How does a multi-link suspension work? Multi-link suspension (Multilink): device, diagram and photo Independent multi-link suspension.

14.07.2019

Body

Since for any vehicle one of critical systems that affect the comfort and safety when driving is the suspension. Designing a multi-link suspension, as the most the best option, is important point for the automaker. For the first time they started talking about it back in the middle of the last century, and today it has received well-deserved recognition and demand on most passenger cars, rear-wheel drive and all-wheel drive, where it is most often installed on the rear axle.

The device and principle of operation of the multi-link suspension

Almost any multi-link suspension includes a number of required elements:

levers - longitudinal and transverse;
hub support;
stretcher;
shock absorbers and springs.

Instead of the last two elements, a pneumatic rack can be used. The main role in the multi-link rear suspension is played by a subframe, to which transversely located levers are attached, connected, in turn, to the hub support. This suspension option can consist of three or five levers.

The process of designing a multi-link suspension is very complex, and is carried out only with the help of computer simulation. Each lever in this system is responsible for a certain moment in the behavior of the wheel - a change in lateral movement or camber. As a rule, designers provide for the independent operation of each link in such a mechanism, and often the levers are given a strictly defined shape, which is necessary for engineers to create a body of the intended shape. You can learn about the evolution of the suspension and its main features by watching the video:

Benefits of a multi-leverage system

In many cars, especially in non-premium segments, comfort and good handling are often mutually exclusive. The creation of a multi-link independent suspension allowed designers to make almost any car comfortable for passengers, and at the same time easy to drive. Among the main advantages of the course multi-link suspension are the following:

all wheels of one axle are completely independent of each other;
the possibility of using aluminum parts in the design allows to reduce the weight of the suspension itself;
excellent grip of each wheel with the road surface, which is especially important when driving on a wet track or in ice;
maintaining optimum vehicle control even on high speed, sharp maneuvering and high-speed passage sharp turns;
thanks to powerful silent blocks, with the help of which the elements of the multi-link suspension are attached to the subframe, it was possible to achieve good insulation of the cabin from noise;
the possibility of using in vehicles equipped with front, rear or all-wheel drive.

It has a multi-link suspension not only pluses, but also minuses. As the main one, it should be noted the complexity of the design. In addition, most automakers see the need to install non-separable levers, the cost of which is quite impressive. For a multi-link suspension, roads with high-quality pavement are highly desirable, which in our country is the exception rather than the rule. from here - frequent need repair, which is difficult to carry out on your own, and contacting specialists is expensive.

Is it possible to save a multi-link suspension on bad roads

Despite the rather expensive operation, car owners almost never doubt which is better - a beam or a multi-link suspension. In terms of comfort and safety, these systems are simply incomparable. To maintain this type of suspension in optimal condition, it is required constant control and service. Despite the complexity of the whole design, many care manipulations can be performed independently. Especially if there is a viewing hole or a lift.

When servicing a multi-link suspension, you must first of all be guided by the manufacturer's recommendations set out in the manual. First of all, shock absorbers are checked - the presence of cracks, dents or smudges indicates the need for replacement. After this, rods, ball, silent blocks are subject to inspection. Attention is paid to fasteners, which, if necessary, are tightened, as well as to all rubber seals. Multi-link suspension rear axle at inexperienced drivers may arouse suspicion if there are extraneous noises when driving from behind.

The most common reason for this is the exhaust pipe. When self-checking, you should pay attention to it first of all - its fastening must be reliable, and if it is weakened, it must be tightened enough to extraneous sound disappeared. Riding a car with damaged elements found in the multi-link suspension is quite dangerous. So, a slightly bent lever causes an angle of the wheel, which leads not only to rapid wear rubber, but also noticeably changes the behavior of the car on the road for the worse.

Greetings, car enthusiasts! How to make the wheels of the car move independently of each other and do not have a rigid connection between them? Answer: apply independent suspension. There are several options to implement this scenario, but one of the most popular today is the multi-link rear suspension (Multilink). Surely you have heard about it, and, by the way, it is also successfully used on the front axle.

Hit among independent pendants

Manufacturers and owners of cars fell in love with the “multi-link” for a reason. This miracle of engineering has really unique characteristics - it has a high smoothness, makes the car perfectly manageable and even makes less noise than its counterparts.

The only serious drawback is the price, due to the complexity of manufacturing and customization. Despite this, you can see it on cars and trucks.

Compared to other species, the "multi-link" is quite young. It is believed that it first appeared on the Porsche 928 sports car in the late 70s of the last century. Other German companies quickly picked up the idea and began to improve the independent multi-link system.

So, for example, in 1982 Mercedes released a model whose rear suspension could steer in the direction of the turn. And Audi began to install it on the front axle of cars.

The more leverage the better...

What is so magical in the "multi-link"? In fact, it is an evolution of the classic double wishbone suspension.

If in the latter each of the transverse levers is cut into two, then we get the most primitive multi-link, and in this case we already get an advantage - you can adjust the longitudinal and transverse position of the wheel independently of each other.

And if you add trailing arms to them, as they do now, then you get a fairy tale in general.

Let's take a closer look at the multi-link system. The main elements of the suspension are:

stretcher;
hub support;
shock absorber;
spring;
transverse levers;
trailing arm;
stabilizer roll stability.

