automobile frames: a and b - spar; c - central; g - combined

Brackets are riveted or screwed to the spars for attaching springs, steps and a spare wheel, as well as a buffer and towing device. The buffers protect the body from damage during collisions, and the towing device is used to tow trailers.

The frame is the basis for mounting units, mechanisms and car body.

The truck frame consists of two longitudinal beams - spars, and several cross members. The frame elements are made by stamping and connected with each other by rivets. The spars along the length have an unequal cross section; in the middle part, and three-axle vehicles and in the back, they are of great height. The crossbars are made in such a shape that provides fastening to the frame of the corresponding mechanisms.

In front of the frame, a buffer and towing hooks are attached to the spars. ZIL cars on the front buffer have a reclining footrest. A towing device and removable elastic buffers are installed on the rear cross member. On ZIL vehicles, there are two eyebolts on the rear cross member for attaching emergency trailer chains.

The towing device consists of a hook with a latch, a rubber buffer with thrust washers, a body with a bracket and a cap. The hook latch is held in the closed or open positions by a pawl. To eliminate spontaneous disengagement, a cotter pin attached to a hook on a chain is inserted into the holes of the latch and pawl. Lubrication of rubbing surfaces is carried out through a grease fitting. The towing device of the Ural-375D car uses a spring as an elastic element, and the device itself is fixed in a special cross member, which is attached from below to the rear ends of the frame side members.

Rice. 4. Frame car ZIL -131:
1 - front buffer; 2 - towing hook; 3 - starting handle bracket; 4, 9, 12, 13, 14 - crossbars; 5 - mudguard; 6 - bracket for the rear engine mount; 7 - upper shock absorber bracket; .8-- mounting bracket solenoid valve switch-on control front axle; 10 - bracket rear suspension cabins; 11 - mounting bracket transfer box; 15 - trailer chain eye; 16 - towing device; 17 - brackets for rear spring buffers; 18, 20 - front spring brackets; 19 - spar

The main faults of the frame are the weakening of the rivets, the appearance of cracks and kinks in the frame. Loose rivets are detected by the rattling sound they make when tapped with a hammer. Cracks and breaks are determined by external inspection. Loose rivets should be replaced with new ones or bolts with spring washers should be used instead.

Due to the high strength and rigidity of the special frame Maintenance does not require. It is necessary to clean it daily from dirt and dust (snow), to wash it. At TO-1, the condition of the rivet joints and the integrity of individual frame elements are checked. It is necessary to monitor the condition of the frame coloring and timely tint the places where the coloring is broken.

The frame of the car must be of high strength and rigidity. The frame should be light and shaped to allow a lower center of gravity for the vehicle, which increases its stability.

Rice. 5. Frames:
a - with parallel spars; b - with tapering spars; in - with curved spars; 1 - spar; 2 - cross member

Spar frames got their name from the longitudinal beams-spars that form their basis, connected to each other by crossbars by welding or riveting. In places subjected to the greatest loads, the spars have a higher profile, and are sometimes reinforced with local inserts. The spars are often made curved in the vertical and horizontal planes. To protect against damage to the radiator and fenders, buffers in the form of transverse beams are installed at the front end of the frame, which perceive shocks when the car hits an obstacle.

The front cross member of the frame has a shape specially adapted for mounting the engine. To strengthen the crossbars, scarves and squares are sometimes superimposed at the points of their attachment to the spars.

In cars with load-bearing bodies, there is no frame, but there is a subframe for attaching the engine and front wheels to the body.

On fig. 6 shows a frame of a truck, consisting of two side members having a channel profile of variable section, and cross members. Spars and cross members are made of mild steel sheet.

The front buffer and towing hooks are attached to the spars at the front with brackets and bolts.

For fastening the radiator and the front engine mounts, a front cross member riveted to the spars is used. The rear supports for the engine are brackets.

The front springs are attached to the brackets. Rubber buffers prevent the springs from hitting the side member. The rear springs are attached to the brackets. In a loaded car, the ends of the springs (additional springs) rest on the support platforms.

