A torsion beam is a type of suspension in which a torsion bar plays the role of an elastic element. A torsion bar is a metal elastic element that works on twisting. This element, as a rule, consists of a set of rods, plates or beams of a certain section. The torsion bar is attached at one end to the guide element - and at the other - to the frame or car body. Thanks to the torsion bar, an elastic connection is achieved between the body and the wheel. Torsion bars are used in various types suspension: trailing arms, double suspension wishbones and so on. A similar principle has found application in the design of the torsion beam (suspension with interconnected levers of the right and left wheels). Due to the strong connection between the wheels most widespread design found in the rear suspension front wheel drive vehicles. Today we can safely say that the suspension rear wheels based on a torsion beam - the most common design.
Torsion beam - a hollow steel part of complex configuration, rigid in bending, but pliable in torsion. This allows the wheels to move up and down independently of each other. The torsion beam is attached to the body, as a rule. The rigidity of the beam itself in the transverse direction must ensure a constant distance between the wheels. Additional elastic elements in torsion beam suspensions are most often springs.
The history of the creation and development of the torsion structure
The prototype of the current beam is a torsion bar - a device that was first used in the 30s of the twentieth century. Further improvement torsion bar suspension were engaged - the Czech professor Ledvinka and the German inventor Ferdinand Porsche, who first adapted it for mass production.
Enough wide application on small cars torsion bars were received in the 50-60s of the last century. The reason for the interest in the device is the relative ease of manufacture and compactness of these elements. Longitudinal swing arms were attached to the ends of the torsion bar, which were connected to knuckle using ball bearings or a pivot assembly.
On the Zaporozhets car, two square-section torsion bars were used as the front suspension, which consisted of steel pipes located one above the other, longitudinal suspension arms were attached to the ends of the pipes. The author of this design was the same.
The device and principle of operation of the torsion beam
The guiding device of the suspension with a torsion beam are two trailing arms, which are rigidly connected to each other by a beam. On the one hand, the trailing arms are attached to the wheel hubs, and on the other - to the body. The torsion beam has a U-shaped section, due to which it has low torsional rigidity and high bending stiffness. This property allows the wheels to move up and down independently of each other.
On modern cars torsion beam may be transverse or longitudinal. The transverse arrangement is used on passenger cars mobiles. And the longitudinal layout is characteristic, mainly, of large and heavy trucks. In both variants, the torsion bar suspension provides optimal wheel and body damping, ensures a smooth ride and regulates body roll when cornering.
On some vehicles, torsion bar suspension may be used in combination. Depending on the state pavement and speed of movement, this electric motor tightens the beams to obtain the necessary rigidity.
Pros and cons of a torsion beam
The main advantages of torsion bar suspensions in general are compactness in the width of the car, ease of height adjustment ground clearance, small total weight and, of course, durability. Torsion bar suspensions are very easy to maintain and operate. Such suspensions are much easier to adjust than spring ones. From a manufacturer's point of view: A torsion beam is cheap to make and easy to install on a machine on assembly lines.
One of the most significant shortcomings: additional vibrations transmitted from the wheels to the body, contributing to low comfort for rear seat passengers. And as a result, which negatively affects when traveling long distances.
Operational Issues
If the torsion bar suspension on the car is loose, then you can adjust its position with a simple wrench. To do this, you need to get under the car and tighten the loose bolts. The main thing is not to overdo it, because overtightened bolts when the car is moving will cause excessive rigidity.
Modern cars are very different from those that were common when our parents were young. However, the main elements of the design have been preserved. They have only been upgraded to the point where they are ready for normal daily operation. An example is a suspension.
Today you can find car models with air or spring suspension, as well as those that operate the spring type of suspension. But, the topic of our conversation today will be what is it and how does a torsion bar suspension work.
Torsion bar suspension on a real car
General terms
A torsion bar suspension is a name given to special torsion-type metal shafts that work in torsion.
One of their ends is fixed to the chassis, while the other is mounted on a lever, which is fixed completely perpendicular, and is connected to the axle. The suspension of the type in question is made of steel, which has been pre-treated in the appropriate temperature regime. Due to this, during torsion, the suspension is able to withstand significant loads. In fact, the main principle of operation of this suspension can be considered the effect on bending.
As a rule, the torsion beam is located longitudinally or transversely. If we are talking about the longitudinal type of placement, then it is used on large cars. Most often, we are talking about trucks, which provide for a significant load on undercarriage. And here cars, basically, they use the transverse arrangement of this suspension, and even on the rear-wheel drive.
