Semi-independent torsion. The principle of operation of the torsion bar suspension, its device, the pros and cons

The main element of the torsion bar suspension is the torsion bar, which is a cylindrical metal rod,. In order for the torsion bar to spring well when twisting, it is made of durable steel that has undergone special heat treatment. At the same time, it withstands high mechanical torsional stresses and allows large twisting angles without permanent deformation. Torsion rods can have a round or square section, and also consist of metal plates.

Torsion suspension device

At one end, the torsion beam is rigidly fixed to the vehicle frame, and its other end is connected to the wheel hub through a lever. Vertical movements of the wheel lead to twisting of the torsion bar and the appearance of a springy reaction. Thus, a strong and elastic connection of the car body with it is ensured. To increase the reliability of the connecting nodes and protect against shock overloads, additional spiral springs and are used. Such a suspension system was widely used until recently in many types of vehicles.

How torsion bar suspension developed

The modern torsion bar suspension system found on today's vehicles is the result of a large number improvements to the part that was used for the first time on a car Volkswagen Beetle, which appeared in the 30s of the 20th century. The Czech scientist Ledvinka was the first to modernize the torsion bar and apply it on cars brands Tatra in the same 30s. Already in 1938, the similarity of the Ledwink torsion bar began to be massively used in the KdF-Wagen car company Ferdinand Porsche.

The famous Austrian engineer quickly appreciated the main thing - its low weight, which is so necessary and in demand in the army and sports cars as well as SUVs. Where there are strict requirements for the weight and dimensions of the car. And at present, this advantage of the torsion bar suspension is relevant and effective, as evidenced by their use on such heavyweights as the Ferrari F2001, Toyota Landcruiser, MAZ-547, etc. Ferdinand Porsche also developed torsion bars with double levers, the transverse rods of which were placed in steel pipes, located one above the other and played the role of a torsion beam.

French engineer André Lefebvre, constructor Citroen car TA, used such a virtue of the torsion bar as the dependence of the stiffness of the suspension on the length of the torsion beam. The longer the torsion bar, the softer the suspension. In addition, a long shaft, located along the longitudinal axis of the car, allows you to distribute the dynamic load received from the roadway over its entire frame. This improves the stability and controllability of the machine.

During the Second World War, torsion bars were actively used in armored and automobile military equipment. The torsion bar suspension was installed on the German "Panthers" and the Soviet "KV". Having successfully passed tests in combat conditions, these pendants became widespread in the post-war period. They were used by almost all car manufacturers in Europe and America. And 1961 is significant in that the torsion bar was first used on the front suspension. This car has become Jaguar E-Type. In America, such a suspension was used on Chrysler and Packard cars, and in the Soviet Union they were installed on ZILs, LUAZs and Zaporozhets.

Advantages and disadvantages

The location of the torsion beam under the body can be either longitudinal or transverse. For the most part, the longitudinal arrangement is used on large and heavy vehicles. On passenger vehicles more commonly used compact transverse torsion bars rear suspension. In both cases, the suspension is designed to solve the following tasks:

• maximum absorption of mechanical vibrations of the wheels and frame;
• stabilization of the position of the steered wheels;
• cornering angle adjustment.

The transverse suspension is limited in length by the machine's track width. On the sides of the body, the working ends of the transverse torsion bars are connected to suspension arms. Therefore, the softness of such pendants is also limited. Unlike transverse longitudinal beams, they do not have strict length restrictions, therefore, in terms of softness, such suspensions are not inferior to springs and springs. In addition, the longitudinal design of the suspensions creates additional technological conveniences when assembling the body of large cars.

The main advantages of torsion bar suspension include the following:

• it is more compact compared to the spring system and takes up much less space;
• ease of installation and maintenance;
• light weight;
• it allows you to easily and quickly install the necessary ground clearance without changing the details of the suspension design;
• high reliability and maintainability;
• long service intervals and ease of adjustment;
• it provides better handling vehicle in the event of a roll.