On the left side member there is a socket for batteries and bracket for mounting the crankcase of the steering mechanism. On the right side member there is a bracket 6 for fastening the spare wheel.

The intermediate support of the cardan shaft is reinforced from the bottom of the second cross member, to the upper part of which the rear cab support is attached.

The towing device is attached with a spacer and braces to the rear cross member. A turn signal bracket is placed at the rear end of the right side member, and a rear light bracket is placed at the rear end of the left side member.

Rice. 6. Frame car ZIL -130:
1 - front buffer; 2 - towing hook mounting bracket; 3 - towing hook; 4 - engine mounting bracket; 5 - spar amplifier; 6 - spare wheel mounting bracket; 7 - bracket for direction indicator; 8 - stretching; 9 - towing device; 10, 13, 16, 17 and 24 - crossbars; 11 - rear light bracket; 12 - spacer for fastening the towing device; 14 - rear spring mounting bracket; 15 - support pads of the sprung; 18 - platform mounting bracket; 19 - spar; 20 - battery socket; 21 - bracket for fastening the crankcase of the steering mechanism; 22 - front spring mounting bracket; 23 - rubber buffer; 25 - bracket for guiding the crank

The brackets serve to secure the platform, and the bracket to guide the crank.

To increase the rigidity and strength of the frame, amplifiers are attached to its spars.

When towing a car, hooks are used.

The frame is the base of the truck and serves to install all units on it. To ensure the correct interaction of the units, the frame must have high rigidity. The frame consists of two longitudinal beams-spars having a channel section, and several transverse beams-traverses. Frame beams are made of flat steel by hot stamping. For the spars, low-alloy steel is used, and for the traverse, carbon steel is used. Along the length, the spars have a variable section - larger in the middle part and smaller at both ends. Brackets of springs, side engine mounts, power steering, etc. are riveted to them.

Category: - Vehicle Chassis

Frame (car)

car frame Land Rover III. 2008

For cars with a load-bearing body, either the body itself performs the functions of the frame (skin with local reinforcement), or the frame (or subframes replacing it) is structurally integrated with the body and cannot be separated from it without violating structural integrity (the latter option is sometimes distinguished into a separate type of car with integrated frame). To a separate frame, the body is usually attached using bolted brackets with thick rubber gaskets that serve to reduce the level of vibration affecting the driver and passengers.

As a rule, all the main units of the car are attached to the frame - engine, transmission, axles, suspensions, steering. Together they form chassis. The frame chassis is a complete structure, which, as a rule, can exist and move separately from the body.

At present, frame chassis are used mainly on tractors and trucks, but in the past, many passenger cars also had a frame chassis. Also, “hard” SUVs often have a separate frame.

In the automotive industry, the following types of frames are distinguished: spar, peripheral, spinal, fork-spinal, load-bearing base, lattice(they are tubular, spatial).

Story

Frames appeared at the dawn of development automotive technology. A separate frame was a purely automotive solution for the carrier system, and the idea was borrowed from railway transport, since horse-drawn carriages managed with a wooden body frame due to significantly lower loads.

Initially, the frames were made of hard wood, less often - round metal pipes.

In the first decade of the 20th century, frames made of stamped rectangular sections became widespread; on trucks, their design has changed only in details to this day.

In 1915, H. J. Hayes proposed load-bearing body acting as a frame. This idea was put into practice much later. In subsequent years, load-bearing bodies are becoming more common, and before the Second World War, they were already quite familiar. They became massive in the post-war period.

In the twenties, the Czechoslovak company Tatra developed a spinal frame, applying it to a number of passenger and truck models. However, this scheme did not receive wide distribution outside the Czechoslovak automobile industry (the only mass example of its use “in its pure form” without any reservations was the Volkswagen Beetle, but its design was partially copied just from the developments of the Tatra, which in the post-war years was confirmed during the trial).