This suspension is also found on other vehicles.
But, in both cases, such a suspension helps to provide a fairly smooth movement, as well as to regulate the roll when cornering. This ensures the maximum value of vibration damping, both for the wheels and for the body. In addition, the oscillation of the wheels, which are in this case manageable.
Some car models use a torsion bar suspension in order to carry out automatic leveling by means of a motor. He, as it were, pulls together the beams, giving additional rigidity. Specific efficiency is determined by the speed of movement and the condition of the road.
Suspension, which can be adjusted in height, can be used during wheel changes. The fact is that the car or other vehicle is raised by three wheels, while the fourth wheel will be raised without the help of a jack.
The advantage of torsion bar suspension
Like any technology, torsion bar suspension has its advantages. We are talking about the fact that the operation of cars with this type of suspension is one of the longest. This is the result of how the torsion bar suspension is designed.
Height adjustment
In addition, you can adjust the height very easily. And compactness in width will serve well, as automotive manufacturers, and those who will be engaged in the direct maintenance of the car.
Space saving
A suspension of this type, as a rule, takes up much less space than a spring suspension, which is called MacPherson strut. And, of course, it is important to remember that the torsion bar suspension is one of the easiest to operate and maintain.
Schematic representation of a torsion bar suspension
In a situation where such a suspension is loose, then it can be adjusted very simply. To do this, use a regular wrench. You only need to get under the car to tighten the necessary bolts. But, here you need to remember that excessive tightening of the bolts is fraught with a very hard ride of the car in the future. This is the main pros and cons of the torsion bar suspension.
But what is torsion?
Now you need to figure out what this torsion bar is, which became the basis of such a popular suspension. In fact, this is just an elastic element made of metal, which, as we have already said, works on twisting.
Basically, this is a metal rod that has a circular cross section with a special spline type connection at its ends. In some cases, the torsion bar may consist of a set of plates and rods, as well as a beam that has the desired cross section.
And this is what the torsion itself looks like
The appearance of the torsion bar from the car Mitsubishi Pajero
Very important feature torsion bar can be considered that it can be used to adjust the height of the body. Of course, in high-tech cars this parameter can hardly be called very important, but many classic vehicles, as well as those cars that are designed to provide the ability to travel in the most difficult conditions are making good use of this opportunity.
Speaking about the torsion beam, which occupies a special place in the design of the suspension, it must be said that a pair of trailing arms, which on the one hand are attached to the body, and on the other - to wheel hubs. The beam itself has a U-shaped section, so you can count on maximum rigidity and strength. The bending strength will be stronger than the torsion strength. Therefore, the wheels can move vertically independently of each other.
A short video explaining what a torsion bar suspension is:
In the designs of modern independent suspensions, along with a spring or an air spring, a torsion bar (torsion - torsion, translated from French) can also be used as the main elastic element. The torsion bar suspension provides the car with a number of advantages, the main of which are high smoothness and compactness of the suspension. However, her significant shortcomings in the form of worse handling and rollability of the car, they do not allow the use of torsion bars in the bulk of modern passenger cars.
History of appearance
Torsion bar suspension has been used since the mid-1930s on cars. french brand Citroen. In the 1940s, torsion bars were used on racing cars Porsche.
Legendary french car Renault 16 with torsion bar suspension
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.
What is a torsion?
The torsion bar device is a metal shaft or rod that twists in one direction. In cross section, the torsion bar can be round or square, less often lamellar - consisting of several layers working together in torsion.
Elastic element of the torsion bar suspension with fasteners One of the ends of the torsion bar is rigidly attached to the carrier suspension arm by means of a spline connection, the other is similarly fixed to the car body or frame. The axis of rotation of the lever and the axis of twisting of the torsion bar are on the same line. With a calculated resistance to twisting under load, the torsion bar supports the weight of the car and provides an effective elastic connection between the suspension and the body when the lever is moved. The principle of operation of the torsion bar is also used in the stabilizer roll stability with opposite travel of the suspension of one axle.
Round torsion shafts The steel alloy from which the torsion bar is made has high performance elasticity and endurance, able to withstand prolonged loads without deteriorating its properties. The length and thickness of the shaft also affects the performance and softness of the suspension. To protect against rust and destruction, the surface of the torsion bar is coated with a special anti-corrosion compound or a rubberized coating.
The principle of operation of the torsion bar suspension
Torsion bar suspension works similarly to spring, spring or air. A steel rod - a torsion bar - acts as a spring element. When the suspension is working, the force from the carrier arm is transmitted to the torsion bar, causing the rod to twist up to a certain limit. After that, the elastic element returns to its original state, aligning the position of the lever.
