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Automobile site - Behind the wheel

» Types and purpose of car suspension. Car suspension The chassis of the car consists of

Types and purpose of car suspension. Car suspension The chassis of the car consists of

The road along which the driver chooses a route is not always level and smooth. Very often, it may contain such phenomena as uneven surfaces - cracks in the asphalt and even bumps and potholes. Don't forget about speed bumps. This negative would have a negative impact on driving comfort if there were no shock-absorbing system - the car's suspension.

Purpose and device

While driving, road unevenness in the form of vibrations is transmitted to the body. The vehicle's suspension is designed to dampen or soften such vibrations. Its application functions include providing communication and connection between the body and the wheels. It is the suspension parts that give the wheels the ability to move independently of the body, allowing the vehicle to change direction. Along with the wheels, it is an essential element of the car's chassis.

A car suspension is a technically complex unit that has the following structure:

  1. elastic elements - metal (springs, springs, torsion bars) and non-metallic (pneumatic, hydropneumatic, rubber) parts, which, due to their elastic characteristics, take the load from road unevenness and distribute it to the car body;
  2. damping devices (shock absorbers) - units that have a hydraulic, pneumatic or hydropneumatic structure and are designed to level body vibrations received from an elastic element;
  3. guide elements - various parts in the form of levers (transverse, longitudinal) that provide connection between the suspension and the body and determine the movement of the wheels and body relative to each other;
  4. anti-roll bar - an elastic metal rod that connects the suspension to the body and prevents the car from increasing roll while driving;
  5. wheel supports - special steering knuckles (on the front axle), which absorb the loads coming from the wheels and distribute them over the entire suspension;
  6. fastening elements for parts, components and assemblies of the suspension are means of connecting suspension elements with the body and among themselves: rigid bolted connections; composite silent blocks; ball joints (or ball joints).

Principle of operation

The operation of a car's suspension is based on the conversion of the impact energy arising from a wheel hitting an uneven road surface into the movement of elastic elements (for example, springs). In turn, the rigidity of the movement of elastic elements is controlled, accompanied and softened by the action of damping devices (for example, shock absorbers). As a result, thanks to the suspension, the impact force that is transmitted to the car body is reduced. This ensures smooth running. The best way to see the system in action is to use a video that clearly demonstrates all the elements of a car's suspension and how they interact.

Cars have suspensions of varying stiffness. The stiffer the suspension, the more informative and efficient the car control. However, this seriously compromises comfort. And, on the contrary, the soft suspension is designed in such a way that it provides ease of use and sacrifices controllability (which cannot be allowed). That is why car manufacturers are striving to find their best option - a combination of safety and comfort.

Variety of suspension options

The vehicle suspension device is an independent design solution of the manufacturer. There are several typologies of car suspension: they are distinguished by the criterion underlying the gradation.

Depending on the design of the guide elements, the most common types of suspension are distinguished: independent, dependent and semi-independent.

The dependent version cannot exist without one part - a rigid beam that is part of the car axle. In this case, the wheels move parallel in the transverse plane. The simplicity and efficiency of the design ensures its high reliability, preventing wheel alignment. That is why dependent suspension is actively used in trucks and on the rear axle of cars.

The independent suspension system of a car assumes that the wheels exist autonomously from each other. This improves the damping characteristics of the suspension and ensures a smoother ride. This option is actively used for organizing both front and rear suspension on passenger cars.

The semi-independent version consists of a rigid beam secured to the body using torsion bars. This scheme ensures relative independence of the suspension from the body. Its typical representative is the front-wheel drive VAZ models.

The second typology of suspensions is based on the design of the damping device. Experts distinguish hydraulic (oil), pneumatic (gas), hydropneumatic (gas-oil) devices.

The so-called active suspension stands apart. Its design includes variable capabilities - changing suspension parameters using a specialized electronic control system depending on the vehicle's driving conditions.

The most common parameters to change are:

  • degree of damping of the damping device (shock absorber);
  • degree of rigidity of the elastic element (for example, a spring);
  • degree of rigidity of the anti-roll bar;
  • length of guide elements (levers).

Active suspension is an electronic-mechanical system that significantly increases the cost of the car.

Main types of independent suspension

In modern passenger cars, an independent suspension option is often used as a shock-absorbing system. This is due to the good controllability of the car (due to its low weight) and the absence of the need for total control over the trajectory of its movement (as, for example, in the case of a truck).
Experts distinguish the following main types of independent suspension. (By the way, the photo will allow you to more clearly analyze their differences).

Double wishbone suspension

The structure of this type of suspension includes two levers attached to the body with silent blocks, and a coaxially located shock absorber and coil spring.

MacPherson strut suspension

This is a derivative (from the previous type) and a simplified version of the suspension, in which the upper arm was replaced by a shock absorber strut. Currently, MacPherson strut is the most common front suspension design for passenger cars.

Multi-link suspension

Another derivative, improved version of the suspension, in which two wishbones were “separated” as if artificially. In addition, the modern version of the suspension very often consists of trailing arms. By the way, multi-link suspension is the most commonly used rear suspension design for passenger cars today.

The design of this type of suspension is based on a special elastic part (torsion bar), which connects the lever and the body and works to twist. This type of design is actively used in organizing the front suspension of some SUVs.

Front suspension adjustment

An important component of a comfortable ride is the correct adjustment of the front suspension. These are the so-called steering wheel alignment angles. In common parlance, this phenomenon is called “wheel alignment”.

The fact is that the front (steered) wheels are installed not strictly parallel to the longitudinal axis of the body and not strictly perpendicular to the road surface, but with certain angles that provide tilts in the horizontal and vertical planes.


Correctly set wheel alignment:

  • firstly, it creates the least resistance to vehicle movement, and, therefore, simplifies the process of driving;
  • secondly, it significantly reduces tire tread wear; thirdly, it significantly reduces fuel consumption.