The work of the suspension consists of the coordinated interaction of all these pieces of iron, and each plays a very important role.

The support of the entire structure is a subframe. Almost all levers are attached to it through silent blocks (rubber-metal bearings) at one of the ends. By the second end they are fixed on the hub support through similar silent blocks.

Wishbones, which can be up to five pieces, provide reliable fixation of the wheel in the transverse plane.

The name of the trailing arm (it, by the way, is only one per wheel) also speaks for itself, but unlike the transverse ones, it is attached to the car body with the end opposite to the hub support.

In the "multi-link" elastic elements (shock absorber struts and springs) are not combined into one design and are located separately. Their task is to give an adequate response to various loads.

As for the anti-roll bar, then, as in other types of suspensions, it is engaged in preventing body roll when cornering and improving wheel adhesion to the roadway.

If we compare the multi-link suspension with others, then at first glance it seems to be a heap of various levers and pieces of iron. So it is, the bulkiness of this system is obvious, which, of course, is reflected in its cost. However, due to its exceptional properties (smooth suspension, handling), it is in great demand.

By the way, another important point, which is the “skeleton in the closet” of a multi-link design, is the poor tolerance of low-quality roads. Agree, in our realities this is quite relevant. Although, on the other hand, regular preventive maintenance and diagnostics of elements will give many years of driving pleasure under any operating conditions.

Thank you for your attention, friends. I hope it was interesting. Subscribe, share on networks, and follow the latest publications.

IN in general terms the double wishbone suspension device is quite simple. There are two arms, usually A-shaped, with the base of the triangle facing the wheel. The levers are fixed movably. Inner side lower arm is attached to the subframe or, if the body is not load-bearing, to the frame, the upper arm to the body. Outside party the levers are movably connected to the rack carrying the wheel. In the case of the front suspension, the strut is swivel. Between the levers is an elastic element that dampens vibrations, which today usually consists of a spring and a telescopic shock absorber.

The greatest influence on the handling of a car equipped with such a suspension is exerted by the relative position of the levers and the ratio of their lengths. Short levers of the same length are practically never found, since if they are present, when the car overcomes bumps, the wheel will move not only in the vertical, but also in the horizontal direction. In other words, the track will change, which is an extremely undesirable effect in terms of handling. As a result, the upper arm is usually 1.5 to 1.8 times shorter than the lower arm. This makes it possible to achieve such a change in the camber of the wheels that the outer wheel in relation to the center of rotation (as more loaded) always remains perpendicular to the road surface, which in turn means the maximum ability to transfer lateral load.

By the way, the MacPherson suspension, which we talked about last time, can be considered an inverted “double-lever”. The lack of lateral displacement of the upper end of the strut, characteristic of the MacPherson layout, is in fact equivalent to a very long upper arm in a double wishbone suspension. Now it becomes clear the nature of the kinematic flaws of the suspension on the guide rack.

Other advantages of a double wishbone suspension are better sound insulation and the transfer of a smaller part of the loads to the body, the relative ease of repair.

There are also disadvantages. The cost of designing and maintaining such a suspension is higher than that of MacPherson, because the competent setting of the “double-lever” is a rather complex geometric task. In addition, the horizontal orientation of the suspension “eats up” space under the hood, as well as in the luggage compartment, if we are talking about the rear suspension. As a result, double-wishbone suspension is now almost unrealistic to find on front-wheel drive compacts with a transverse engine. This type of suspension also makes it difficult to design areas of the body that are crushed upon impact.

Additional difficulties arise with the use of double wishbones in the rear suspension. The fact is that the larger and more powerful the engine (that is, the higher the torque), the more the suspension arms bend during braking and acceleration. The majority powerful machines just rear-wheel drive, and their natural instability is only aggravated by such an effect. Even with a simple release of gas in a turn without pressing the brake pedal, negative toe-in occurs (“toes apart”). The outer wheel in relation to the turn as more loaded determines the behavior of the car, and the car demonstrates a pronounced oversteer before losing control.

Exactly because of this reason for a long time the continuous rear axle did not give up its positions. But technical progress sooner or later solves any problem. At first, Porsche engineers, having encountered the described difficulties on the 928 with a front-mounted 8-cylinder engine, decided to turn the elasticity of the levers to the good of the case. To the lower arms rear suspension they attached longitudinal "breaking" rods. When the transverse levers are bent back during braking, the rods turn the wheels “toes inward”.

The Porsche 928 was really famous for its handling, and the solution was called the Weissach Bridge, in honor of the city of Weissach in Baden-Württemberg, where test site Porsche. It was a piece of cake that paved the way for a more replicable solution.

In 1982, the Daimler-Benz designers on the 190 (W201) used the world's first multi-link rear suspension. Despite the fact that there were five levers on each side, it was still the same “two-lever”, only all its “twists” were now stopped by additional levers. The upper and lower arms in the suspension are doubled (which already gives a total of four), and in terms of they form a trapezoid. When the ends of the levers move back under braking, the sides of the trapezoids work in much the same way as the rods of the Weissach bridge, giving the wheels a reverse movement, and thus eliminating instability. The fifth lever is oriented obliquely forward and, when the car is leaning sideways, it steers in favor of slight understeer, regardless of the intensity of braking.