During the same time period, the first space frame bodies appeared, the first example being the 1922 Lancia Lambda (sometimes considered the first monocoque car, but rather it had a tubular space frame). The developers were inspired by the design of boat hulls.

Almost simultaneously, a spar frame with an X-shaped cross member was created at Auburn in the USA, combining high torsional rigidity and relative lightness.

The monocoque body of a 1942 Nash car.

In the thirties in Europe, more and more car manufacturers abandon the frame, using a self-supporting body on their structures - but these were not yet load-bearing bodies in the full sense of the word: at the ends, their supporting structure was nevertheless formed subframes- a kind of short spar frame, welded or, more often, bolted to the body.

Some European cars of those years, for example, the pre-war Ford Prefect or KIM-10, had a very lightweight frame, which, although it was physically separated from the body, did not in itself have sufficient rigidity to absorb the loads arising from the movement of the car, doing this only when assembled with a semi-supporting body ; such a frame served to facilitate the assembly of the car at the factory - on the conveyor, first all the units were attached to the frame, and then it was already attached to the body in the assembled form.

However, in the United States of those years, as before, most manufacturers continue to produce cars with a frame chassis, largely due to the tradition of annual design updates: when restyling, they changed the body, but the frame could remain practically unchanged for many years. The American company Nash, on the contrary, switched to load-bearing bodies, but this ruined it: Nash did not keep up with the accelerated pace of design updates set by market leaders model range, since in the case of a load-bearing body this was a very difficult and costly task.

After the Second World War, in Europe, new passenger models are built mainly with load-bearing bodies, while in America, most manufacturers remain committed to separate frames. By design, they were generally similar to pre-war ones - in most cases a type with a powerful X-shaped central crossbar was used - with the exception of the changes necessary to install an independent front suspension (which became the de facto standard on post-war passenger cars) and some reduction in the height of the spars relative to land to facilitate getting in and out of the car.

By the 1948 model year, the American firm Hudson (Hudson Motor Car Company) creates a line of models step-down("Step down"), which have powerful thresholds of an all-welded monocoque body, which had a commercial designation Monobilt, on the sides covered the passenger compartment, the floor of which was attached to them from below. Entering such a car, a person carried his leg over a high threshold, first raising it to his level, and then lowering it a dozen centimeters to the floor level (this is where the “step down” comes from); for those years, this was very unusual, since in cars with a separate spar frame, the floor of the passenger compartment was located directly above its spars, flush with the thresholds. The Hudsons at this level had only the cross members of the power set of the body, located under the seats and not interfering with the placement of passengers in the cabin. The lower location of the floor of the passenger compartment made it possible to lower both the seats and the roof by the same ten centimeters; the car turned out to be very squat for those years, visually more dynamic and streamlined, and the arrangement of passengers - more rational. They no longer entered such a body, like a carriage or a bus, but sat down. When driving on rough roads, passengers were less swayed, and roll in corners decreased, since the center of gravity of the car was located lower. In terms of handling, the Hudson had no equal among American full-size cars until the mid-fifties. Finally, powerful thresholds located on the sides of the passenger compartment well protected the driver and passengers in a side collision.

During the first few years of its release, the Hudsons were commercially quite successful cars. However, over time, competitors introduced models with an improved configuration of a separate frame, which approached them in terms of performance, but had a more modern design that could be varied every year without serious investment without changing the carrier frame, while any serious modification of the carrier The body of the Hudson affected its supporting structures and required, in fact, a complete redesign, which was a very difficult task before the advent of computers and CAD. As a result, already in the second half of the fifties, the Hudson company left the stage, unable to withstand the pace of renewal of the lineup set by competitors.