Installing corners is a technically complex procedure that requires professional equipment and work skills. Therefore, it should be performed in a specialized institution - a car service or service station. It’s hardly worth trying to do this yourself using a video or photo from the Internet if you have no experience in such matters.

Suspension faults and maintenance

Let’s make a reservation right away: according to Russian legal norms, not a single suspension malfunction is included in the “List of…” malfunctions with which driving is prohibited. And this is a controversial point.

Let's imagine that the suspension shock absorber (front or rear) does not work. This phenomenon means that driving over every bump will be associated with the prospect of body rocking and loss of vehicle controllability. What can we say about the completely loose and unusable ball joint of the front suspension? The result of a malfunction of a part - “the ball has flown out” - threatens a serious accident. A broken elastic suspension element (most often a spring) leads to body roll and sometimes an absolute inability to continue moving.

The malfunctions described above are the final, most odious malfunctions of the car suspension. But, despite their extremely negative impact on traffic safety, operating a vehicle with such problems is not prohibited.

Monitoring the condition of the vehicle while driving plays an important role in suspension maintenance. Creaks, noises and knocks in the suspension should alert and convince the driver of the need for service. And long-term operation of the car will force it to use a radical method - “change the suspension all around,” that is, replace almost all the parts of both the front and rear suspension.

Without the chassis, the car simply would not be able to move, since the power plant, along with the transmission and drive, would simply have nowhere to transmit torque.

The chassis of the car includes wheels, which perceive this torque, rotate and move the car. However, this is not the main task of the chassis. The car does not move on a perfectly flat surface; there are always bends, protrusions, potholes, holes, etc. on the road.

If the wheels were attached to the car body or frame without suspension - the second component of the chassis, then there would be no need to talk about comfort - almost all irregularities would be immediately transmitted to the body, only slightly lowered by the pneumatic tire of the wheel. So the chassis not only drives the car, but also provides comfort by reducing oscillatory movements from the wheel to the body.

Suspension that reduces oscillatory movements began to be used even before the appearance of the car itself. Some carriages were equipped with elements made of springy sheet steel. These elements consisted of two steel arcs, hingedly connected to each other. The upper arc was attached to the carriage itself, and the lower one to the axle of the wheels. When moving, these springy arches were partially absorbed from the wheel axis. The suspension of the carriage became the prototype of the dependent suspension of the car.

The essence of the suspension itself is the ability to vertically move the wheel relative to the body or frame when driving over uneven surfaces. Thanks to the suspension elements, the impact that the wheel receives from the road surface is not transmitted to the body, but is absorbed. That is, the wheel mount in the car is not rigid relative to the body.

Dependent suspension. Types, design features

In total, two types of suspension are used on vehicles - dependent and independent. At the moment, this type of suspension, such as dependent, is considered somewhat outdated, but it is still used quite widely on trucks, full-size frame SUVs and ordinary passenger cars. Dependent suspension has received such application in transport due to the simplicity and reliability of the design.

Spring suspension

The main element of this pendant is. It consists of a package of spring steel sheets, slightly bent into an arc. Moreover, this package often has a pyramidal shape. The ends of the spring are attached to the car frame, and the axle is attached to its central part. Each car uses two springs, installed closer to the wheels. These springs, thanks to the springy steel, absorb road unevenness, allowing the wheel to move relative to the body.

Rear dependent suspension of a front-wheel drive car

However, this also has a negative quality - the work of the spring is accompanied by inertial oscillatory movements. That is, when the spring perceives unevenness in the road, it receives energy, which leads to its oscillatory movements. And although over time the amplitude of the vibrations will decrease until it fades, they will be transmitted to the frame. The car will sway even on a smooth road after passing a bump.

To significantly reduce the oscillation time of the spring, shock absorbers are included in the suspension design, which absorb oscillatory energy. To put it simply, the shock absorber stops the spring after an unevenness, preventing it from rocking the car.

Spring suspension

There is another type of dependent suspension - spring. This suspension uses coil springs instead of springs. They are more convenient to use because they have significantly smaller dimensions.

Video: Car chassis

But there are also some nuances here. If the spring itself acted as a fastening element connecting the frame to the wheel axle, then the spring cannot act in such a capacity. Therefore, the design of the spring suspension includes a system of rods and levers that pivotally connect the body to the axle (beam, bridge).

A spring, like a spring, also receives inertial oscillatory movements as a result of the impact on it, so such a suspension could not do without the use of shock absorbers.

There were other types of dependent suspension, for example, but they were not widely used in vehicles.

The main disadvantage of a dependent suspension is the partial transfer of the movement of one wheel relative to the body to the second. The wheels are fixed to the axle, and it transmits these movements. Therefore, dependent suspension is not very suitable for installation on a steered axle.

But it is still widely used on the rear axle, both driving and driven. On frame SUVs of the latest generations, spring suspension is still found. Spring suspension is often used on passenger front-wheel drive cars. Moreover, the technical characteristics of a car do not always indicate that the rear suspension is dependent; it is often called a spring-loaded beam.

Independent suspension. Device, features

Independent suspension

The second type of suspension is independent, characterized by the fact that each wheel of the axle has its own fastening and vibration damping system, which does not transfer the movement of one wheel to the other. In fact, in an independent suspension there is no wheel axle (beam, bridge) as such.

The most widely used type is the “McPherson” type. The design of such a suspension is quite simple - the wheel hub is hinged to the car body using levers. The types of these levers and their location may vary. There are A-arms, single, double, lower and upper. The simplest independent suspension consists of one lower control arm.

MacPherson strut suspension

Additionally, the hub is attached to the body with a shock absorber strut, which also acts as a steering knuckle. The main elements of this strut are a coil spring and a shock absorber. The strut itself is a housing in which the shock absorber is placed, and a spring is located on top of the strut.