Types of torsion suspensions
Front independent torsion bar suspension on wishbones
The device and principle of operation of the torsion bar suspension 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.
- Damping element - which performs the function of damping vibrations.
- compensating for body roll while driving.
Independent front double wishbone torsion bar suspension Toyota Hilux Surf 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 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.
Rear suspension with transverse torsion barsfeature elastic elements rear suspension there 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
Rear semi-independent U-shaped 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 rear axle most budget front-wheel drive cars.
Let's define what is car suspension. This is a device that provides elastic coupling car wheels with a carrier system, as well as regulating the position of the body when driving, reducing the load on the wheels.
Currently offered Various types suspensions: spring, pneumatic, spring, torsion, etc. So, the torsion type is torsion shafts made of metal that work in torsion, with one end attached to the chassis, the other to a special lever standing perpendicular and connected to the axle.
The manufacture of such a part is made of heat-treated steel, which directly allows to withstand heavy loads at the moment of rotation.
The main principle of the suspension is bending work.
Application of the torsion model
The location of the torsion beam is possible longitudinally and transversely. The longitudinal arrangement is used on large, heavy trucks. On passenger cars, a transverse arrangement is used, usually on a rear-wheel drive.
In these two cases, the mechanism is designed to ensure smooth running, control roll when turning, ensure the optimal damping of vibrations of the wheels, the body, and reduce vibrations of the steered wheels.
For some vehicles, torsion bar suspension is used for automatic leveling, using a motor to tighten the beams for added rigidity, depending on speed as well as road surface conditions.
Adjustable height design can be used when changing wheels. This is when the vehicle is lifted with the help of three wheels, and the 4th is raised with the help of a jack. The main advantage of this type of suspension is durability, ease of height adjustment, as well as compactness in the width of the vehicle.
It takes up much less space than spring hangers. Of course, the torsion bar configuration is easy to operate and also easy to maintain.
Work process
From this video, you will learn how the torsion bar suspension works.
Thanks to torsion shaft it is fixed rigidly on the body or frame of the car; during the operation of the suspension, twisting forces act on it. But the torsion shaft is made of a special alloy and has a certain hardening, which allows it to work as a spring element.
At the moment of twisting, the shaft tends to return car wheel to original position. So, the principle of operation is similar to a spring or sprung version of this auto part. Semi independent suspension is a suspension system made in the form of two longitudinal levers connected by a cross member of the longitudinal levers.
The main advantages of such a mechanism:
- ease of installation;
- light weight;
- compactness.
The key disadvantage is the possibility of application only on a non-driving axle.
suspension adjustment
In the case of a loose suspension, it is possible to adjust the positions using an ordinary wrench. It is enough to get down the car, tighten the necessary bolts. The main thing is not to overdo it in order to avoid excessive rigidity of the stroke at the moment of movement. Torsion parts are easier to adjust than spring types.
Car manufacturers are changing the torsion beam to control the position of the movement, depending on the weight of the engine.
Key repair properties
Considering all the problems of torsion beams, it is quite possible to conclude that maintenance, as well as repair of a torsion bar suspension, is associated with such situations:
- Structure height adjustment.
- Dismantling or replacement of torsion bars.
- Replacing needle bearings.
- Replacement of pins, axles of the rear beam.
- Repair of rear beam levers.
Adjusting the height of the rear suspension should not be considered as a repair of the entire structure. This usually happens due to the fact that the owner of the car wants to raise back auto.
Sometimes a change in the height of the beam is provided in order to increase rigidity and reduce the draft of the car rear, while maximum load. You need to know that the rear beam torsion bar is not able to work when the height of the rear beam changes, it will be operated under a more aggressive load, and this may affect its resource.
The process of changing the height consists in changing the position of the torsion bar, or rather its splined end, as well as the sprocket. The torsion bar has slotted connectors at the ends. The torsion bar is attached at one end to the slotted connector, the rear beam lever.
And others - in the slot on the beam body. If repairs are being made of this type suspension, then you need to dismantle the torsion bars.
In this situation, it is important to make the native position of the torsion bars in the rear beam, so that at the time of installation it is clear what and where it is inserted. In order to dismantle the torsion bar in the process of tightening from the spline connection, an inertial puller is used.
The puller pin is screwed into the thread on the end of the torsion bar, maybe this thread should be cleaned.
Often, spline connections “sour” or “stick”, in this case, a standard puller will not help, only an ordinary sledgehammer can help out.
Often torsion bar suspension repair is associated with the process of replacing the needle bearings of the rear beam. According to some data, the process of replacing needle bearings is needed after 80,000 km of run.
When replacing bearings, it will be necessary to dismantle the torsion bars, as well as the beam levers. Each side of the beam contains two bearings. The most dangerous problem of the rear beam is the wear of the needle bearing, because it is difficult for an ordinary motorist to determine this.
In the absence of diagnostics, the car is also operated with a crumbled bearing, thereby exacerbating the problem. As a result, the axle wears out. Of course, it is possible to replace the axles of the rear beam, but this is very difficult in "home" conditions, since in addition to knowledge and experience, special equipment and fixtures.
Stations Maintenance will not replace the axles, but only offer a new beam assembly with new axles, and this is a very expensive proposition.
The most severe case in the repair of a torsion-type structure is the destruction seat bearing in the lever. This happens rarely, in a very "neglected" situation.
The destruction of the seat occurs for the reasons that the pin of the rear beam, although much less often, since this place is protected by the outer race of the bearing. Lever repair process: restoring a seat on metal-cutting equipment.
The main problem of restoring the beam arm is finding the required equipment, such work is carried out on a boring and turning machine.
Gallery
In this section, there are photos of torsion bar suspensions for a tank, trailer and others.
If you are going to buy a car, you should find out the pros and cons of a torsion bar suspension in order to decide whether to choose a car with this type, or turn your attention to more traditional equipment. The installation of a torsion beam among the French is especially popular - almost all Renault models, Peugeot and Citroen are equipped with it.
Often this mechanism is even called a French beam, although it is based on an idea first embodied in a car. Volkswagen Beetle (and this happened in the 30s of the last century), and the Czech Ledvinka and the German Ferdinand Porsche improved the detail. The main part in the suspension is the torsion bar. It is an elastic segment made of metal, designed to work on twisting.
Most often, a torsion bar is a round rod part with spline connections at the end, however, it can be made from a beam or a collection of special plates. On one side, the mechanism is attached to the car body or car frame, and on the other, to the lever. In motion, the torsion bar twists, which tightly binds the wheels to the body. The torsion beam can be oriented along the axis of the vehicle (this option is used in heavy trucks), and maybe a transverse one - this is exactly what is mounted on cars, and mostly rear-wheel drive ones.
The pros and cons of the torsion bar suspension are due precisely to the peculiarities of its structure. Let's take a closer look at the advantages and disadvantages of such a mechanical design, which has already become quite familiar and used in many cars.
What do we have on the plus side?
The main gain is in the compactness of this type of assembly. Due to the small dimension, it becomes possible to build quite big trunk and provide enough space to accommodate rear passengers- that is, space is added. A very valuable quality is also the dependence of the stiffness of the suspension on the size of the torsion bar: the longer it is,. In addition, the adjustment for hardness / softness is very simple and feasible even on your own at home, so to speak, conditions.
There is even the possibility of some clearance adjustment. The redistribution of the dynamic load from the track over the entire frame of the car increases its stability and makes the car more obedient to drive and operate. In maintenance and repair, a torsion bar suspension is (in most cases) simpler and cheaper than a spring one. Its total weight is again much less than that of the traditional one, which has a good effect on the economy of the ride and the service life of the entire car (a resource is added). In the opinion of the manufacturer, the advantage of the torsion bar suspension is in its not too expensive manufacture and practical ease of installation.
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What went down?
However, no device, as a rule, can be perfect and ideal. Even the most successful engineering ideas have some unpleasant sides. In the torsion bar suspension, experts found the following, not entirely pleasant shortcomings:
- The most basic and noted minus is shaking on back seat. Additional vibrations go to the body, which are felt very well by all passengers behind;
- High-quality sound insulation cannot be achieved even with additional measures - all for the same reason that people behind are not too comfortable;
- You will have to drive more carefully and carefully: the presence welds and, accordingly, the presence of voltage in them limit the maximum permissible load for suspension;
- Torsion bars tend to burst like springs. But they still cost much more significantly;
- The low cost of repairs with maintenance can also become very relative. It already depends on design features each model. If for repair work it will be necessary to dismantle the entire beam when replacing the torsion bar (and enough models are designed in this way), then the bill for the services will be quite substantial. If you are given the opportunity to get close to the replacement part without global dismantling, then yes, the price will be lower than for similar work with a spring suspension.