Since the distant 80s, most high-speed passenger cars have a multi-link rear suspension, made according to a similar principle. Of course, the task of locating the levers in this case is much more complex and requires careful three-dimensional computer modeling, which greatly limits the use of “multi-links”. For example, at the golf class level, this decision can serve as a criterion for a model to belong to the premium segment of this market sector. The presence of a multi-link suspension on the rear wheels ah reduces the requirements for the front suspension, so it is not uncommon to combine an inexpensive MacPherson strut on the front wheels with an advanced “multi-link” at the rear.

The shock absorber is a hydraulic unit consisting of a body in the form of a cylindrical tube with smooth inner walls, filled with a working fluid (in automotive industry- oil). Inside the housing is a piston connected to a rod. When the rod is compressed, the piston, as if in a syringe, presses working fluid. Which is forced to flow from one cavity (under the piston) to another (above the piston in a single-tube shock absorber or into the cavity between the housings - in a two-tube one). For this, special calibrated valves are provided. Depending on the design, the upper end of the rod and / or the lower eye of the shock absorber have holes with a pressed rubber bushing - for attaching the unit to the body and suspension arms.

By selecting the valve capacity, you can adjust the desired damping characteristic of the shock absorber for compression and rebound. The difference between these values determines the ability of the shock absorbers to effectively dampen vibrations in the suspension (quickly, progressively compress, "taking a blow", and slowly decompress - so as not to provoke repeated vibrations of the body).

Other names

“Single-tube” (slang name for a single-tube shock absorber), “two-tube” (respectively, the name of a two-tube shock absorber). For McPherson type suspensions, the shock absorber is sometimes referred to as the "strut", although this term is more correctly applied to the entire assembly, and not just to the shock absorber.

Purpose

A shock absorber is a mandatory attribute of the suspension of any car, designed to dampen / prevent repetitive vibrations and / or buildup of the body when the car is moving on bumps.

Without shock absorbers, the suspension springs will compress and decompress - under the influence of external forces when driving through road bumps - in the mode of self-oscillations (possibly with increasing amplitude). Shock absorbers are just designed to dampen these vibrations. In general, ride comfort, as well as handling characteristics, are very dependent on the type of shock absorbers, their serviceability and even the operating temperature (it is not uncommon for shock absorbers to “boil” during intensive work - for example, on a bumpy road or heavy off-road).

Symptoms

Shock absorber failure can be identified by a characteristic knock from under the bottom of the car - the cause, as a rule, is a worn mount. When visually inspected, black oil streaks on the shock absorber body eloquently indicate its failure.

In motion, faulty shock absorbers lead to a lack of effective vibration damping - the car body sways, "dances" on bumps.

The most reliable data on the state of shock absorbers (their serviceability and residual life) can be obtained by testing a car on a vibration stand. A modern computerized stand takes into account the design of the suspension (before testing, the brand of the car is stored in memory) and checks the shock absorbers and other suspension parts, simulating real road loads. So the test data shows working condition or the need to replace shock absorbers. At the same time, the price of the service will be determined both by the cost of new shock absorbers and the amount of work to dismantle / install racks (which does not differ much for cars of different brands).

Replacing shock absorbers

The cost of replacing shock absorbers is largely determined by the type of suspension. In principle, it is necessary to distinguish between a two-lever suspension and a McPherson strut type design. In the second case, the repair of shock absorbers will be estimated based on the total cost of removing the front struts, disassembling them, replacing the front shock absorber, reassembly stands and their installations.

The rear multi-link suspension may also require replacement of the rear suspension struts. For a dependent suspension scheme, replacing rear shock absorbers is usually easier. Below are typical cases of suspension repair by replacing shock absorbers.

Replacing the front shock absorbers (with a two-lever scheme):

the operation is performed on a "pit" or a lift (there is no need to raise the car high - for the convenience of replacement, the suspension must be slightly compressed!);
open the hood, through the hole in engine compartment unscrew the upper fastener of the rod (to fix it from rotation, it is necessary to hold the rod special key or thin pliers)
completely remove the stem fasteners, the engraving and support washer of the pillow - then you can remove the upper shock absorber support pillow itself;
under the lower suspension arm, unscrew the two nuts securing the shock absorber support (carefully so as not to lose the self-locking washers!);
the old shock absorber is removed down - through the window of the lower suspension arm;
on the removed shock absorber, the rubber support pad is removed from the rod;
using two keys, the bracket fastening nut is unscrewed (the bolt head is held by the second key) - and the entire bracket is removed;
the removed bracket can be rearranged to another shock absorber - if new node comes without it!
a new shock absorber is installed in the reverse order (before installation, it is recommended to extend its stem as much as possible! And put a washer, pillow on the upper end in advance, and also screw on the nut);
the second shock absorber of the front suspension is changed similarly.