At the top the rack rests against the body. There is a stand cushion installed between them, on which it rests. A thrust bearing installed inside allows the rack to rotate around its axis. This makes it possible to turn the wheel.

No matter how well the shock absorber strut works, there is the possibility of transmitting vibrations to the body. This may result in lateral sway of the body. To prevent this from happening, the design includes an anti-roll bar that connects both wheel suspensions. By working in torsion, this stabilizer dampens lateral vibrations.

These are the main elements of an independent suspension. But there are also a large number of auxiliary elements that you cannot do without. Such an element, for example, is the counter cushion. These also include all rubber elements:

  • silent blocks;
  • ball joints;
  • bushings.

All of them are also involved in damping vibrations. Silent blocks, ball joints and bushings are placed wherever the suspension elements are connected - arms with the body and hub, anti-roll bar with hubs and subframe, etc.

Basic malfunctions and diagnostics of the suspension

Since the suspension, no matter what it is - dependent or independent, moves the wheels relative to the body and dampens all vibrations, it experiences significant loads, leading to failure of one or another element.

In dependent suspension, the most common malfunctions are loss of shock absorber performance due to oil leakage and physical damage. It is also often necessary to change all the rubber elements that are also present in this type of suspension. Over time, the rubber component “aging” occurs - it shrinks and begins to delaminate. It is quite possible that the springs or springs may be destroyed; due to significant loads, they may burst.

In the independent suspension the faults are the same:

  • wear of rubber elements and ball joints;
  • shock absorber release;
  • destruction of the spring or anti-roll bar.

Therefore, you need to constantly monitor the suspension, promptly replace consumables, and monitor the condition of shock absorbers, springs and springs.

Car owners often do not carefully select a service center for repairs or routine inspection of the car. But in vain. After all, a master is a kind of doctor for a vehicle. One wrong step or an incorrectly established “diagnosis” - and the car will go into a long “coma”. And this will lead to even greater costs and inconvenience. You should be especially whimsical when repairing a running car. Without this unit, the car would not be able to move, since the power unit, together with the transmission and drive, would not be able to transmit torque.

Still looking for a reliable service station? Then we recommend that you pay attention to the car repair service in Moscow “Autoclinica” - http://www.autoclinica.ru/. Here, first-class craftsmen will take care of your car at the highest level. No overpayments or incorrect “diagnoses”. You will be informed about the details of the problem and suggested a method to solve the problem. All breakdowns are repaired quickly and efficiently.

The chassis is a connecting chain that goes from the wheels to the body itself. This unit of the car takes on all the road bumps along the way. If the chassis is properly adjusted, the driver of the car may not feel discomfort at all when driving, even when driving off-road. Therefore, to fully operate the car, you should know the basic characteristics of the unit and at least its basic structure. In this article we will tell you what you should pay special attention to.

What does the chassis of the car consist of?

The design includes the following elements:

  • wheels;
  • fixation bridge;
  • frame or body;
  • suspension system (or suspension).

In general, the chassis can be supplemented with other components. But the elements presented above are considered the main ones. They are responsible for comfort and ease of control. Any of these components performs its function, but in tandem they provide:

  • reduction of vibration when driving;
  • regulation of vibrations in the cabin;
  • reduction of car shaking when moving.

Every detail must be lined up correctly. This is the only way to achieve ideal results. And repair of the car chassis, as in the link - http://www.autoclinica.ru/page/Remon-hodovoy.html, will occur much less frequently.

Characteristics of the dependent suspension of the machine

This type of design, on the one hand, is considered obsolete, but is still used quite widely. This is especially true for trucks, full-size SUVs, as well as ordinary passenger cars. In car design, dependent suspension has become widespread due to its simplicity and reliability.

This design is divided into 2 types: spring and spring. In the first type, the main element is a spring, which consists of a complex package of sheets of special spring steel. They are slightly bent into an arc. The lugs are attached to the frame of the machine, and the center is connected to the axle. Vehicles use two springs, which are installed closer to the wheels. They have a springy structure and absorb all imperfections in the road surface.

The operation of the spring suspension is based on the use of coil springs. The design is more convenient, as it has significantly reduced dimensions. This includes a system of traction and levers, which, thanks to the hinges, act as a connecting link between the body and the axle of the car.

Independent car suspension

This type is characterized mainly by the fact that all wheels have a personal fastening and a system for damping various vibrations. In this case, there is no transmission of motion between the four wheels. In fact, independent suspension eliminates the axle.

The most widely used design is the McPherson type. This type of pendant is very simple. The work is based on the fact that the hub is connected to the body using hinges thanks to levers. The types of such levers and location may vary. There are A-shaped structures, single, connected from two parts, lower and upper. The simplest car suspension consists of 1 lower control arm.

Main types of breakdowns

Based on the type of design, certain types of faults are distinguished. In dependent suspensions, the shock absorber often suffers due to oil leakage or mechanical damage. Rubber elements also wear out and springs or springs are destroyed. With independent suspension, the breakdowns are almost the same. With regular use of vehicles with intense loads, the rate of chassis failure increases. Therefore, find a reliable service station in advance.

Let's immediately deal with the topics without delay . Moreover, the topics are quite interesting, although this is the second one in a row about cars. I’m afraid the female readership and pedestrians don’t quite like this, but that’s how it happened. Let’s listen to the topic from :

“How do car suspensions work? Types of pendants? What determines the ride roughness of a car? What is a “hard, soft, elastic ...” suspension?

We'll tell you... about some options (and oh, how many of them actually turn out to be!)

The suspension provides an elastic connection between the car body or frame and the axles or directly with the wheels, softening the shocks and impacts that occur when the wheels hit uneven roads. In this article we will try to consider the most popular types of car suspensions.