A more rational solution at that time turned out to be a load-bearing body used in pre-war models, in which the load-bearing structure is represented by subframes at the ends, and the outer skin panels perform a predominantly decorative function and are bolted, not welded. Characteristic in this regard can be considered the design of the load-bearing elements of the body domestic cars"Pobeda" GAZ-M-20 and "Volga" GAZ-21: although their body was considered self-supporting, at its ends there were full-fledged spar subframes in the form of box-shaped profiles, and the front subframe was structurally detachable and, in fact, was a short one, going up to the middle of the car, the frame (and that is exactly what it was called in the factory documentation). The rear subframe was already welded to the saloon floor and luggage compartment and was not structurally separated, but in design it still repeated the back of a conventional spar frame.

At the turn of the fifties and sixties, some firms tried to experiment with lighter backbone and X-shaped frames; for example, in the USSR, the Chaika GAZ-13 of 1959 had an X-shaped frame, and in America - full-size models of the late fifties - the first half of the sixties. But the bulk of cars with a frame chassis retained spar frames, as a rule - with an X-shaped cross member, like in pre-war cars, which predetermined the relatively high location of the floor of the passenger compartment and the center of gravity.

The mass distribution of peripheral frames in the United States falls on the mid-sixties, which coincides with a massive decrease in the height of passenger cars to a reasonable limit of 1300 ... 1400 mm. The passenger compartment, located completely between the frame spars, made it possible to give the body beautiful proportions without sacrificing space. In terms of space efficiency and rationality of passenger accommodation, cars with a peripheral frame were only slightly inferior to a carrier body, while the possibility of annual restyling without affecting the carrier structures, the comparative cheapness of car assembly, and simplicity body repair and other advantages of a separate frame. In addition, the widely spaced spars in the central part made it possible to significantly improve passive safety in a side impact: in a conventional car with a ladder spar frame, only relatively weak and thin external body sills protect passengers from the side. (rocker panels), while a car with a peripheral frame has powerful spars that play the same role as the boxes (internal thresholds) of the load-bearing body. For the same purpose of increasing passive safety in the early seventies, elements of programmed deformation began to be introduced into the design of American car frames; for example, on Ford vehicles an S-shaped deformable element appeared in the front of the frame, which absorbs kinetic energy upon impact.

The brands owned Chrysler Corporation, in the same period, they switched to load-bearing bodies with a long separate subframe in the front, attached to the body in the manner of a separate frame - through thick rubber gaskets.

The frames of passenger cars and SUVs have remained practically unchanged since the mid-sixties and seventies to the present, only production technology has been improved (for example, on latest models the frame is made by stamping with elastic media - “hydroforming”), as well as passive safety elements embedded in the frame design (programmed deformation zones, stronger body mounts, and so on). However, since then their prevalence has decreased significantly: if back in the late seventies the bulk of American cars, except for "compacts" (compact cars) and "subcompacts" (sub-compact cars), had frames separate from the body - these days it is mainly the lot of large pickups and SUVs, as well as rare passenger car models that structurally date back to the seventies - for example, Ford Crown Victoria and Lincoln Continental.

The load-bearing body, on the contrary, was waiting for a long evolutionary process. In the late fifties and sixties, load-bearing bodies appeared, in which there were no subframes, and the loads were already perceived exclusively by the inner skin of the body (mainly the floor and mudguards of the wings), which had various amplifiers in the most loaded places, and also, to a certain extent, its outer sheathing. For example, in the body of the Zhiguli and their Italian prototype Fiat 124, subframes in the form of fragments of a spar frame are structurally absent as such, and the power structure of the front end is formed by the lower parts of the mudguards of the front wings, to which amplifiers in the form of U-shaped profiles are welded from the inside, along with them forming a closed box-shaped section and, thus, from a functional point of view, playing the role of front spars, on which the front suspension beam is attached from below, which also works as a cross member of the body's power set. The front fenders and the front bumper apron in the body of the Zhiguli, which form the outer skin of the front end, are welded to the mudguards, and along with them perceive some of the load that occurs when the car is moving. Thus, this type of load-bearing body is a semi-monocoque - a monolithic rigid structure, in which the skin itself takes the main load, and the frame is maximally reduced, lightened and cannot be physically separated from the skin. This made it possible to further lighten the body while increasing its rigidity, increase its manufacturability and reduce the cost of production, although the design began to require a higher production culture, was more difficult to repair and less durable when operating on bad roads.