Replacing McPherson type front struts:
Since the McPherson strut includes both the shock absorber and the front suspension spring (with two support cups), and the telescopic rod, as well as a number of other parts, replacing the shock absorber will involve complete withdrawal racks and disassembly. Very often, this operation is called just that: “shock absorber strut replacement”, or simply “strut replacement” - although they still mean replacing the shock absorber. The algorithm of work is as follows:

the car is installed on a flat area or hung out on a lift;
the hood opens, the nut securing the support to the rack is slightly loosened (in this case, the shock absorber rod should be held with a second key);
the hand brake is tightened, the wheel bolts are loosened;
the desired side of the car is lifted with a jack (if the operation is not carried out on a lift);
wheel removed, front brake hose carefully laid aside (first remove it from the holder on the rack);
to facilitate the replacement of the shock absorber strut, it is recommended that all bolts and nuts be thoroughly cleaned of dirt (especially the strut-to-knuckle fastener assembly) and treated with WD-40 grease;
the fastener of the steering tip to the rack lever is unscrewed, with the help of a hammer (or better, a special puller!) The tip is knocked out of the rack;
from below, the nuts connecting the rack and the steering knuckle are unscrewed (it is better to use union heads with a crank);
certain difficulties may arise with removing the bolts from the mounting sockets - they should be carefully knocked out with a thin metal rod, periodically unscrewing the bolt from the back;
finally, under the hood, three nuts securing the strut to the support cup of the body are unscrewed (do not completely unscrew the last nut so that the strut does not fall down!)
When fasteners the struts to the knuckle are taken out, you can finally unscrew the upper nut of the attachment to the body cup and remove the strut.

To replace the shock absorber, the rack must be disassembled:

using a screed, you need to compress the spring of the rack (at the same time, place the paws of the screeds evenly so that the spring does not warp);
as soon as the spring moves away from the support plate, you can unscrew the top nut;
the strut support is removed (together with the bearing and rubber pads - so as not to assemble this assembly in detail when installing a new shock absorber);
the compressed spring is removed (if necessary, it can be replaced with a new one - simultaneously with the replacement of the strut shock absorbers);
the boot and bump stop are removed from the stem of the rack (they are planted with an interference fit - you need to make a little effort!);
a chipper and anther (removed earlier or also new) are put on new racks;
a new spring is installed (before installation, it is also pulled together to fit under the support cups of the rack);
the spring is put on the rack - you need to make sure that the lower coil exactly sits on the support belt!
the upper support cup is turned over - a bearing is placed on it (there is always a “top” mark on the outer ring of the bearing);
the bearing is covered with a cup, an elastic band is installed on top - the resulting “pact” is put on the rack rod with a new spring and tightened with a nut (at the same time, the rack rod must be kept from turning);
when tightening the nut, make sure that the upper coil of the spring lies exactly along the perimeter of the support cup!
the assembled module of the new rack is installed on the car in the reverse order of rack removal (see above).

As you can see, the price of replacing struts (as well as the list of necessary work) can be higher than the cost of replacing shock absorbers on a double wishbone suspension.

It should be noted that the rear multi-link suspension also contains struts. Accordingly, work on their replacement will be somewhat more complicated (compared to replacing rear shock absorbers dependent suspension - this, as a rule, is much simpler).

What needs to be done on the car:

For a double wishbone suspension, replacing the shock absorbers does not affect the wheel alignment. But the replacement of the front shock absorbers and / or McPherson strut assembly should always be accompanied by a subsequent adjustment of the wheel alignment!

Such additional work such as replacement of the support bearing, replacement of the strut support, etc. require disassembly of the entire assembly. So, it is logical to carry them out simultaneously with the replacement of the front pillars.

When carrying out work, it is recommended to check the remaining suspension units (in particular, the condition of silent blocks, tie rod ends, ball bearings, stabilizers and suspension arms, as well as the integrity of brake hoses, wheel bearing seals, etc.).

By the way, in order to prevent damage / contamination of the CV joint anther, when carrying out work on replacing shock absorbers or replacing shock absorber struts, it is recommended to close the "grenade" of the CV joint with polyethylene.

Shock absorber life

The resource of suspension elements largely depends on the condition of the roads, driving style, and typical vehicle loading. And also from the climate, the brand of the car and a number of other important factors. Therefore, the service life of individual elements can vary significantly and any figures should be taken as indicative only. For shock absorbers, the resource is about 30 thousand kilometers, but in fact it can be either less or much more than this value.

What threatens untimely replacement

The operation of a car with faulty shock absorbers leads to a sharp deterioration in driving comfort (increased buildup, “rolling”, the car responds poorly to the steering wheel). In addition, like any suspension element, the shock absorber affects the stability and handling of the car, that is, its active safety.
And since we are talking about safety, the cost of replacing the shock absorber struts is disproportionately less than possible consequences from ignoring the fault!

The characteristics of the suspension elements have a decisive influence on the handling and driving characteristics of the car. And if it is almost impossible to change levers, springs, ball bearings and silent blocks in search of the best “habits” of a car on the road, then it is quite possible to “play” with the characteristics of shock absorbers (even by selecting and replacing them multiple times)!
In addition to special struts that the manufacturer positions as sports shock absorbers (and which really improve responsiveness and make the car “sharper”), there are adjustable shock absorbers. When they are installed, it becomes possible to easily change the response to compression and rebound (separately), adapting the car to certain track conditions. At the same time, the installation and replacement of shock absorber struts is no different from that for primary equipment units!