1. Independent suspension on two wishbones.

Two fork arms, usually triangular in shape, direct the rolling of the wheel. The swing axis of the levers is parallel to the longitudinal axis of the vehicle. Over time, double-wishbone independent suspension has become standard equipment on cars. At one time, it proved the following indisputable advantages:

Low unsprung weight

Low space requirement

Possibility of adjusting vehicle handling

Available with front-wheel drive

The main advantage of such a suspension is the ability for the designer, by selecting a certain geometry of the levers, to rigidly set all the main setting parameters of the suspension - changing the wheel camber and track during compression and rebound strokes, the height of the longitudinal and transverse roll centers, and so on. In addition, such a suspension is often completely mounted on a cross member attached to the body or frame, and thus represents a separate unit that can be completely removed from the vehicle for repair or replacement.

From the point of view of kinematics and controllability, double wishbones are considered the most optimal and perfect type, which determines the very wide distribution of such suspension on sports and racing cars. In particular, all modern Formula 1 cars have just such a suspension, both front and rear. Most sports cars and executive sedans these days also use this type of suspension on both axles.

Advantages: one of the most optimal suspension schemes and that says it all.

Flaws: layout restrictions associated with the length of the transverse arms (the suspension itself “eats up” quite a large space in the engine or luggage compartments).

2. Independent suspension with oblique arms.

The swing axis is located diagonally with respect to the longitudinal axis of the car and is slightly inclined towards the middle of the car. This type of suspension cannot be installed on cars with front-wheel drive, although it has proven its effectiveness on small and medium-class cars with rear-wheel drive.

TO Mounting wheels on trailing or oblique arms is practically not used in modern cars, but the presence of this type of suspension, for example, in the classic Porsche 911, is definitely a reason for discussion.

Advantages:

Flaws:

3. Independent suspension with swing axle.

The independent swing-axle suspension is based on Rumpler's patent from 1903, which was used by Daimler-Benz until the seventies of the 20th century. The left pipe of the axle shaft is rigidly connected to the main gear housing, and the right pipe has a spring connection.

4. Independent suspension with trailing arms.

The independent suspension with trailing arms was patented by Porsche. TO Mounting wheels on trailing or oblique arms is practically not used in modern cars, but the presence of this type of suspension, for example, in the classic Porsche 911, is definitely a reason for discussion. In contrast to other solutions, the advantage of this type of suspension was that this type of axle was connected to a transverse torsion spring bar, which created more space. The problem, however, was that reactions of strong lateral vibrations of the car occurred, which could lead to loss of controllability, which, for example, is what the Citroen 2 CV model became famous for.

This type of independent suspension is simple, but imperfect. When such a suspension operates, the wheelbase of the car changes within fairly large limits, although the track remains constant. When turning, the wheels tilt together with the body significantly more than in other suspension designs. Oblique arms allow you to partially get rid of the main disadvantages of the suspension on trailing arms, but when the influence of body roll on the inclination of the wheels is reduced, a change in the track appears, which also affects handling and stability.

Advantages: simplicity, low cost, relative compactness.

Flaws: outdated design, extremely far from perfect.

5. Independent suspension with wishbone and spring strut (McPherson strut).

The so-called “McPherson suspension” was patented in 1945. It was a further development of the double wishbone type suspension, in which the upper control arm was replaced with a vertical guide. MacPherson spring struts are designed for use with both front and rear axles. In this case, the wheel hub is connected to a telescopic pipe. The entire rack is connected to the front (steered) wheels via hinges.

McPherson first used the 1948 Ford Vedet model, produced by the French branch of the company, on a production car. It was later used on the Ford Zephyr and Ford Consul, which also claim to be the first large-scale cars with such a suspension, since the Vedette plant in Poissy initially had great difficulty mastering the new model.

In many ways, similar suspensions were developed earlier, right up to the very beginning of the 20th century, in particular, a very similar type was developed by Fiat engineer Guido Fornaca in the mid-twenties - it is believed that McPherson partially took advantage of his developments.

The immediate ancestor of this type of suspension is a type of front suspension on two wishbones of unequal length, in which the spring in a single unit with a shock absorber was placed in the space above the upper arm. This made the suspension more compact, and made it possible to pass an axle shaft with a hinge between the arms on a front-wheel drive car.

Replacing the upper arm with a ball joint and a shock absorber and spring unit located above it with a shock absorber strut with a rotary joint mounted on the mudguard of the wing, McPherson received a compact, structurally simple and cheap suspension named after him, which was soon used on many Ford models. European market.

In the original version of such a suspension, the ball joint was located on the extension of the axis of the shock absorber strut, so the axis of the shock absorber strut was also the axis of rotation of the wheel. Later, for example on the Audi 80 and Volkswagen Passat of the first generations, the ball joint began to be shifted outward towards the wheel, which made it possible to obtain smaller and even negative values ​​of the running-in arm.

This suspension became widespread only in the seventies, when technological problems were finally solved, in particular, the mass production of shock absorber struts with the necessary service life. Due to its manufacturability and low cost, this type of suspension subsequently quickly found very wide application in the automotive industry, despite a number of shortcomings.

In the eighties, there was a tendency towards the widespread use of MacPherson strut suspension, including on large and relatively expensive cars. However, subsequently, the need for further growth in technical and consumer qualities led to a return on many relatively expensive cars to double wishbone suspension, which is more expensive to manufacture, but has better kinematic parameters and increases driving comfort.

The rear suspension is Chapman type - a variant of the MacPherson strut suspension for the rear axle.

McPherson created his suspension for installation on all wheels of the car, both front and rear - in particular, this is how it was used in the Chevrolet Cadet project. However, on the first production models, the suspension of his design was used only in the front, and the rear, for reasons of simplicity and cost reduction, remained traditional, dependent with a rigid drive axle on longitudinal springs.