Although load-bearing bodies with separate subframes had certain advantages in terms of driving comfort (if there were rubber gaskets between the body and subframe), as well as ease and convenience of repair, nevertheless, the considerations of manufacturability of mass production and ensuring maximum rigidity turned out to be more significant, therefore bodies of modern cars are mainly representatives of this particular branch of development.

Modern load-bearing bodies are complex structures welded or glued from steel - often made of high-strength alloy steels - or aluminum stampings and designed for the most efficient absorption of energy during deformation during a traffic accident, while formed by the casing of the cavity-box, coupled with additional reinforcement with U-shaped overlays, tubular elements, filling with special polymer foam, and so on - form a powerful "safety cage" around the passenger compartment that protects the driver and passengers. The term "subframe" in relation to a modern body designates no longer a load-bearing element of its design, but only a lightweight frame attached to the load-bearing body from below, on which, for the convenience of conveyor assembly of a car, parts of the front and rear suspension, engine, transmission are pre-mounted. Modern load-bearing bodies, as a rule, are not designed for restoration repairs after serious impacts, since outside the factory conditions it is impossible to ensure compliance with the geometry of the body and reproduce the technological measures laid down at the stage of its production, aimed at increasing the passive safety of the car.

Design

A distinctive design feature of any frame is the separation of the functions of the load-bearing (power, perceiving workloads) elements of the body and its decorative panels. At the same time, the decorative panels themselves can also have their own reinforcing frame, for example, in the area of ​​​​door openings, but it practically does not participate in the perception of loads that occur when the car is moving. Frames are classified according to the type of supporting structure they use.

Spar frames

Spar frame with X-shaped cross member.

The classic version of such a frame resembles a ladder in appearance and design, so in everyday life it can sometimes be called staircase(ladder frame). Spar frames consist of two longitudinal spars and several cross members, also called "traverses", as well as mounts and brackets for mounting the body and units. The shape and design of the spars and crossbars can be different; so, there are tubular, K-shaped and X-shaped crossbars. Spars usually have a channel section, and usually variable in length - in the most loaded areas, the section height is often increased. Sometimes they have a closed section (box) at least for part of their length. On sports cars, tubular spars and round cross-sections could be used, which had a better ratio of mass and stiffness. By location, the spars can be parallel to each other, or located relative to each other at a certain angle. Frame parts are connected by rivets, bolts or welding. Trucks usually have riveted frames, light and super-heavy dump trucks - welded. Bolted connections are usually used in small-scale production. Modern heavy trucks also sometimes have bolt-on frames, making them much easier to maintain and repair.

The spar frame usually has a small height and is located almost entirely under the floor of the body, and the latter is attached to its brackets from above through rubber cushions.

Spar frames are used on almost all trucks, in the past they were widely used on cars - in Europe until the end of the forties, and in America - until the end of the eighties - mid-nineties. On SUVs, spar frames are widely used to this day. In view of such a wide distribution, usually in popular literature, the word "frame" is understood to mean exactly the spar frame.

A number of sources also include peripheral (often distinguished as a separate type) and X-shaped frames to spar (the latter are classified by other sources as a kind of spinal).

Peripheral frames

An inverted Mercury station wagon, a peripheral frame is visible with spars widely spaced in the central part.

Sometimes considered as a type of spar. In such a frame, the distance between the spars in the central part is increased so much that when the body is installed, they are directly behind the door thresholds. Because weak points of such a frame are the places of transition from the usual distance between the spars to the increased one, in these places special box-shaped reinforcements are added, in English-speaking countries called by the term torque box(similar power elements - braces - are often available on cars with a load-bearing body at the transition points from the front and rear spars to the boxes).