Do not confuse "gas" shock absorbers and gas stops. The latter are used, for example, to hold the hood or trunk lid. These stops consist of a cylindrical tubular body and a movable stem - in this they really look like shock absorbers. But inside the body, the stops contain gas under pressure, which prevents the rod from sharply compressing - this ensures the holding property of the stop. Although with a little more effort it can be easily “defeated” and squeezed, folded until the stem completely goes inside the body.

In a "gas" shock absorber, the working fluid is oil - in its normal state it is not under pressure. But if external forces (tensile or compressive) are applied to the stem, the shock absorber "rests" because the viscous oil dissipates the energy of the external influence when it is throttled through the working valves. To improve the characteristics of the shock absorber inside its body, closer to the lower end, there is a small volume filled with gas (most often nitrogen) and covered with a solid piston. Kinematically, this piston is not connected to the rod piston. But with an increase in oil pressure, this additional piston compresses the gas volume. At the same time, the gas "does not go anywhere" and does not mix with the main working oil. But the presence of such a sealed "spring cavity" inside the body favorably affects the operation of the shock absorber - due to the difference in viscosity of the compressible oil and gas.

Thus, the "gas" shock absorber still remains liquid. But with improved damping performance.

Double wishbone suspension is a common type of independent suspension. The design of a double-lever suspension is based on the use of two levers, upper and lower, attached at one end to the body and the other to the wheel hub. At the dawn of the automotive era, cars differed from horse-drawn carriages only in the presence of an engine. Accordingly, the suspension in the form of a beam on elliptical springs migrated to them practically unchanged. However, its imperfection, as the speed of cars increased, more and more made itself felt, and as a result of the efforts of engineers and inventors, it was double-lever. Cars of the early twentieth century, so unlike modern ones, were far from the concepts of "comfort" and "handling". Namely, this was not enough for buyers of by no means cheap cars. To achieve acceptable driving performance succeeded with the beginning of the use of independent suspensions. They are like most automotive development, migrated to civil vehicles from motorsport. High speeds and dependent suspensions turned out to be incompatible things. Handling on bends remained at the level of the same horse-drawn carriages. In addition, the body of the car was above the beams of the bridges, so the center of gravity was high. And if there were no problems when driving in a straight line, then fast turns had to be overcome almost at the speed of pedestrians. Despite the fact that the double wishbone suspension appeared on cars before the Second World War, it is still considered the most balanced and optimal for a passenger car. car. In addition, on the cars of the most famous Formula 1 racing series, a “two-lever” is used. Russian motorists are familiar with this design firsthand - on, from the Kopeyka to the Seven, the front suspension was independent, double-lever.

Double wishbone design

Also, like almost a hundred years ago, it consists of two levers located transversely, one above the other. The lower one, through silent blocks, rests on a beam or subframe, and the upper one rests on the body. Other ends of the levers. To save space and achieve optimal kinematics of the suspension, levers of different lengths are used. The upper, short, is made in the form of the letter "A", and the lower one, in the form of the letter "L". As an elastic element in a double-lever suspension, a spring, a torsion bar, an air spring or a semi-elliptical spring can be used. True, the latter is practically never found on passenger cars and is used only on light trucks. Together with a shock absorber elastic element one end is attached to the lower arm, and the other to the car body.

Pros and cons of double wishbone suspension

As mentioned above, the independent double wishbone suspension gives the car good handling. But this is not its only merit. When driving over bumps, shocks during suspension operation are damped more efficiently, which in better side impact on ride comfort. And most importantly, this type of independent suspension is by far the most reliable. If it is so good, then why is it not put on all cars? The problem is that the double wishbone suspension has significant disadvantage. The fact is that the upper arm quite noticeably "eats" the engine compartment. And if you consider that the vast majority of modern cars are front-wheel drive, with a transverse engine, then the “two-lever” simply does not have a place in the back. Therefore, almost all A-, B- and C-class cars are content with compact and cheaper to manufacture. For the same reason, double-lever suspension is practically not used on the rear axle of cars, because it reduces the useful volume of the trunk. Sooner or later, any, even the most reliable suspension, wears out. Here another minus of the “two-lever” pops up. The fact is that now the levers are made non-separable. That is, both the ball joint and silent blocks are made in one piece. And the levers themselves, to reduce unsprung masses mainly made of aluminium. Therefore, when, say, “penny” silent blocks or a ball joint are worn out, you have to buy an expensive lever as a whole. The condition of the suspension elements can be diagnosed independently. To do this, it is enough to jack up right wheel, and then, using the assembly tool, check the condition of the ball bearings and silent blocks. The latter are most often calculated for the entire life of the car and do not require attention. But the most vulnerabilities in a double wishbone suspension are spherical bearing and shock absorber. Despite the simplicity of the design, it is better to entrust the repair professional car mechanics, but, with the appropriate skills, devices and desire, you can do it yourself.

Since for any vehicle one of the most important systems that affect the comfort and safety while driving is the suspension. Designing a multi-link suspension as the best option is an important consideration for a car manufacturer. For the first time they started talking about it back in the middle of the last century, and today it has received well-deserved recognition and demand for most passenger cars, rear- and all-wheel drive, where it is most often installed on the rear axle.