Only in 1957, Lotus engineer Colin Chapman used a similar suspension for the rear wheels of the Lotus Elite model, which is why in English-speaking countries it is commonly called “Chapman suspension”. But, for example, in Germany such a difference is not made, and the combination “MacPherson rear suspension” is considered quite acceptable.

The most significant advantages of the system are its compactness and low unsprung weight. The MacPherson suspension has become widespread due to its low cost, labor-intensive manufacturing, compactness, and the possibility of further refinement.

6. Independent suspension with two transverse springs.

In 1963, General Motors developed the Corvette with an exceptional suspension solution - an independent suspension with two transverse leaf springs. In the past, coil springs were preferred over leaf springs. Later, in 1985, the first production Corvettes were again equipped with a suspension with transverse springs made of plastic. However, in general, these designs were not successful.

7. Independent spark plug suspension.

This type of suspension was installed on early models, for example, on the Lancia Lambda (1928). In this type of suspension, the wheel, together with the steering knuckle, moves along a vertical guide mounted inside the wheel housing. A coil spring is installed inside or outside this guide. This design, however, does not provide the wheel alignment required for optimal road contact and handling.

WITH The most common type of independent passenger car suspension these days. It is characterized by simplicity, low cost, compactness and relatively good kinematics.

This is a suspension on a guide post and one wishbone, sometimes with an additional trailing arm. The main idea when designing this suspension scheme was not controllability and comfort, but compactness and simplicity. With fairly average performance, multiplied by the need to seriously strengthen the place where the strut is attached to the body and the rather serious problem of road noise transmitted to the body (and a whole bunch of other shortcomings), the suspension turned out to be so technologically advanced and was so liked by the assemblers that it is still used almost everywhere . In fact, only this suspension allows designers to position the power unit transversely. MacPherson strut suspension can be used for both front and rear wheels. However, in English-speaking countries, a similar suspension of the rear wheels is usually called “Chapman suspension”. This pendant is also sometimes called the term “candle pendant” or “swinging candle”. Today, there is a tendency to move from the classic MacPherson strut to a design with an additional upper wishbone (the result is a kind of hybrid of MacPherson strut and wishbone suspension), which allows, while maintaining relative compactness, to seriously improve handling characteristics.

Advantages: simplicity, low cost, small unsprung masses, a good design for various layout solutions in small spaces.

Disadvantages: noise, low reliability, low roll compensation (“dive” during braking and “squat” during acceleration).

8. Dependent suspension.

Dependent suspension is mainly used for the rear axle. It is used as a front suspension on jeeps. This type of suspension was the main one until about the thirties of the 20th century. They also included springs with coil springs. The problems associated with this type of suspension relate to the large mass of unsprung parts, especially for the axles of the drive wheels, as well as the inability to provide optimal wheel alignment angles.

WITH The oldest type of suspension. Its history dates back to carts and carts. Its basic principle is that the wheels of one axle are connected to each other by a rigid beam, most often called a “bridge”.

In most cases, if you do not touch on exotic schemes, the bridge can be mounted either on springs (reliably, but not comfortable, rather mediocre controllability) or on springs and guide arms (only slightly less reliably, but the comfort and controllability becomes much greater) . Used where something really strong is required. After all, nothing stronger than a steel pipe, in which, for example, drive axle shafts are hidden, has been invented yet. It practically never occurs in modern passenger cars, although there are exceptions. Ford Mustang, for example. It is used more often in SUVs and pickups (Jeep Wrangler, Land Rover Defender, Mercedes Benz G-Class, Ford Ranger, Mazda BT-50, etc.), but the trend towards a general transition to independent circuits is visible to the naked eye - controllability and speed are now in greater demand than the “armor-piercing” design.

Advantages: reliability, reliability, reliability and once again reliability, simplicity of design, constant track and ground clearance (on off-road this is a plus, not a minus, as for some reason many believe), long travel, allowing you to overcome serious obstacles.

Flaws: When working off uneven surfaces and in turns, the wheels always move together (they are rigidly connected), which, coupled with high unsprung masses (the axle is heavy - this is an axiom), does not have the best effect on driving stability and controllability.

On a transverse spring

This very simple and cheap type of suspension was widely used in the first decades of automobile development, but as speeds increased, it almost completely fell out of use.
The suspension consisted of a continuous axle beam (driving or non-driving) and a semi-elliptical transverse spring located above it. In the suspension of the drive axle there was a need to accommodate its massive gearbox, so the transverse spring had the shape of a capital letter “L”. To reduce spring compliance, longitudinal reaction rods were used.
This type of suspension is best known for the Ford T and Ford A/GAZ-A cars. This type of suspension was used on Ford vehicles up to and including the 1948 model year. GAZ engineers abandoned it already on the GAZ-M-1 model, created on the basis of the Ford B, but which had a completely redesigned suspension on longitudinal springs. The rejection of this type of suspension on a transverse spring in this case was due to the greatest extent to the fact that, according to the operating experience of the GAZ-A, it had insufficient survivability on domestic roads.

On longitudinal springs

This is the most ancient version of the pendant. In it, the bridge beam is suspended on two longitudinally oriented springs. The axle can be either driven or non-driven, and is located both above the spring (usually on cars) and below it (trucks, buses, SUVs). As a rule, the axle is attached to the spring using metal clamps approximately in its middle (but usually with a slight shift forward).

A spring in its classic form is a package of elastic metal sheets connected by clamps. The sheet on which the spring mounting ears are located is called the main sheet - as a rule, it is made the thickest.
In recent decades, there has been a transition to small or even single-leaf springs, sometimes non-metallic composite materials (carbon fiber reinforced plastic, etc.) are used for them.

With guide arms

There are a variety of designs for such suspensions with different numbers and locations of levers. The five-link dependent suspension shown in the figure with a Panhard rod is often used. Its advantage is that the levers rigidly and predictably set the movement of the drive axle in all directions - vertical, longitudinal and lateral.