All maintenance of the torsion bar suspension basically comes down to tightening mounting bolts, which can be done with only . However, you should not use the principle “the stronger, the more reliable” in this case, since excessive tightening of the bolts can cause increased suspension stiffness.

torsion bar suspension, except heavy vehicles, used in production passenger cars. Example: Toyota Corolla Fielder where the rear torsion bar is used.

The main disadvantages of suspensions on torsion beams are:

• The tendency of a car with such a suspension to oversteer. When cornering, such cars begin to turn around, which requires increased attention from the driver. Such a tendency is most characteristic and noticeable on ZAZ cars, which are small in size.
• Sophisticated technology for the production and processing of torsion bars, providing the necessary high strength and elasticity of the material. To ensure the resistance of the metal to the occurrence of surface cracks, torsion bars undergo special surface hardening procedures using plastic deposits and other technologies. All these technological operations increase the cost of the suspension. Despite this, they find application in modern automotive technology to provide them high level comfort when driving different types road surfaces.
• The presence of needle bearings in the attachment points of the levers to the ends of the torsion beam with a limited mileage resource. Bearings tend to fail due to dust, water and dirt entering through cracks in seals and gaskets. Moreover, this happens more often due to the aging of the rubber material and exposure to aggressive environments than from driving style and its intensity. The main panacea for this trouble is to often look under the bottom of the car. Timely Service will allow you to replace the seals or bearings. In the worst case, the beam will have to be repaired or replaced, as the failed bearings flare the seats, which leads to a change in the camber. The resource of bearings is from 60 to 70 thousand km.

One of the reasons that limit the use of torsion bars is the difficulty of obtaining fully independent wheel suspensions that provide a high level of comfort. However, the presence of a torsion beam makes it possible to obtain sufficiently free suspensions if rotating beams are used at the ends. This achieves greater independence of the wheels and greater smoothness when driving. This suspension is especially effective on heavy vehicles such as the Peugeot 405 and Renault Laguna in which she experiences heavy load which improves ride comfort. On lighter Peugeot cars 106, 206, 306 such suspension will be less efficient and comfortable.

With the development of production technologies over time, torsion systems ceased to be used in passenger transport due to the high cost of manufacturing torsion beams and the specifics of operation passenger cars. Now they are used in most cases on trucks and SUVs from companies such as Dodge, General Motors, Mitsubishi Pajero, Ford.

Torsion bar suspension has been used in the automotive industry for about eighty years, it was first used on Citroen cars in the mid-thirties of the last century. A little later, the Germans became interested in this design and implemented it in the Volkswagen Beetle. IN domestic automotive industry torsion bar suspension was first used on the Zaporozhets car, the front suspension of which was made on the basis of two square-section torsion bars.

Currently this species suspension has become widespread among most automakers, due to its simplicity of design, compactness and low cost.

What is torsion bar suspension

In this type of suspension, the torsion bar plays the role of an elastic element. This is a kind of metal rod of a round or square section that performs twisting work. It can be either solid or assembled from several metal plates; there are slots at its ends for connection with other elements.

IN in general terms torsion bar suspension diagram is as follows. One end of the rod is fixedly connected to the body, the other - to the lever. The principle of operation is based on the elasticity of the torsion bar. The wheel of the car, moving in a vertical plane, spins it, due to which an elastic connection arises between the wheel and the car body. Unwinding to a normal state, the torsion bar returns the wheel to its original position. On the video you can see how this design works.

Data elastic elements have two features:

• their rotation is possible only in the direction of twisting;
• with their help, you can adjust the clearance of the car.

The use of torsion bars

This type of elastic elements is used in the most different types suspensions: on longitudinal or double transverse levers, as well as in semi-independent.

Trailing arm suspension

Its device is as follows: one or two elastic elements are located across the body, and trailing arms are attached to them. This design was used, as a rule, for the rear suspension of small cars, but is not currently used.

For the first time it was used on the Volkswagen Beetle, its front part had such a device. One of the cars with trailing arm rear suspension was Renault 16. This car is interesting in that it had different wheelbase left and right. The reason is that in its design rear axle two torsion bars were used, located one behind the other.