The device and principle of operation of the multi-link suspension

Almost any multi-link suspension includes a number of mandatory elements:

levers - longitudinal and transverse;
hub support;
stretcher;
shock absorbers and springs.

Benefits of a multi-leverage system

all wheels of one axle are completely independent of each other;
the possibility of using aluminum parts in the design allows to reduce the weight of the suspension itself;
excellent grip of each wheel with the road surface, which is especially important when driving on a wet track or in ice;
maintaining optimal controllability of the car even at high speed, sharp maneuvering and high-speed passage of sharp turns;
thanks to powerful silent blocks, with the help of which the elements of the multi-link suspension are attached to the subframe, it was possible to achieve good insulation of the cabin from noise;
the possibility of using in vehicles equipped with front, rear or all-wheel drive.

It has a multi-link suspension not only pluses, but also minuses. As the main one, it should be noted the complexity of the design. In addition, most automakers see the need to install non-separable levers, the cost of which is quite impressive. For a multi-link suspension, roads with high-quality pavement are highly desirable, which in our country is the exception rather than the rule. hence the frequent need for repairs, which are difficult to carry out on their own, and contacting specialists is expensive.

Is it possible to save a multi-link suspension on bad roads

Despite the rather expensive operation, car owners almost never doubt which is better - a beam or a multi-link suspension. In terms of comfort and safety, these systems are simply incomparable. To maintain this type of suspension in optimal condition, constant monitoring and maintenance is required. Despite the complexity of the whole design, many care manipulations can be performed independently. Especially if there is a viewing hole or a lift.

When servicing a multi-link suspension, you must first of all be guided by the manufacturer's recommendations set out in the manual. First of all, shock absorbers are checked - the presence of cracks, dents or smudges indicates the need for replacement. After this, rods, ball, silent blocks are subject to inspection. Attention is paid to fasteners, which, if necessary, are tightened, as well as to all rubber seals. The multi-link rear axle suspension can be suspicious for inexperienced drivers if there are extraneous noises when driving behind.

Named after an American engineer Ford Earl Steele MacPherson (Earle Steele MacPherson), who first applied it on stock car Ford models Vedette 1948. It was later used on the Ford Zephyr (1950) and Ford Consul (1951). It is the most common type of independent suspension, which is used on the front axle of the car.

The design of the MacPherson strut suspension is an evolution of the double wishbone x suspension, in which the upper wishbone is replaced by a shock absorber strut. Due to its compact design, McPherson suspension is widely used on front-wheel drive cars, as it allows you to transversely place the engine, gearbox and other attachments in engine compartment. Main advantage of this type suspension - simplicity of design, as well as a large suspension travel that prevents breakdowns. At the same time, the design features of the suspension (swivel mounting of the shock absorber strut, big move) lead to a significant change in the camber (the angle of the wheel to the vertical plane). In a turn, the camber goes into the plus, the wheel seems to be tucked under the car, and in connection with this, the ability of the car to turn at high speed deteriorates sharply. This is the main disadvantage of MacPherson suspension, which is why this type of suspension is not used on sports cars and premium cars.

MacPherson suspension has the following device:

1. spring

2. shock absorber strut

3. roll bar

4. wishbone with ball joint

5. subframe

6. knuckle

The suspension is attached to the body through a subframe, which is the supporting structure. It is rigidly attached to the body or through silent blocks to reduce vibrations transmitted to the body. Two triangular transverse levers are attached to the side of the subframe, which are connected to the steering knuckle through a ball joint. The steering knuckle rotates the wheel due to the steering rod, which is attached to it from the side. Shock absorbers with springs mounted on them are attached directly to the steering knuckle. Two rods from the lateral stability shock absorber, which are responsible for lateral stability, are connected to the shock absorbers through ball joints. As you can see, the suspension device is simple enough to describe it in 3 lines.

Advantages and disadvantages

pros

+ low cost

+ easy to maintain

+ compactness

- Poor cornering handling

- Transmission of road noise to the body

MacPherson strut video:

2. Double wishbone suspension( Double wishbone suspension)

Unfortunately, it is still not known for certain who was the first to invent the double wishbone suspension; it first appeared in the early 30s on Packard cars. This company was based in the heart of the American automotive industry - Detroit. The first Packard car rolled off the production line in 1899, the last one was built in 1958. After the 1930s, many american cars began to be equipped with a double-lever suspension, which cannot be said about Europe, because. due to the size of the car, there was not enough space to accommodate such a suspension. A lot of time has passed since then and now double wishbone suspension is considered perfect view independent suspension. Due to its design features, it provides better control over the position of the wheel relative to the road, because the double levers always keep the wheel perpendicular to the road, for this reason the handling of such cars is much better.

Double wishbone suspension can be used on the front and rear axles of the car. Suspension is used as front suspension on many sports cars, executive and business class sedans, as well as Formula One cars.

Double wishbone suspension device:

1. upper wishbone
2. shock absorber
3. spring
4. drive shaft
5. tie rod
6. lower wishbone

The double wishbone suspension design includes two wishbones, a spring and a shock absorber.

