The concept of a suspension has come into use since the dawn of the automotive industry. But own developments at that time it was not yet and the cars received this unit by inheritance from horse-drawn carts. Points like softness, comfort, handling were not even mentioned.
When maximum speed the first cars at 6 km / h, these questions were not at all relevant. But over time, the suspension on longitudinal elliptical springs became unusable.
On high speeds the requirements for the chassis changed, so in the pre-war years a double-wishbone design was invented, which is successfully used to this day.
Double wishbone suspension device
The double wishbone suspension can be called a prototype of other designs, since its modification has led to a number of new solutions. Dividing the upper arm into two separate ones brought out. And replacing the upper arm with a telescopic arm is at the heart of the idea.
The double wishbone suspension, as the name suggests, consists of two wishbones, an upper and a lower, which are mounted one below the other.
Lower arm is movably attached to the body. The fastening method should be described in detail. The fact is that the supporting part of such a suspension is a beam or subframe. This decision was provoked by huge loads on the body, which led to its destruction. The mobility of the lever is provided by silent blocks.
Upper arm can be attached to the body or to the beam. This is not so important, because all the load goes to the spring, and the upper arm acts as a support for the hub. On the opposite sides on the levers are designed ball joints for fastening steering knuckle and ensuring its rotation about the vertical axis.
The main elastic element that takes all the shocks when driving over irregularities is spring... It is performed with different coil pitch to avoid resonance.
Multi-link suspension has been installed on cars since the middle of the twentieth century. It is currently the most popular. The car suspension consists of assemblies and parts. It is designed to create an elastic connection between the car frame and its wheels. With its help, the load on the wheels and the body is reduced, it dampens vibrations, and also helps to control the position of the car body on the road when driving, especially when cornering. Thus, the suspension makes the car more stable on the road with a smoother ride.
The multi-link suspension is most often installed on the rear axle, but it is quite possible to install it on the front axle. In addition, it is installed on all types of drives: front-wheel drive cars, rear-wheel drive and with four-wheel drive... Multi-link suspension is a collective concept, as indicated by the name "multi-link". It does not have a clear design, but it combines the advantages of a double wishbone suspension with trailing arms and wishbones. Thus, it was possible to achieve optimal kinematics and control effect. The multi-link suspension makes the car's movements smoother, reduces noise levels, and makes it easy to drive on the road.
The design of the suspension consists in the fact that the wheel hubs are attached by means of four levers, which allows for adjustment both in the longitudinal and transverse planes. For the suspension to work correctly, it is necessary to correctly calculate the stiffness of the joints and the flexibility of the levers. For optimum dimensions, the suspension is mounted on a subframe. The design is complex and is done with a computer.
Into the design multi-link suspension includes the following units and parts:
- a stretcher that serves to secure the levers;
- hub bearing;
- longitudinal and transverse levers;
- springs;
- shock absorbers;
- stabilizer lateral stability.
The subframe is the basis of the structure. The wishbones are attached to it, which are connected to the hub support. They ensure the position of the hub in the transverse plane. Their number can be from three to five. In the simplest design, three are used: one upper and two lower - front and rear. 
The upper arm is designed to connect the wheel support to the subframe and transmits transverse forces. The rear is subject to the main load from the weight of the vehicle frame, which is transmitted through a spring. The front bottom is responsible for wheel toe-in. The trailing arm is attached to the body by a support, its function is to hold the wheel in the direction of the longitudinal axis. The other side connects to the hub support. Each wheel is equipped with its own trailing arm.
The hub contains bearings and wheel mounts. The bearings are attached to the support with bolts. A helical spring is designed for loads in the suspension. It is supported by the rear lower wishbones. One of the components of the multi-link suspension is the anti-roll bar, which serves to reduce the roll of the car body when it is cornering. In addition, the stabilizer provides good grip rear wheels with the road. The anti-roll bar is secured with rubber mounts. The rods are connected to the hub supports with special rods. Shock absorbers are connected to the hub support and are most often not connected to the spring.
Pros and cons
When evaluating the suspension, its consumer properties are taken into account: vehicle stability on the road, ease of control and comfort. Most often, motorists are not interested in the technical details of the car. These issues are dealt with by the engineers who create it. They choose the type of suspension, they select optimal dimensions and specifications individual nodes. During development, the machine undergoes many tests, therefore it meets all the requirements of the consumer.
It is known that comfort and handling are properties that are often opposite, as they depend on the stiffness of the suspension. They can be combined only in complex multi-link suspensions. The smooth running of the car is ensured by silent blocks and ball joints, as well as a well-defined kinematics. When hitting obstacles, shocks are well damped. All suspension elements are attached to the subframe thanks to powerful silent blocks, so the interior is isolated from wheel noise. The main advantage is controllability. 