Independent double wishbone suspension

torsion bars in this case are located along the body, one on each side, with one end they are attached to the frame, and the other - to the transverse lever (usually to the lower, although in some cars they can be attached to the upper). The peculiarity of such a suspension is that the length of the torsion bars, and hence their elastic properties, can be adjusted in a very wide range (the longer the length, the easier the elastic element twists, therefore, softer suspension). Such a device has a front suspension of some off-road vehicles.

Semi-independent suspension

This variety occupies a special place among suspensions in which the torsion bar is an elastic element. It is an intermediate link between independent and dependent suspensions, which is why it was called semi-independent. Wide application she found among many cars from "A" to "C" class. Her device looks like this. Trailing arms, located one on each side, are interconnected by a torsion beam. At one end, each of them is attached to the car body, and at the other to the wheel hub.

The principle of its operation is based on the shape of the elastic element. The beam has a U-shaped cross-section, thanks to which it resists bending well, but twists easily. Therefore, the wheels are able to move in a vertical plane without depending on each other. The scheme of the torsion beam is shown in the photo.

Pros and cons of torsion bar suspension

Like any other design, torsion bar suspension has its pros and cons.

Its main advantages are as follows:

• compactness in comparison with a spring suspension;
• simple device and high reliability;
• light weight;
• the ability to quickly change the clearance of the car without making changes to the design;
• good maintainability;
• long service intervals.

Cons of torsion bar suspension:

1. worse handling than multi-link suspension(cars tend to oversteer);
2. complex technology for the production and processing of elastic elements;
3. limited service life of needle bearings in mounts trailing arms to the torsion beam (about 60-70 thousand km);
   if failed bearings are not replaced in a timely manner, the torsion beam will have to be repaired or replaced.

The history of the appearance of the torsion bar suspension dates back to the 30s of the last century, thanks to multiple improvements, it remains relevant to this day and is successfully used not only in civil, but also in military equipment. Moreover, the technology is not in demand by some modest firms, but is in service with companies recognized as industry leaders, such as Volkswagen, Ferrari, Citroen, Toyota, Jaguar, etc. At one time domestic producers also appreciated the torsion bar suspension and tested it for the first time on the legendary Zaporozhets, in which the front suspension includes a pair of square-shaped torsion bars. In view of this state of affairs, it would be useful to consider in more detail what a torsion bar suspension is and why interest in it has turned out to be so stable.

The basic element of a torsion bar suspension is a torsion bar (translated from French torsion - twisting), - an element made in the form of a cylindrical rod of increased elasticity, working on twisting in one direction. The shape of the torsion bar is not subject to a single standard, so in cross section it is mostly square or round. Another less common option is a lamellar torsion bar, which has a multilayer structure, also designed for torsion provided by joint work several plates.

In order to increase the torsional springiness, the steel used in the production of torsion bars undergoes a complex multi-stage heat treatment. Thanks to this, intense torsional stresses and large twist angles do not create problems for the suspension. Both ends of the torsion bar are movable, which is achieved through the use of bearings and splines that compensate for changes caused by work loads.

The torsion beam located under the body can occupy both longitudinal and transverse positions. The longitudinal version is found mainly in trucks, where chassis under constant stress. The transverse torsion bar suspension is installed on cars, especially rear-wheel drive ones.

Torsion shafts have different thicknesses, which affects performance indicators and suspension softness. To avoid rusting, the torsion bar is protected with a stable anti-corrosion paint or rubberized.

The principle of operation of the torsion bar suspension

Hummer H2 torsion bar suspension scheme: 1. Wheel hub; 2. Drive shaft; 3. Lower wishbone; 4. Upper wishbone; 5. Shock absorber; 6. Stabilizer roll stability; 7 Front differential; 8. Longitudinal torsion bar; 9. Subframe

The principle of operation of the torsion bar suspension is quite simple. Through spline connection one of the ends of the torsion bar is connected to the wheel hub by means of a suspension arm, and the other is fixed to the car frame. The axis of the lever and the axis of twisting of the torsion bar are located in the same plane. When vertical movement the wheel torsion bar is twisted, which causes a springy effect.

The tension during the period of action of the forces of raising-lowering is maintained. In this case, the load is softened and redistributed, which is directed to the body, which makes it possible to protect the car from the effects of high rigidity, including shock.

The cessation of external influence is accompanied by the return of the wheel to normal position. This occurs as a result of the untwisting of the torsion bar. The mechanism resembles the work of a spring, but the efficiency of the torsion bar is much higher.

Where is torsion bar suspension used?

The use of such a suspension was widely practiced during the Second World War. This applied to tanks and other armored vehicles. After such approbation, the technology was adopted by all leading European automakers and US companies. On the front suspension, torsion bars first appear in 1961 in Jaguar models E type. In the USSR, in addition to the Zaporozhians, they were integrated into ZILs and LUAZs. Later, due to their specificity, torsion bars were no longer used in passenger transport. Although some SUVs and trucks from manufacturers such as GM, Ford, Dodge Mitsubishi are still produced with a suspension based on torsion bars.

Despite their more than 80-year history, torsion bars have been and are used in the production of several types of suspensions:

• • on trailing arms - it was used in the rear suspension of small cars, but today it is no longer relevant;
  • independent system on double wishbones - currently successfully supports the performance of some SUV models;
  • semi-dependent (semi-independent) - widely used in passenger transport classes "A", "B" and "C".

Advantages and disadvantages

Regardless of the type of torsion bar suspension used, its presence helps the car to effectively cope with many tasks:

• smooth running;
• good absorption of frame and wheel vibrations;
• stabilization of the leading wheelset;
• the ability to adjust the degree of stiffness of the suspension;
• normal roll control.

If we take into account the ease of operation and maintenance, it can be separately highlighted that in many cases only a wrench is enough to bring the suspension back to normal, which is necessary to moderately tighten the mounting bolts. In addition, other positive aspects of torsion bar suspensions should be taken into account:

• compact size and light weight;
• no difficulties in installation;
• trouble-free clearance adjustment that does not require changes to the suspension;
• great working life and maintainability.

As for the disadvantages of the torsion bar suspension, here you need to focus on this:

• optional, but shaking may occur, especially on back seat, which is associated with rigid fastening, resulting in the transmission of strong vibrations;
• the appearance of noise, which is explained by the problematic protection of the body from vibrations and this is also due to a rigid mount;
• there is a possibility of oversteer, especially with small car sizes;
• the service life of needle bearings located at the junction of the torsion beam and levers is limited to 70 thousand kilometers.

Compared to products from the automotive industry with other types of suspension, buying a car with torsion bars is usually not so expensive, and the cost of maintaining it in order cannot be called excessive.

Related video

The torsion bar is a metal elastic element that works on twisting. As a rule, this is a metal rod of round section with a slotted connection at the ends. The torsion can consist of a set of plates, rods, beams of a certain section. Structurally, the torsion bar is attached at one end to the body or frame of the car, and at the other - to the guide element - the lever. When the wheels are moved, the torsion bar is twisted, which achieves an elastic connection between the wheel and the body. A feature of torsion bars is rotation in only one direction - in the direction of twisting. Another feature is that the torsion bar can be used to adjust the body height. Torsion bars are used in various types independent suspensions: on double transverse levers, on longitudinal levers, with connected longitudinal levers (torsion beam).

In a torsion bar suspension on double wishbones, the torsion bars are parallel to the body, so that their length and, accordingly, the elastic properties can be adjusted over a wide range. One end of the torsion bar is attached to the lower transverse arm (rarely to the upper arm), the other end to the vehicle frame. This torsion bar suspension design is used as a front suspension for off-road passenger cars - some models of American and Japanese SUVs. In a trailing arm torsion bar suspension, the torsion bars are connected to the trailing arms and, accordingly, are located across the body. This torsion bar suspension design is used as a rear suspension for some models of small cars. A special place in the designs of torsion bar suspensions is occupied by the so-called. torsion beam or trailing arm suspension. The guiding device of this suspension are two trailing arms rigidly interconnected by a beam. The trailing arms are attached to the body on one side, and to the wheel hubs on the other. The beam has a U-shaped section, so it has high bending rigidity and low torsional rigidity. This property allows the wheels to move up and down independently of each other. The torsion beam is now widely used as a rear suspension front wheel drive vehicles small and middle class. Due to its design, the torsion beam suspension occupies an intermediate position between the dependent and independent type of suspension, so its other name is semi independent suspension.