Lever arm may be Y-shaped or U-shaped. Unlike MacPherson, there are two levers, each of the levers is attached to the body through silent blocks and to knuckle through a ball joint. The upper arm, as a rule, has a shorter length, which gives a negative camber angle of the wheel in compression and a positive one in tension (rebound). This property gives additional stability the car when cornering, leaving the wheel perpendicular to the road, regardless of the position of the body.

Advantages and disadvantages

pros

+ perpendicular position of the wheel relative to the road in turns

+ peck resistance

+ improved handling

Minuses

- big size

- price

- laborious maintenance

Video of the double wishbone suspension

3. Multi-link suspension (Multilink).

Further development of the double wishbone suspension. This is the most common suspension on the rear axle at the moment. This is due to the fact that when using a double wishbone suspension when braking or releasing gas (on rear wheel drive vehicles) there is a change in the angle of convergence of the rear wheels. Because the suspension is attached to the subframe through silent blocks, which are deformed during braking and the rear wheels begin to look outward. It would seem that there is nothing terrible in this phenomenon, but imagine that you went over the speed in a turn and decided to resort to braking, braking in a turn by itself is no longer very good idea. And then the external loaded wheel begins to look out of the turn, the car very quickly acquires oversteer and the consequences can be the saddest. You can prevent this phenomenon by replacing silent blocks with swivel joints, but then comfort will suffer greatly, because no one wants to knock their teeth on bumps. So the engineers went the other way.

Multi-link suspension is installed on both front-wheel drive and rear-wheel drive vehicles. Its purpose is to create a sufficiently elastic connection between the body and the wheels of the car. This type of suspension is different increased resistance cornering and smooth running, as it tends to dampen the largest part of the vibrations created during movement on uneven road surfaces.

Such a suspension was originally installed on the rear axle of the car. Currently, there are many options for installing it on the front axle, regardless of the drive of the car, whether it is full, front or rear. It does not have a specific design and is a combination of a double wishbone suspension with longitudinal-transverse levers. Thus, low noise is achieved at large road bumps, smooth running, improved handling and a large range of adjustments.

Independent suspension device

The design features begin with the fact that wheel hubs are mounted on four levers, and therefore, there are additional adjustments to the position of the hub. The levers, in turn, are mounted on a stretcher.

The number of levers can vary from 3 to 5. In the most elementary layout, two lower ones are used: front and rear, and one upper. The front, as a rule, is responsible for the wheel toe, the rear takes on most of the mass of the car, transmitted through the spring, and the top transmits lateral forces and connects the wheel support and the subframe.

Also, in the multi-link suspension, anti-roll bars are actively used, which are used to reduce the roll of the car when cornering. Stabilizers are mounted on the hub supports with additional levers, and in the upper part with rubber supports. Most often, such a stabilizer is closely connected with the spring.

Video - Independent suspension on a VAZ in operation

Advantages of the multi-link system

1. Complete independence of the wheels from each other.

2. Compared to any other type of suspension, the mass of an independent suspension is much less. This is due to the use of aluminum in the manufacturing process.

3. Possibility of application in 4x4 layouts.

4. Independent multi-link suspension ensures increased grip with pavement.

5. High cornering stability and smooth running.

Flaws

1. Subtle sensitivity to the quality of the road surface. The use of such a suspension on low-quality pavement leads to wear of the components very quickly.

2. The levers of this suspension are a non-separable element, therefore, in the process of repair, it is often necessary to change the entire assembly, which costs a lot of money.

Like any other type of suspension, a multi-link system requires increased maintenance. Timely replacement of worn parts will save you from the subsequent breakdown of still normal parts and accidents associated with a faulty suspension condition.

Diagnosis of malfunctions of an independent suspension can be carried out independently. To do this, you need to put the car on viewing hole, jack up the desired wheel and, using any mounting tool, shake the levers by inserting it into the gap between the two levers or any other parts (for example, between the lever and the subframe). The backlashes of the silent blocks found at the same time should be eliminated as soon as possible, since this greatly affects the angle of the wheels and contributes to uneven wear of the rubber.

Troubleshooting also includes checking the condition of shock absorbers, ball bearings, rubber seals and bushings, levers and rods. Faulty parts found must be replaced immediately. At the same time, when buying new parts, pay attention to their quality. Saving on the quality of suspension parts can, in consequence, play a trick on you on the road. Be very careful about this matter.

When troubleshooting, use the technical literature for the repair of your particular car model, since the layout and methods of mounting the suspension on other car models vary greatly.

It is worth paying attention that if knocks are heard in the rear of the car, then the source of noise can be not only the suspension system, but also a poor mounting of the muffler, which can touch the levers or rods.

Do not forget that the good condition of the independent suspension will keep good handling car, will relieve premature tire wear and is an excellent prevention of traffic accidents.

Multilink or multi-link suspension is the most common way to equip a car's wheel mount without a rigid connection between them. This type suspension is installed on almost all cars and surpasses the usual method of mounting the rear axle in its characteristics.

Multi-link suspension - what is it?

Modern cars differ from domestic and from their predecessors by a higher level of safety, stability and reliability. These criteria have been achieved through research and improvement of various parts, assemblies and mechanisms installed on modern cars. This also affected the multi-link suspension. Its changes and transformations made it possible to make the car more stable and obedient on the road.