This pendant is used on expensive cars, providing good grip of the wheels with the road surface and the ability to clearly control the car on the road.
The main advantages of the multi-link suspension:
- wheels are independent of each other;
- low weight of the suspension, thanks to aluminum parts;
- good adhesion to the road surface;
- good handling when cornering;
- the possibility of using in a 4 × 4 scheme.
A multi-link suspension requires high-quality roads, so it quickly wears out on domestic roads... The complexity of the design makes the suspension cost very expensive. Many manufacturers use non-separable levers on their models. Because of this, their cost is quite high.
Suspension diagnostics and repair
A multi-link suspension requires constant maintenance and, if necessary, timely repair. Despite the complexity of the design, you can check the condition of the multi-link suspension yourself.
For diagnostics, the car must be driven to inspection pit or jack it up. During the check, you should have on hand a car service manual, which describes its main parts and gives the necessary recommendations.
First of all, the shock absorbers are removed and checked for cracks. Then the integrity of the ball bearings, rods, levers, silent blocks is checked. All mounting bolts and rubber seals are checked. All parts must not be damaged in any way. If damaged parts are found, they must be replaced: either independently, using the diagrams in the manual, or at a service station.
On the rear suspension, in addition to shock absorbers, it is necessary to check the rods and seals. Next to the rear suspension is exhaust pipe, which may be the reason for the appearance extraneous sounds... The muffler should be carefully inspected, shaken in different directions, check the fasteners. These actions can remove the resulting extraneous sound.
If you regularly diagnose the car and carry out its repairs in a timely manner, this will extend its service life and increase driving safety.
Video "Repair of the front multi-link suspension"
The post shows how to replace the rear bushings of the front levers on a Ford Focus.
AT in general terms the device of the double wishbone suspension is quite simple. There are two levers, usually A-shaped, with the base of the triangle facing the wheel. The levers are fixed movably. Inner side the lower arm is attached to the subframe or, if the body is not load-bearing, to the frame, and the upper arm to the body. By the outside 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 a vibration-damping elastic element, 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 the mutual arrangement of the levers and the ratio of their lengths. Short levers of the same length are practically not found, since if they are present, when the car overcomes unevenness, 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 from the point of view of handling. As a result, the upper arm is usually 1.5 to 1.8 times shorter than the lower one. This makes it possible to achieve such a change in the camber of the wheels so that the wheel outer with respect to the center of rotation (as the more loaded one) always remains perpendicular to the road surface, which in turn means the maximum ability to transfer the side load.
By the way, the MacPherson strut, which we talked about last time, can be considered an inverted "two-lever". The lack of lateral displacement of the upper end of the strut characteristic of the MacPherson strut is in fact equivalent to the very long upper arm in a double wishbone suspension. Now the nature of the kinematic flaws of the suspension on the guide strut becomes clear.
Other advantages of a double wishbone suspension are better noise insulation and transfer of less loads to the body, 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 correct adjustment of the "two-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 when it comes to the rear suspension. As a result, a double wishbone suspension is now almost unrealistic to find on front-wheel drive compacts with a transverse motor. This type of suspension also complicates the design of body zones crumpled upon impact.
Additional complications arise with the use of double wishbones in the rear suspension. The fact is that the more and more powerful engine (that is, the higher the torque), the more the suspension arms flex during braking and acceleration. Most powerful cars are rear-wheel drive, and their natural instability is only aggravated by this effect. Even with a simple release of the gas in a corner without pressing the brake pedal, negative convergence wheels ("socks apart"). The wheel external in relation to the bend as more loaded determines the behavior of the car, and the car shows a pronounced oversteer until it loses control.
It is for this reason that for a long time I did not give up my positions. rear axle... But technological progress will sooner or later solve any problem. First, the Porsche engineers, faced with the difficulties described in the 928 with a front-mounted 8-cylinder engine, decided to turn the elasticity of the levers to the good of the case. They attached longitudinal "breaking" links to the lower arms of the rear suspension. When the wishbones are bent back during braking, the rods turn the wheels "toes in".
The Porsche 928 was truly renowned for its handling, and the solution was named the Weissach Bridge, after the town of Weissach in Baden-Württemberg, where the Porsche test site is located. It was a piecemeal solution that paved the way for a more replicable solution.