More primitive options have fewer levers. If there are only two levers, when the suspension operates they warp, which requires either their own compliance (for example, on some Fiats of the early sixties and English sports cars, the levers in the spring rear suspension were made elastic, plate-like, essentially similar to quarter-elliptical springs) , either a special articulated connection of the arms with the beam, or the flexibility of the beam itself to torsion (the so-called torsion bar suspension with conjugate arms, still widespread on front-wheel drive cars
Both coiled springs and, for example, air cylinders can be used as elastic elements (especially on trucks and buses, as well as lowriders). In the latter case, a strict command of the movement of the suspension guide vane in all directions is required, since pneumatic cylinders are not able to withstand even small transverse and longitudinal loads.

9. Dependent suspension type "De-Dion".

The De Dion-Bouton company in 1896 developed a rear axle design that made it possible to separate the differential housing and the axle. In the De Dion-Bouton suspension design, the torque was perceived by the bottom of the car body, and the drive wheels were mounted on a rigid axle. With this design, the mass of non-damping parts was significantly reduced. This type of suspension was widely used by Alfa Romeo. It goes without saying that such a suspension can only operate on the rear driven axle.

De Dion suspension in a schematic representation: blue - continuous beam suspension, yellow - main gear with differential, red - axle shafts, green - hinges on them, orange - frame or body.

The De Dion suspension can be described as an intermediate type between dependent and independent suspensions. This type of suspension can only be used on drive axles, more precisely, only the drive axle can have the De Dion type of suspension, since it was developed as an alternative to a continuous drive axle and implies the presence of drive wheels on the axle.
In the De Dion suspension, the wheels are connected by a relatively light, one way or another sprung continuous beam, and the main gear reducer is fixedly attached to the frame or body and transmits rotation to the wheels through axle shafts with two hinges on each.
This keeps unsprung mass to a minimum (even compared to many types of independent suspension). Sometimes, to improve this effect, even the brake mechanisms are transferred to the differential, leaving only the wheel hubs and the wheels themselves unsprung.
When operating such a suspension, the length of the axle shafts changes, which forces them to be carried out with joints of equal angular velocities movable in the longitudinal direction (as on front-wheel drive cars). The English Rover 3500 used conventional universal joints, and to compensate, the suspension beam had to be made with a unique sliding joint design, which allowed it to increase or decrease its width by several centimeters when the suspension was compressed and released.
“De Dion” is a technically very advanced type of suspension, and in terms of kinematic parameters it surpasses even many types of independent ones, being inferior to the best of them only on rough roads, and then only in certain indicators. At the same time, its cost is quite high (higher than many types of independent suspension), so it is used relatively rarely, usually on sports cars. For example, many Alfa Romeo models had such a suspension. Recent cars with such a suspension can be called Smart.

10. Dependent suspension with drawbar.

This suspension can be considered as semi-independent. In its current form, it was developed in the seventies for compact cars. This type of axle was first serially installed on the Audi 50. Today, an example of such a car is the Lancia Y10. The suspension is assembled on a pipe curved in front, at both ends of which wheels with bearings are mounted. The bend protruding forward forms the drawbar itself, secured to the body with a rubber-metal bearing. Lateral forces are transmitted by two symmetrical oblique reaction rods.

11. Dependent suspension with linked arms.

The linked-arm suspension is an axle that is semi-independent. The suspension has rigid trailing arms connected to each other by a rigid elastic torsion bar. This design, in principle, causes the levers to oscillate synchronously with each other, but due to the twisting of the torsion bar, it gives them a certain degree of independence. This type can be conditionally considered semi-dependent. This type of suspension is used on the Volkswagen Golf model. In general, it has quite a lot of design variations and is very widely used for the rear axle of front-wheel drive cars.

12. Torsion bar suspension

Torsion bar suspension- these are metal torsion shafts that work in torsion, one end of which is attached to the chassis, and the other is attached to a special perpendicular lever connected to the axle. The torsion bar suspension is made of heat-treated steel, which allows it to withstand significant torsional loads. The basic principle of operation of a torsion bar suspension is bending.

The torsion beam can be positioned longitudinally and transversely. Longitudinal torsion bar suspension is mainly used on large and heavy trucks. Passenger cars typically use transverse torsion bar suspensions, usually on rear-wheel drive. In both cases, the torsion bar suspension ensures a smooth ride, regulates roll when turning, provides optimal damping of wheel and body vibrations, and reduces vibrations of the steered wheels.

Some vehicles use a torsion bar suspension to automatically level itself using a motor that tightens the beams to provide additional rigidity, depending on speed and road surface conditions. Height-adjustable suspension can be used when changing wheels, when the vehicle is raised using three wheels, and the fourth is lifted without the help of a jack.

The main advantage of torsion bar suspensions is durability, ease of height adjustment and compactness across the width of the vehicle. It takes up significantly less space than spring suspensions. The torsion bar suspension is very easy to operate and maintain. If the torsion bar suspension is loose, you can adjust the position using a regular wrench. All you have to do is crawl under the car and tighten the necessary bolts. However, the main thing is not to overdo it in order to avoid excessive harshness when moving. Adjusting torsion bar suspensions is much easier than adjusting spring suspensions. Car manufacturers vary the torsion beam to adjust the driving position depending on the weight of the engine.

The prototype of a modern torsion bar suspension can be called a device that was used in the Volkswagen “Beatle” in the 30s of the last century. This device was modernized by the Czechoslovakian professor Ledvinka to the design we know today, and installed on Tatra in the mid-30s. And in 1938, Ferdinand Porsche copied the Ledvinka torsion bar suspension design and introduced it into mass production of the KDF-Wagen.