- This is a complex of parts and assemblies that connect the body of the car with the wheels. It is designed to minimize dynamic loads, and also contributes to the uniform distribution of such loads on all supporting elements while the vehicle is moving. The multi-link suspension gives the desired smoothness while driving, gives excellent handling, and also helps to reduce noise in the cabin.

This node is a set of parts that make it possible to carry out adjustment in different planes. High level handling and smoothness is achieved using the following set of parts:

- longitudinal and transverse levers;

Stretcher;

hub support;

shock absorbers

And springs.

The subframe is the base, the supporting structure, the transverse levers are attached to it, which in turn are connected to the wheel hub support. This design provides a transverse position of the hub. On the other hand, all levers are securely attached to the spar or subframe. Today, cars are equipped with three or five-link suspension. The multi-link suspension can be installed both on the front axle and on the rear. If this is a front suspension, then the levers can be replaced with jet thrust. They are able to simultaneously perform the function of a stability stabilizer and a lever.

How does a multi-link rear suspension work?

At first glance, it may seem that the mechanism is quite complicated, but upon closer examination, everything turns out to be quite the opposite. Next, we will cover how the multi-link rear suspension works and much more.

As you know, the design of this mechanism includes levers, a shock absorber, springs, hub bearings, a stabilizer bar and a subframe. The levers are attached to the subframe and the vehicle frame. The transverse levers are fixed with the wheel hub, in the transverse plane ensure its stable position. task upper arm is the transmission of transverse loads and secure fastening subframe to the wheel. The front lower control arm is responsible for the wheel alignment of the vehicle. The rear lower arm takes the weight of the car body. The longitudinal arm fixes the wheels in the direction of the longitudinal axis. Fastening to the body in this case is carried out using a support. The other end of the lever is attached to the hub. This assembly contains bearings, wheel mounts and other necessary parts. As a rule, shock absorbers and springs are installed separately from each other. In order to reduce the angle of inclination of the car during cornering and bending, an anti-roll bar is used. The stabilizer is fastened with the help of rubber supports, the rods connect the rods and the hub supports.

This suspension design is the result of many years of improvement and research. She avoided emergencies, breakdowns, keep the car upright when cornering. It is more bulky than previous modifications, and also more expensive. However, this does not lose its popularity, partly due to the opportunities that the car owner gets.

Independent suspension - we put it in order with our own hands

Despite the seeming reliability and power independent suspension or its improved version of the multi-link design, is a mechanism that is prone to damage. This leads to the need for regular inspections and repairs.

Most malfunctions of an independent multi-link suspension can be fixed by hand. The main principle of successful repair is the timely noticed malfunction. The first signs of wear of the assembly can be seen after the car passes 40-80 thousand km. There may be a knock, a creak. Sounds intensify when crossing obstacles, potholes or speed bumps. The reasons may vary from the need to replace a small part that protects a particular joint with the subsequent cleaning of this assembly before carrying out complex repair. In this case, you may need qualified help and specialized equipment. At the service station, specialists will carry out all the necessary procedures, including diagnostics and repair of the rear suspension.

Fault diagnosis can be carried out in a garage. First of all, it is necessary to visual inspection all parts. Front Suspension:

- you need to remove the shock absorbers and inspect them for cracks, chips and other damage;

Then it is necessary to carefully inspect the ball bearings, silent blocks, lever and rod.

Particular attention in this area must be paid to rubber joints, seals and fasteners. If you notice damage, cracks, then you need to replace this part with a new one. There is a rubber gasket on the bottom of the car, it must also be intact.

Did you find a problem during diagnostics? Before you liquidate it, evaluate technical capabilities. If you are not sure, it is best to contact a specialist in a car service. After that, you can proceed to the diagnosis of the rear suspension. Here, too, the inspection begins with shock absorbers. Next, you need to devote time to rods and seals. In the process of inspecting the rear suspension Special attention take a look at the exhaust pipe. Sounds and squeaks can come from damage in it.

During inspection, it is necessary to tighten all threaded elements and lubricate all joints where necessary. If no damage is found, and the sounds continue to increase during movement, you should contact a specialist. The thing is that inept or incorrect actions can lead to damage or destruction. important element transmission of the car, and this can already result in expensive repairs.

Diagnostics and repair of the rear suspension

In order for each trip on an iron horse to give comfort and pleasure, it is necessary to regularly inspect and diagnose the chassis of the car. If you yourself could not detect and eliminate the characteristic sounds, you need to contact a car service. Specialists will carry out all the necessary procedures, including this will be:

- complex diagnostics and repair of the rear suspension, comprehensive diagnostics of all components of the suspension;

Restoration and repair work;

Repair or complete replacement individual parts or suspension assemblies;

Camber adjustment and front and rear suspension adjustment.

During all stages of work, car mechanics use special equipment, which cannot be installed in the garage or replaced with anything. professional diagnostics and repair of the rear suspension can be compared with treatment in an expensive clinic or surgery. pendant and chassis vehicles are not just a mechanism that provides movement and control of the movement process, but also ensures safety on the road. Therefore, neglect of squeaks, knocks or unusual rolls of the car on the road can lead to disastrous consequences.