In 1982, the designers of Daimler-Benz on the 190 (W201) model 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 suppressed by additional levers. The upper and lower arms in the suspension are double (which already gives four in total), and in plan they form a trapezoid. When the ends of the levers are moved back during braking, the sides of the trapeziums work in much the same way as the rods of the Weissach bridge, giving the wheels a reverse motion, and so eliminating instability. The fifth lever is oriented obliquely forward and, when the machine rolls sideways, steers in favor of light understeer, regardless of the amount of braking.
Since the days of the distant 80s, most high-speed cars have a multi-link rear suspension, made according to a similar principle. Of course, the task of positioning the levers in this case is much more complicated and requires careful three-dimensional computer modeling, which greatly limits the use of "multi-link". For example, at the "golf class" level, this decision can serve as a criterion for the model to belong to premium segment this market sector. The presence of a multi-link suspension on the rear wheels 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 rear.
Double wishbone suspension - common type independent suspension... The design of the double wishbone suspension is based on the use of two levers, an upper and a 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, as the speed of cars increased, its imperfection made itself felt more and more, and as a result of the efforts of engineers and inventors, it was double-wishbone.
Cars of the early twentieth century, so unlike modern ones, were far from the concepts of "comfort" and "handling". And this is exactly what the buyers of not cheap cars lacked.
Achieve acceptable driving performance succeeded with the beginning of the use of independent suspensions. They are like most automotive development, migrated to civilian cars 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 car body was above the bridge girders, 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 even before World War II, it is still considered the most balanced and optimal for a passenger car. In addition, on the cars of the most famous Formula 1 racing series, a "two-lever" is used. Russian motorists are not by hearsay familiar with this design - on, from "Kopeyka" to "Seven", the front suspension was independent, double wishbone.
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 the silent blocks, rests on a beam or subframe, and the upper one - on the body. Other ends of levers,.
To save space and achieve optimal suspension kinematics, levers of different lengths are used. The upper, short, is made in the form of the letter "A", and the lower, in the form of the letter "L".
A spring, torsion bar, air spring or semi-elliptical spring can be used as an elastic element in a double wishbone suspension. True, the last one is on passenger cars practically not found and is used only on light trucks.
Together with the shock absorber, the elastic element is attached at one end 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 advantage. When driving through irregularities, shocks during operation of the suspension are damped more efficiently, which in better side affects the level of ride comfort. And most importantly, this type of independent suspension is by far the most reliable.
If it is so good, why isn't it installed on all cars? The problem is that the double wishbone suspension has a significant drawback. The fact is that the upper lever “eats up” the engine compartment quite noticeably. And if you consider that the overwhelming majority modern cars front-wheel drive, with a transverse engine, the "two-lever" simply does not have room in the body. Therefore, almost all cars of the A-, B- and C-class are content with a compact and cheaper to manufacture. For the same reason, the double wishbone 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 comes another minus of the "two-levers". The fact is that now the levers are made non-separable. That is, both the ball joint and the silent blocks are made in one piece. And the levers themselves, to reduce unsprung masses, are mainly made of aluminum. Therefore, when, say, "penny" silent blocks or a ball joint are worn out, you have to buy an expensive lever entirely.
The condition of the suspension elements can be diagnosed independently. To do this, it is enough to jack up the desired wheel, and then, using the assembly, check the condition of the ball bearings and silent blocks. The latter are most often calculated for the entire service life of the vehicle and do not require attention. But the most vulnerable spots in the double wishbone suspension are the ball joint and the shock absorber. Despite the simplicity of the design, it is better to entrust the repair to professional car mechanics, but, with the appropriate skills, devices and desire, you can do it yourself.
The article describes the principle of operation, the pros and cons of a multi-link suspension, as well as the device. The main faults are listed, differences from MacPherson and beams. At the end of the article, a video review of the multi-link suspension.
The content of the article:
The Multilink suspension, or in other words the multi-link suspension, is by far the most common among those used on the rear axle of the car. To the extent of progress, this view can be found on the front or rear axle of the car, respectively, both front-wheel drive and rear-wheel drive. Examples of use on the front axle are automobiles audi brands... To understand the principle of operation and the structure of the mechanism, we will consider everything in order.
The history of the emergence of multi-link suspension
For the first time, they started talking about the multi-link back in the middle of the last century, which is one of the subspecies of independent suspension. To be more precise, the first production car with this type of mechanism officially presented to the public was the 1960 Jaguar E-type. Then for the first time, engineers installed such a system on the rear axle of a car. Over time, the technology was introduced to the front axle of cars. audi... Subsequently Multilink appeared on the Porsche 928 in early 1979, the modernized version appeared on the Mercedes-Benz 190. In comparison with the original suspension, modified by Mercedes engineers, it learned to deflect the rear loaded wheel into the corner, steering the front wheels. The car went through turns perfectly, as if on the rails of a train.