This solution allows you to significantly lower the floor of the body, placing it completely between the spars, and therefore reduce the overall height of the car. Therefore, peripheral frames (English Perimeter Frame) have been widely used on American passenger cars since the 1960s. In addition, the location of the spars directly behind the thresholds of the body is very conducive to improving the safety of the car in a side collision. This type of frame was used on high-end Soviet ZIL cars starting from the .

Spinal frames

Spinal frame of the Tatra truck.

This type of frame was developed by the Czechoslovak company Tatra in the twenties and is a characteristic design feature of most of its cars.

The main structural element of such a frame is the central transmission pipe, which rigidly connects the crankcases of the engine and power transmission units - clutch, gearbox, transfer case, main gear (or main gears - on multi-axle vehicles), inside which there is a thin shaft that replaces the cardan shaft in this design . When using such a frame, an independent suspension of all wheels is required, usually implemented in the form of two swinging axle shafts attached to the ridge on the sides with one hinge on each.

The advantage of such a scheme is very high torsional rigidity, in addition, it makes it easy to create modifications to cars with a different number of drive axles. However, the repair of the units enclosed in the frame is extremely difficult. Therefore, this type of frame is used very rarely, usually on off-road trucks with a large number of drive axles, and on cars it has completely fallen into disuse.

Fork-spine frames

The frame of the pre-war "Skoda" with a sub-fork in the front.

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

Unlike the backbone frame, as a rule (but not always) the crankcases of the power transmission units are made separately, and, if necessary, a conventional cardan shaft. Such a frame had, among others, executive cars "Tatra" T77 and T87.

X-shaped frames are often referred to the same type, which are considered by other sources as a type of spar. Their spars in the central part are very close to each other and form a closed tubular profile. Such a frame was used on the Soviet cars "Chaika" GAZ-13 and GAZ-14 of the highest class, as well as many full-size cars General Motors late fifties - first half of the sixties.

load-bearing base

In this design, the frame is integrated with the floor of the body to increase rigidity.

Among others, Volkswagen Beetle had such a design (however, its frame, due to the presence of a massive central tube, is closer to the forked spinal one) and the LAZ-695 bus. Currently, this scheme is considered quite promising due to the ability to build a variety of cars on the same bearing base as on a platform.

lattice

Also called tubular(tubular frame) or spatial(space frame).

Lattice frames are an iso-truss of relatively thin tubes, often made of high-strength alloy steels, which have a very high torsional stiffness-to-weight ratio (i.e., they are light and yet very torsionally stiff).

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

The main difference between a body with a space frame and a load-bearing body is that its skin is purely decorative, often made of plastic or light alloys, and does not participate in the perception of the load at all. On the other hand, the load-bearing body can be considered as a kind of spatial frame, where the skin takes almost the entire load, and the frame itself, represented by U-shaped and box-shaped reinforcements of the skin, is lightened and reduced to the limit.

Body-integrated frame (Frame-in-body, UniFrame)

Such a frame repeats the usual design, but is physically inseparable from the body, that is, it has a non-separable welded connection with it.

It differs from a conventional load-bearing body with an integrated frame in that the first one has, as a maximum, only subframes at the ends, and the integrated frame has real spars going from the front bumper to the rear. Such a body does not have many advantages of a separate frame - vibration damping, ease of body repair, ease of creating modifications with various types of bodies on a single frame, and others, but sometimes it turns out to be somewhat more convenient and cheaper to manufacture than a load-bearing body, and also perceives loads better, arising from the transportation of goods and off-road driving. This determines the range of use of such a design in modern automotive industry - mainly pickups and SUVs (except for "hard").

; however, due to the characteristics of this type of load-bearing structure, the lattice frame body usually either has no doors at all or has very high sills, which makes it unsuitable for general purpose vehicles.