History of appearance

Torsion bar suspension has been used since the mid-1930s on French cars. brands Citroen. In the 1940s, torsion bars were used on racing cars Porsche. Subsequently, they were used by many other automakers. For example, Renault, ZIL and Chrysler. The use of torsion bar suspension was primarily due to good performance smooth running and simple design.

Types of torsion suspensions

Front independent torsion bar suspension on wishbones The front torsion bar suspension on wishbones (one or two depending on the design) consists of the following elements: Longitudinally located torsion bar, working on twisting and replacing the spring. The lower or upper arm that takes the main load, through which the force is transferred to the torsion bar. The damping element is a shock absorber that performs the function of damping vibrations. Anti-roll bar that compensates for body roll when driving. The compactness of the front torsion bar suspension on the wishbones allows efficient use of free space. For example, to install massive wheel drives. In this regard, torsion bars have become widespread in the production frame SUVs combining cross-country ability with the softness of the suspension. For example, Toyota Land cruiser 100 (mounting the torsion bar to lower arm) And Toyota Hilux Surf (torsion bar on upper arm). Torsion bars are also used on the front axle of commercial vehicles.

Rear independent suspension with transverse torsion bars

In the designs of rear suspensions with a longitudinal arrangement of levers, torsion bars are installed transversely. Legendary French Renault car 16, which was produced until the 1990s, was equipped with a front suspension with longitudinally located torsion bars, and a rear suspension with a transverse one. A feature of the elastic elements of the rear suspension was their location - one was behind the other, which structurally entailed a difference in the wheelbase on the sides of the car (one of the wheels was several centimeters closer to the front). The handling and stability of the car left much to be desired, however, it was the compactness of the torsion bar suspension that made it possible to significantly increase the volume luggage compartment, which largely determined the popularity of the model. Currently, such a suspension scheme is not used by automakers.

Semi-independent rear torsion beam

Semi-dependent U-shaped torsion beam, which has an integrated elastic rod, becomes more bending strength. At the same time, it allows the wheels of one axle to move slightly relative to each other when driving through bumps. This improves the handling and stability of the car. This suspension is used on the rear axle of most budget front-wheel drive cars.

Benefits of torsion bar suspension

✔ High running smoothness. ✔ Compact and light weight. ✔ High maintainability. ✔ Simple and reliable design.

Disadvantages of torsion bar suspension

✔ The complexity of the production of torsion bars. ✔ Mediocre car handling. Currently, the front independent suspension, where torsion bars are installed as elastic elements, is used in the production of trucks and SUVs that are not designed for dynamic driving. In addition, the torsion bar suspension is successfully used in tank chassis designs and other special tracked vehicles.

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A torsion beam refers to a type of suspension that uses a torsion bar as an elastic element. This metal rod is characterized by a round section, at the ends of which there is a slotted connection. The torsion itself includes:

• a set of plates;
• rods;
• beams of the established section.

The design of the torsion bar is attached at one end to the frame or body of the car, and at the other - to the lever. The rotation of the wheels contributes to the twisting of the torsion bar, due to this, an elastic fastening between the body and the wheel is achieved. Feature of the mechanism: it rotates only in one direction - towards twisting. Its other feature is that the torsion bar is used to adjust the height of the body. This type of suspension is used among independent suspensions:

• double wishbone;
• trailing arm;
• connected trailing arm.

Schematic device of a torsion bar suspension

Torsion bar suspension with double wishbone torsion bars are located along the body. This factor provides that their length, respectively, and elastic properties are adjusted in a wide range. As mentioned earlier, the torsion bar design is attached at one end to the body or frame of the car, and at the other to the lever. Some models of Japanese and American SUVs uses this mechanism as the front suspension of off-road cars.

In a torsion-type suspension, the trailing arms of the torsion bars are connected longitudinally, respectively, located across the body. This design looks like a rear suspension on some models passenger vehicles small class.