The main trick of the system is amazing smoothness, almost no noise and excellent handling in any conditions road surface... Essentially it is upgraded suspension on double wishbones... The engineers simply took each lever and cut it into two separate pieces, so it turns out that the Multilink consists of at least 4 levers. Some manufacturers use 5 levers per wheel.
Progress did not stop there. As an example, BMW engineers went further with the first use of active multi-link rear suspension with steering. In addition to the levers, the set also includes steering rods associated with on-board computer... The driver was given the opportunity to choose a comfort mode (comfortable, sporty or intermediate options), due to which the wheel steering option changes (neutral, excessive, insufficient).
Principle of operation and device Multilink
As already mentioned, Multilink is most often used on the rear axle of the car, but options for using the system on the front axle of the car are not excluded. To understand how both options work and their structure, we will consider each axis separately.
Since the front wheels are always movable and serve to direct the movement of the car, respectively, the device of the suspension itself will be an order of magnitude more complicated than at the rear. The front multi-link includes the following main parts:
- shock absorbers;
- anti-roll bar;
- springs;
- jet thrust (to limit the movement of the hub in the longitudinal direction);
- transverse levers (to ensure the inclination of the wheel vertically and horizontally). In some models, they can provide longitudinal movement of the wheel;
- ball bearings;
- stretcher supports;
- stretcher.
When the wheel hits an obstacle, the main shock is taken by the spring and shock absorber. They dampen all vibration and forces that fall on the car wheel from the road surface, thereby minimizing their transfer to the body. Accordingly, the steering system of the front wheels is similar to the suspension on double wishbones.
Rear multi-link suspension
The design of the rear multi-link is, in fact, similar to the front, but with the exception of the possibility of turning the hub. The simplest options include one trailing arm and two wishbones. The main support is a shock absorber strut connected to the wheel hub. Depending on the manufacturer, the design may vary and includes up to 5 levers. The lower arm, in turn, is considered to be load-bearing, holds the weight of the body and the spring.
As for the spring and shock absorber, they can be installed separately or together, similarly. A characteristic plus in the rear multi-link suspension is the presence cross stabilizer stability, which also gives additional comfort and better handling. The most expensive part is considered to be the bearing lower arm, which receives the bulk of the load, the rest of the arms and rods act as guides.
One feature of the Multilink car on the rear axle is the wheel steering system. Rear wheel inertia, in particular on high speeds, affects vehicle handling during cornering. In other words, the wheel steering resists turning, thereby trying to stay on the same trajectory, avoiding the rear axle skidding. The technology is not new and it can be said that it has come from pre-war times. So, in particular, the military Mercedes G5 jeep was equipped with a steering system. The wheels change the steering angle minimally according to the front wheels, although in fact this is practically not noticeable.
In the photo, the front multi-link suspension
- Upper arm;
- Swivel stand;
- Stand support;
- Telescopic stand;
- Wheel bearing;
- Wheel hub;
- Guide lever;
- Stabilizer bar;
- Carrying lever;
- Subframe supports (4 pcs.);
- Transverse stabilizer;
- Stretcher.
The photo shows the rear multi-link suspension Audi
- Shock absorber;
- Spring;
- Stretcher;
- Anti-roll bar;
- Hub;
- Front wishbone;
- Trailing arm support;
- Upper wishbone;
- Lower wishbone;
- Trailing arm.
Cross arm is an equally important structural element. On the one hand, it is connected to the wheel bearing, on the other hand, to the vehicle body frame or supporting structures. As a rule, there are several levers (from three to five). There are three main levers (rear lower, front and upper) in the standard classic set. The rear carries the weight of the car body, distributed through a spring. The front lower arm is responsible for the convergence of the wheel of the machine, and the upper arm is responsible for the transfer of lateral force and connects the subframe with the support body.
In addition to the parts listed above, the list of main parts also includes a hub support, an anti-roll bar, a stabilizer bar, special rods, ball joints and various kinds of connections. As you can see, the independent multi-link suspension reminds many of its predecessor on. On the other hand, despite the similarities, the operation and maintenance of such a Multilink is much more difficult.
Each car mechanism has its pros and cons, ease of use, comfort and other little things. The independent multi-link was no exception, in accordance with the complex device, and accordingly the repair is serious.