Another thing is that, for example, a truck or an all-terrain vehicle, unlike a road car, often does not need a large torsional rigidity of the body; moreover, the limited ability of a flat spar frame to deform under the action of twisting forces often improves patency, which was observed in particular on ZIS-5 and GAZ-AA trucks, whose riveted frame could deform with an amplitude of up to several centimeters when twisting, which is equivalent to an increase in suspension travel. Unimog cars also have a twisting frame, and the deformation of the frame to improve cross-country ability was built into the design from the very beginning;

Sources and notes

A self-propelled four-wheeled vehicle with an engine designed to transport small groups of people on roads. A passenger car, usually accommodating from one to six passengers, is precisely what distinguishes it in the first place ... ... Collier Encyclopedia

- (from Auto ... and lat. mobilis moving) means of trackless transport with its own engine. History reference. Even in the Middle Ages, attempts were made to create carts that were supposed to move by the power of the wind or ... Great Soviet Encyclopedia

Automobile- (Cars) Contents Contents 1. The history of the creation of the first car 2. The history of brands Aston Martin Bentley Bugatti Cadillac Chevrolet Dodge Division Ferrari Ford Jaguar 3. Classification By purpose By size By body type By displacement ... ... Investor Encyclopedia Wikipedia

- ... Wikipedia

Long-term studies have shown that during the movement of the car, uncontrolled forces act on the body, proportional to the mass of the car at the moment and its speed, which act in three directions - vertical, horizontal and frontal - and cause such types of deformation of the body elements as bending, compression, twisting. The task of the repair work is to restore the designed endurance of the body components according to the manufacturer's instructions. The technology of repair work must be such that the endurance of the repaired parts corresponds to the non-repaired parts of the car.

For cars with a load-bearing body, the functions of the frame are either performed by the body itself, or the frame (or subframes replacing it) are structurally integrated with the body and cannot be separated from it without violating structural integrity. Typically, the body is attached to the frame using bolt-on brackets with thick rubber pads to reduce vibration.

All units are attached to the frame of the car: 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.

At present, frame chassis are used mainly on tractors and trucks, but in the past, many passenger cars also had a frame chassis. “Rigid” SUVs often have a separate frame.

The following types of frames are distinguished: spar, peripheral, spinal, forked-spinal, bearing base, lattice (they are also tubular).

Spar frame with X-shaped crossbar

Spar frames consist of two longitudinal spars and several crossbars, called "traverses", as well as mounts and brackets for mounting the body and units.

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

Peripheral frames

Sometimes considered as a kind of spar. In such a frame, the distance between the spars in the central part is increased so much that when the body is installed, they are directly behind the door thresholds. Since the frame is weakened at the transition points from the usual distance between the spars to the increased one, special box-shaped reinforcements are added in such places, in English-speaking countries called the term torque box.

This solution allows you to significantly lower the floor of the body, placing it completely between the spars, and therefore reduce the overall height of the car. Therefore, peripheral frames have been widely used on American passenger cars since the sixties. In addition, the location of the spars directly behind the thresholds of the body is very conducive to improving the safety of the car in a side impact.

Spinal frames

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

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

Fork-spine frames

A kind of spinal frame, in which the front, sometimes the rear parts are forks formed by two spars and used to mount the engine and units.

Unlike the backbone frame, the crankcases of the power transmission units are usually (but not always) made separately, if necessary, it uses a conventional cardan shaft. Such a frame was used, among others, by Tatra executive cars from T77 to T613.

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

load-bearing base

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

Among others, the Volkswagen Beetle and the LAZ-695 bus had such a design. Currently, this scheme is considered quite promising due to the ability to build a variety of cars on the same bearing base, like on a platform.

lattice

Also called tubular (tubular frame) or spatial (spaceframe).

Lattice frames are in the form of an iso-truss having a very high torsional rigidity-to-weight ratio (i.e., they are light and very torsional-strength).

Such frames are used either on sports and racing cars, for which low weight is important with high strength, 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 its design features. For example, consider the frontal deformation of the front of the car at an angle, in which the front panel, hood, fender, mudguard and side member are deformed. Of these, in this node, 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, passenger safety while driving, etc.).