Schematic arrangement of a torsion beam

A special place in the designs of this type of suspension is given to the torsion beam. As a guiding device, two trailing arms are used here, which are attached to each other by a beam. The trailing arms are fastened on one side to the body, and on the other - to the wheel hubs. The beam is characterized by a U-shaped section. This factor gives the unit a greater degree of bending rigidity and less torsional rigidity. And thanks to this property, the wheels have the ability to move up and down from each other autonomously.

An exemplary schematic composition includes:

1. rubber-metal hinge;
2. shock absorber;
3. transverse beam (torsion bar);
4. twisted spring;
5. wheel hub;
6. trailing arm

Longitudinal or transverse placement

The placement of the torsion bar parallel to the longitudinal axis of the vehicle is characteristic of the front wheels certain types SUVs and commercial models. Torsion suspensions rear type characteristic exclusively cars designed for the small or lower segment of the middle class. In this case, they are characterized by a transverse arrangement relative to the body.

The features of each type of torsion bar suspension are reflected when it is necessary to resolve issues related to their support in a technically sound condition. Let's take rear-type torsion beams as an example. And let's look for an answer to the question regarding the restoration of car beams with our own hands.

Causes of malfunctions

• by the most weak point beams are bearings. The service life of bearings of any type is regulated by its wear. Needle type bearings are no exception, because no one has canceled the factors that accelerate depreciation. This part of the beam system is not subject to impact loads. Therefore, the impact of shocks from high-speed driving, unlike wheel bearings, they are unusual. In most cases, they suffer from carried dirt. Any sealant cannot be avoided from aging, and water will immediately flow through the smallest hole. As soon as moisture gets inside, you can say goodbye to the bearing. extraneous sounds, emanating from the beam on an uneven surface - signs of failure of the bearings. If you do repairs immediately, the owner of the car will get off with a simple replacement of worn parts. Neglect of this factor leads to a complete replacement of the shafts. After all, it was not in vain that standard terms for replacing bearings every 60 thousand km were developed, even though no signs were observed. When the wheels of the vehicle become in the shape of a house, it is unlikely that it will be possible to get out of the situation solely by replacing the bearings.
• Shock absorbers and springs. These problems are not very common in practice.
• Torsion as a source of malfunctions. Depending on the model, there may be two, three or four. The reason for the wear of each option is damage to the splines, with the help of which the torsion bars are connected to the pipe and levers, or the breakage of the rod. The fatigue strength of torsion bars is high, but not unlimited. Torsion bars settle in the same way as springs sag, while the clearance of the rear of the car decreases. Features of the torsion bar suspension allow, by reinstalling the torsion bars, not only to return the original position of the body, but also to increase the ground clearance, if necessary. However, fatigue stress gradually accumulates in the rod, and corrosion reduces the cross section of the torsion bar, which ultimately leads to breakage. There is nothing more to break in torsion beams.

Self-replacement problems

If it is necessary to dismantle the beam, it is unrealistic to cope with this work on your own. The part is characterized by significant weight and dimensions. Pressing out old shafts and further installation in their original place requires heating and related hot work. Without the help of a special press, the shafts cannot be dismantled otherwise. Required here quality training seats. And without solid experience, it is extremely difficult to correctly set the torsion bars and ground clearance.

The role of additional elements

The shock absorber struts in a torsion bar system are very important. Thanks to their device, vibrations of the body, suspension elements and attachments. shock absorber in modern production available in two types: single and double. The characteristics of shock absorbers of each type depend on their design. Automotive shock absorbers depending on working fluid divided into gas, oil and gas-oil. The shock absorber strut support is a device with which the shock absorber itself is attached with the upper part to the car body.

Modern analogues

The torsion beam has now become popular as the rear suspension of front-wheel drive vehicles belonging to the small and medium class. Due to the design, the suspension and the shock absorber with a torsion beam occupy an intermediate position between the dependent and independent type of suspensions, it is this factor that determines its second name - semi-independent suspension.

Tanks are the most famous among Vehicle carriers of torsion suspensions.

Rear beams and shock absorber french cars sometimes they characterize it like that - tank ones, - meaning by this their reliability. They are really reliable, however, they can be reproached with the difficulties of repair and its high cost compared to beams, where the elastic elements are springs.

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