Torsion bar suspension was widely used on military vehicles during World War II. After the war, torsion bar suspension was used mainly on European cars (including cars) such as Citroen, Renault and Volkswagen. Over time, passenger car manufacturers abandoned the use of torsion bar suspensions on passenger cars due to the difficulty of manufacturing torsion bars. These days, torsion bar suspensions are primarily used on trucks and SUVs by manufacturers such as Ford, Dodge, General Motors and Mitsubishi Pajero.

Now about the most common misconceptions.

“The spring sank and became softer”:

    No, the spring stiffness does not change. Only its height changes. The turns become closer to each other and the machine drops lower.

  1. “The springs have straightened, which means they have sagged”: No, if the springs are straight, this does not mean that they are sagging. For example, in the factory assembly drawing of the UAZ 3160 chassis, the springs are absolutely straight. In Hunter, they have an 8mm bend, barely noticeable to the naked eye, which is also, of course, perceived as “straight springs”. In order to determine whether the springs have sagged or not, you can measure some characteristic size. For example, between the bottom surface of the frame above the bridge and the surface of the bridge stock below the frame. Should be about 140mm. And further. These springs were not designed to be straight by accident. When the axle is located under the spring, this is the only way they can ensure favorable melting characteristics: when rolling, do not steer the axle in the direction of oversteer. You can read about steering in the “Car Handling” section. If you somehow (by adding sheets, forging the springs, adding springs, etc.) ensure that they become curved, then the car will be prone to yaw at high speed and other unpleasant properties.
  2. “I’ll cut a couple of turns off the spring, it will sag and become softer.”: Yes, the spring will indeed become shorter and perhaps when installed on a car, the car will sag lower than with a full spring. However, in this case the spring will not become softer, but rather harder in proportion to the length of the sawn rod.
  3. “I will install springs in addition to the springs (combined suspension), the springs will relax and the suspension will become softer. During normal driving, the springs will not work, only the springs will work, and the springs only with maximum breakdowns.” : No, the stiffness in this case will increase and will be equal to the sum of the spring and spring stiffness, which will negatively affect not only the level of comfort but also the cross-country ability (more on the effect of suspension stiffness on comfort later). In order to achieve variable suspension characteristics using this method, it is necessary to bend the spring with a spring until the spring is in a free state and bend it through this state (then the spring will change the direction of the force and the spring and spring will begin to work in opposition). And for example, for a UAZ low-leaf spring with a stiffness of 4 kg/mm ​​and a sprung mass of 400 kg per wheel, this means a suspension lift of more than 10 cm!!! Even if this terrible lift is carried out with a spring, then in addition to the loss of stability of the car, the kinematics of the curved spring will make the car completely uncontrollable (see point 2)
  4. “And I (for example, in addition to point 4) will reduce the number of sheets in the spring”: Reducing the number of leaves in a spring really clearly means reducing spring stiffness. However, firstly, this does not necessarily mean a change in its bending in a free state, secondly, it becomes more prone to S-shaped bending (winding water around the bridge due to the reaction moment on the bridge) and thirdly, the spring is designed as a “beam of equal resistance” bending" (those who have studied SoproMat know what it is). For example, 5-leaf springs from a Volga sedan and stiffer 6-leaf springs from a Volga station wagon only have the same main leaf. It would seem cheaper in production to unify all the parts and make only one additional sheet. But this is not possible because... If the condition of equal bending resistance is violated, the load on the spring sheets becomes uneven along the length and the sheet quickly fails in a more loaded area. (Service life is shortened). I really don’t recommend changing the number of sheets in the package, much less assembling springs from sheets from different brands of cars.
  5. “I need to increase the rigidity so that the suspension doesn’t penetrate to the bump stops” or “an SUV should have a stiff suspension.” Well, first of all, they are called “breakers” only by the common people. In fact, these are additional elastic elements, i.e. they are specially placed there so that it can be punched through to them and so that at the end of the compression stroke the stiffness of the suspension increases and the necessary energy capacity is provided with less rigidity of the main elastic element (spring/spring). As the rigidity of the main elastic elements increases, the permeability also deteriorates. What kind of connection would it seem? The limit of traction that can be developed on a wheel (in addition to the coefficient of friction) depends on the force with which the wheel is pressed against the surface on which it is traveling. If a car is driving on a flat surface, then this pressing force depends only on the mass of the car. However, if the surface is not level, this force begins to depend on the stiffness characteristics of the suspension. For example, imagine 2 cars of equal sprung mass of 400 kg per wheel, but with different suspension spring stiffnesses of 4 and 2 kg/mm, respectively, moving on the same uneven surface. Accordingly, when driving over a bump 20cm high, one wheel was compressed by 10cm, the other was released by the same 10cm. When a spring with a stiffness of 4 kg/mm ​​is expanded by 100 mm, the spring force decreased by 4 * 100 = 400 kg. And we only have 400kg. This means there is no longer any traction on this wheel, but if we have an open differential or limited slip differential (LSD) on the axle (for example, a screw “Quaife”). If the stiffness is 2 kg/mm, then the spring force has decreased by only 2 * 100 = 200 kg, which means 400-200-200 kg is still pressing and we can provide at least half the thrust on the axle. Moreover, if there is a bunker, and most of them have a blocking coefficient of 3, if there is some traction on one wheel with worse traction, 3 times more torque is transferred to the second wheel. And an example: The softest UAZ suspension on leaf springs (Hunter, Patriot) has a stiffness of 4 kg/mm ​​(both spring and spring), while the old Range Rover has approximately the same mass as the Patriot, on the front axle 2.3 kg/mm, and on the rear 2.7kg/mm.
  6. “Passenger cars with soft independent suspension should have softer springs” : Not at all necessary. For example, in a MacPherson type suspension, the springs actually work directly, but in double wishbone suspensions (front VAZ classic, Niva, Volga) through a gear ratio equal to the ratio of the distance from the lever axis to the spring and from the lever axis to the ball joint. With this scheme, the suspension stiffness is not equal to the spring stiffness. The spring stiffness is much greater.
  7. “It’s better to install stiffer springs so that the car is less rolly and therefore more stable” : Not certainly in that way. Yes, indeed, the greater the vertical stiffness, the greater the angular stiffness (responsible for body roll under the action of centrifugal forces in corners). But the transfer of masses due to body roll has a much smaller effect on the stability of the car than, say, the height of the center of gravity, which jeepers often very wastefully throw at lifting the body just to avoid sawing the arches. The car should roll, the roll does not count as bad. This is important for informative driving. When designing, most cars are designed with a standard roll value of 5 degrees at a circumferential acceleration of 0.4 g (depending on the ratio of the turning radius and the speed of movement). Some automakers set the roll angle to a smaller angle to create the illusion of stability for the driver.
And what are we all about suspension and suspension, let's remember, The original article is on the website InfoGlaz.rf Link to the article from which this copy was made -

The “chassis” consists of a set of components that are designed to move a vehicle along the road. Its mechanisms allow drivers to move with a certain comfort, since it is the main factor that directly affects safety. You can drive a car with a broken seat or a dented fender, but it is a malfunction of the chassis that can cause accidents on the road.

The chassis of a vehicle includes such elements as the frame or body, wheel suspensions, axle beams, tires and wheels. Each element performs its own functions, allowing drivers and passengers to move in comfortable conditions, without experiencing various mechanical vibrations, and ensuring safety in emergency situations. Chassis mechanisms connect the car body with the wheels, and also regulate the forces acting on the car, vibration and shaking. When a car travels on the chassis at high speed, the chassis protects it from slow vibrations.

Body

For many passenger cars, the chassis function is performed by the body rather than the frame, unlike trucks, buses or motorcycles. The body includes attachments and a frame. The chassis of the car is usually mounted on a frame.

Suspension

Suspensions are a number of devices whose main task is to connect the wheels of a vehicle and its body. It transforms, absorbs and softens impacts that can be transmitted from the road surface to the body. There are two types of pendants. They are divided into independent and dependent. Unlike dependent suspension, which is considered somewhat outdated, independent suspension allows wheels located on a common axis to move in a vertical plane, regardless of each other. This is the type of suspension that is most often used in modern vehicles.

The main requirements for suspensions are: smoothness; full compliance of the steering drive and wheels; strong connection between wheels and body; strength and long service life of parts.

The front suspension consists of: spring, brake disc, steering knuckle, compression buffer, stabilizer bar, wheel hub, shock absorber, upper and lower control arm, and upper and lower ball joint.

The chassis of a vehicle is connected to its body using elements such as shock absorbers and springs. The main function of springs is to soften the shock received from the road. However, at this moment the car may begin to sway, and then shock absorbers come to the rescue, dampening suspension vibrations.
An equally important part is the anti-roll bar. If the car rolls to the side when turning, it begins to twist and correct the position of the body.

The rear suspension is also divided into independent and dependent. It consists of a spring, shock absorbers, a compression stroke buffer, an additional compression buffer and a pressure regulator drive lever.

Tires and wheels

The next elements of the chassis are tires and wheels. Wheels consist of a disk and a tire. Tires are designed to soften impacts from bumps due to their elasticity and the compressed air they contain. They can be summer, winter or all-season. They are also divided into diagonal and radial. Diagonal tires have greater strength, while radial tires have more elasticity.

Causes of car chassis breakdowns

Regular loads on various elements of the chassis, which do not stop even after the movement has stopped, can lead to various breakdowns.

  • If your vehicle begins to have difficulty cornering at high speeds or requires a lot of effort to keep it on the roadway, there is a good chance that the vehicle's undercarriage needs to be repaired.
  • Another indicator is that the body can oscillate and sway when braking and when cornering. The reason may lie in failed shock absorbers, broken springs or suspension elements.
  • Vibration is felt when moving. Vibration may occur due to rear shock absorbers that are worn out; damaged springs; due to the fact that the tire pressure does not meet certain standards; or that the wheel hub bearings are in poor condition.
  • While the car is moving, the suspension begins to knock. The problem may arise due to loose mounting bolts or deformed wheel rims.
  • Knocking and creaking of shock absorbers occurs due to their breakdown; loosening of the reservoir or piston, as well as fluid leakage.
  • Creaking noise when braking on corners. As a rule, such a squeak occurs due to a malfunction of the shock absorbers or anti-roll bar.
  • Fluid begins to leak from the shock absorbers. This is possible due to the destruction of the rod seals or the ingress of foreign mechanical particles onto the sealing edges.

Diagnostics of the vehicle chassis and its repair

As soon as the slightest suspicion arises that the chassis is malfunctioning, it is necessary to deliver the vehicle to a service center, where specialists will diagnose it using equipment specially designed for this. The more often a vehicle is used, the more closely it is necessary to monitor its chassis, the diagnosis of which should preferably be done every 30 thousand kilometers.
It should be remembered that the repair of the chassis must be approached responsibly. Of course, you can simply replace all the parts, but in this case, the cost of repairs will be quite high. The best option would be to conduct diagnostics and identify a list of unsuitable elements.

Diagnostics of the vehicle chassis includes:

  • inspection of shock absorbers, levers, springs, support cups;
  • checking steering tips, ball joints;
  • state of nodes;
  • checking wheel bearings;
  • checking the tightness of the brake system and hydraulic systems of the machine;
  • determining the degree of wear of discs, hoses, brake pads and drums.

Regular diagnostics allows you to identify problems with the vehicle's chassis at an early stage, when there are no clearly defined signs of a malfunction of any elements. After checking all the faults, the technicians will help identify problems that the car may have in the future and prevent their occurrence. Based on the diagnostics, specialists draw up a list of necessary repairs and begin to carry them out.