Therefore, if we accept the repair of the mudguard and fender, then the hood, radiator frame and spars must be replaced. When replacing the hood, it is possible to control the repaired surface of the wing at the junction with the hood, control the location of the radiator frame when replacing it, and adjoin the repaired mudguard to it. When replacing the radiator frame, it is possible to control the geometry of the hood opening, the correct adjoining 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 taken into account that, conditionally, repairs without heating and welding will be applied to the wing and mudguard. If heating is applied to one of the repaired elements to shrink the metal or weld 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, however, a decision is made to repair the spar assembly, that is, the U-shaped spar itself with slight heating, then the amplifier must be replaced when editing, be it a separate amplifier, which is an amplifier mudguard or other element.

It must also be remembered that although the manufacturer designed the structural endurance of body elements for a safety factor n = 1.3–1.5, and for the edges of the body, which are subject to the combined action of turbulent forces formed by the gearbox and wheels during movement, the safety factor is even 1.5–2.0, without proper equipment, technological maps and load distribution diagrams during an accident, we cannot determine how the repair factor will affect the safety of passengers during 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 non-repaired ones, ideal option repair of this unit will be the replacement of all elements that cannot be repaired without the use of heating or welding of technological cuts.

An example of a spar repair on frame car

The right spar under the floor of the passenger seat is affected by through corrosion to such an extent that the brackets of the front axle levers are not only unable to perform their functions, but also come off.

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

In order to securely place the support under the threshold, it had to be replaced, as well as partially replace the floor.

After that, the front axle levers are removed, the damaged part of the side member is cut out and replaced. The work is not easy, because the load distribution cutouts 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 a floor reinforcement, on which an overlay is welded, welded to the side member.

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

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

If the result of a collision with a car is a significant deformation, it is first necessary to remove the mechanical units - this is the only way to carefully straighten the folds and replace parts that cannot be repaired. In addition, this will remove residual stresses that may arise and remain after straightening. When the car is moving, residual stresses can cause stresses in the mountings of shock absorbers and bushings, and sometimes breaks.

But in some cases, pre-straightening the body with installed mechanical units can facilitate access to the units to be removed, for example, to the propulsion unit in cars with front-wheel drive, 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 on the stand.

If a blow to the front or rear half-axle caused deformation of the base of the body, it is also possible to straighten the body by fixing (hooking) the stretching mechanism for mechanical units, such as wheel rims or suspension arms that have received deformation. Editing is done in the direction directly opposite to the impact. Performing such an operation is possible only if the blow fell directly on the front or rear half-axle, and its replacement is necessary.

It also needs to be replaced ball joints and steering rods. Straightening with a jack or other hydraulic mechanism is used to restore the shape or straighten a deformed part. However, when starting work, one should not forget that with a very sharp editing of a body part, deformation of the neighboring 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 out the folds. And after drawing out with a jack, it is necessary to remove all internal stresses by tapping (using a straightening hammer) the entire area that has been straightened.

In order to be sure that there will not subsequently be a reverse movement of the straightened sections of the body due to residual stresses, the surface is tapped through the wooden lining in the direction of impact. If at the same time the straightened body does not change its shape, then the editing operation was performed correctly. Otherwise, you should edit again until the geometry is within the tolerances specified by the vehicle manufacturer.

If the car has received a side impact, this 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 determine. When editing on 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 the restoration of the side surface is the alignment of the middle rack, which is wrapped 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, fixing the clamps to the flanging of the thresholds. 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 in the upper part of the body, stretching is carried out in the longitudinal direction from the front and rear parts of the body.

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

In any case, geometry diagnostics are best done on good equipment, the choice of which will be discussed in the next issue.

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

The bearing part is one of critical 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 that acts as the basis for attaching all the components of the car - power plant, transmission units, chassis and other. 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.

Main positive quality the use of the frame is a high indicator of the 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:

1. Spar
2. Spinal
3. 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 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 cases 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 load-bearing part - frame and 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.