Among the positive points, or as they say, the plus of the multi-link, one can note:
- Maintaining the toe-in angle at the time of work. In McPherson, the camber is disturbed relative to the body when the wheel is displaced. Multi-link suspension keeps the wheel in an upright position at any overload, regardless of the position of the body;
- Smooth running of the car, quiet operation of the entire mechanism. This effect is achieved due to a variety of rubber-metal elements for connection, as well as levers, which in turn dampen vibration;
- The main plus of the multi-link is, of course, the exclusion of the possibility of wheel displacement. In contrast to the double wishbone suspension, where when overloaded, the wheel deflected relative to the body, which could result in a skid. In a multi-link, this factor is completely excluded, which means that the car's skid on the rear axle is not possible.
Modern manufacturers have gone to the trick of making such elements modular, which implies the simultaneous replacement of one or more assemblies. Therefore, you will have to buy not only a rubber-metal insert, but also the part to which it is attached. Therefore for normal work suspension, change the levers assembly, which leads to a significant increase in the cost of maintenance of the mechanism. Although our specialists still find a way out, they repair only worn out parts.
The main differences between the multi-link suspension from McPherson and Beams
In accordance with the structure and method of operation, the multi-link suspension is significantly different from the Beam and MacPherson suspension.
| The main differences between the multi-link suspension from Beams and McPherson | ||
| Multi-link | McPherson | Beam |
| Fully independent suspension | Simple design and small dimensions | Reliable and simple design |
| Reduced sprung weight | Not expensive to manufacture and maintain | |
| Better comfort and handling | Average comfort level | Simple maintenance |
| Stable road grip | Versatility (front or rear vehicle axle) | Ease of installation |
| Independent lateral and longitudinal adjustment | Good suspension travel | Correct wheel kinematics |
| Expensive to maintain | Difficulty of maintenance (shock absorber strut) | Poor comfort (vibration and noise are transmitted to the body) |
| Complexity of repair and adjustment | Average level of controllability | |
| Complex construction | Variable camber and kinematics | Better to install on front-wheel drive only |
| Short service life | The suspension is heavy in weight | |
Possible malfunction of the multi-link suspension
Like any mechanism, the car's multi-link suspension fails sooner or later. Despite the complexity and reliability of the design of this type independent suspension, it quickly fails, especially during active driving, and requires increased maintenance of the mechanism as a whole. Many owners of cars with this type of mechanism insist that it is worthwhile to change worn-out parts in a timely manner, so that in the future they will get rid of the breakdown of whole composite (often levers) and all kinds of accidents.
You can carry out the diagnostics of the multi-link suspension yourself; for this, it is enough to drive the car into the inspection pit, raise the necessary wheel with a jack and use a pry bar or other tool to sway the wheel levers on the sides. For example, you can install a pry bar between two arms or another part of the car body. If backlashes of the silent blocks are found, then they must be eliminated immediately, this greatly affects the further angle of the wheel and leads to uneven wear of the tires.
Diagnostics of the multi-link also includes checking shock absorbers, ball, bushings and rubber seals, various levers and rods. Parts that have failed should be immediately replaced with serviceable parts. It is worth noting that when buying, carefully consider the quality of the products, and also do not save on such details. Subsequently, the savings can lead to accidents or worse situations. Before the beginning renovation works carefully study the literature on your car model, as there may be features and nuances of suspension repair.
Price of multi-link suspension parts
It is not worth talking about the specific cost of a multi-link part for all cars, since each manufacturer modernizes it to suit their needs and accordingly sets their price. To understand all the same how much it will cost an average repair, consider the price of parts using the example of Audi A5 2016
| Spare parts for multi-link suspension Audi A5 2016 | |
| Name | Price from, rub. |
| Shock absorber | 3292 |
| Shock absorber spring | 2950 |
| Shock absorber support | 902 |
| Spherical bearing | 1219 |
| Silentblock | 505 |
| Cross arm | 3068 |
| Lower suspension arm | 6585 |
At first glance, it would seem that prices are not as high as for spare parts, but if we consider that silent blocks fail quickly, and, as a rule, they need to be changed in sets (for the left and right side). In addition, it must be borne in mind that on audi models The A5 is multi-link on the front and rear axles, that is, on 4 wheels. Accordingly, the cost of repairs will be 4 times more.
Having considered the independent multi-link suspension of the car, we can say that it differs in comfort, excellent characteristics handling and keeps the vehicle on the road. But there are also disadvantages, not very cheap service, expensive spare parts and, of course, bulky dimensions that are not suitable for compact cars... To all, maintenance and repairs need to be done more frequently than other types of suspension.
Video review of a multi-link car suspension:
