# INTRODUCTION TO TORSION BAR SUSPENSION SYSTEM IN AUTOMOBILE

A torsion bar is a type of suspension system in an automobile is usually used in vehicles such as cars, trucks and vans. A torsion bar suspension system is a significant and acute element of a vehicle’s design. Irrespective of the design, all suspension systems do the same functions. They keep the tires in contact with the surface of the road, upkeep the weight of a vehicle and absorb the forces produced by the movement and motion of the vehicle.

Working Principle Of Torsion Bar Suspension System – Torsion Bar Uses And Advantages

## WHAT EXACTLY IS A TORSION?

Torsion is the twisting of a structural member that is subjected to loads (torque) that cause rotation around the member’s longitudinal axis. Torsion is also referred to as rotational twisting. The member is loaded in such a manner that when the stress is applied, it forms a couple around the longitudinal axis and the reaction is a twisting motion around that axis.

Torque, twisting couples, and twisting moments are all terms used to describe the twisting of a bar.

## TORSIONAL DEFORMATIONS OF CYLINDRICAL BARS

Each cross-section of a circular shaft stays flat and undistorted when the shaft is exposed to torsion. When this occurs, the bar is said to be in pure torsion.

Cross-sections for hollow and solid circular shafts remain plain and undistorted because a circular shaft is axisymmetric.

When noncircular ex. square, rectangular etc.,  (non-axisymmetric) shafts are exposed to torsion, the cross sections of the shafts are deformed.

## WHY TORSION BAR SUSPENSIONS ARE NOT UTILIZED IN TWO WHEELERS?

The reason why it’s not popular is because torsion bars require a specific length to function effectively, and there just isn’t enough space in anything motorbike sized to install a simple and efficient torsion bar suspension.

## WHICH COMPONENT SERVES AS A SPRING IN A TORSION BAR SUSPENSION?

The torsion bar is connected to the chassis of the car at one end and connects to the suspension arm at the other and is coupled to it by a spline or hex as in vintage Chrysler automobiles. Compression of the suspension arm, attempts to twist the bar, which resists, producing the ‘spring’. A torsion bar is simply the cylindrical material of a coil spring that has been straightened out rather than coiled.

## WHAT IS A DEPENDENT SUSPENSION SYSTEM?

A fundamental and early version of the suspension system that has remarkably simple mechanics. This kind features a solid axle connecting both the opposing wheels which enable them to operate as one unit. When one wheel experiences an activity, the other will follow owing to dependence. Widely used in big haul vehicles.

Examples of Dependent Suspension System are: 1. Leaf Spring– The most traditional one. A series of closely packed plates of steel connected to the axle that provides the dampening. Can be utilized transversely or longitudinally. 2. Beam Axle– Popularly found in Front Wheel vehicle. A solid shaft links both the wheels with the inclusion of a track bar. The movement on one wheel produces a response on the other wheel (Beam Axles may be both “live” and “dead” axles).

## WHAT IS AN INDEPENDENT SUSPENSION SYSTEM?

In an Independent Suspension System, each wheel and its connections are not linked in the sense that every component works to the pace of independence. Independent Suspension does not really have a single axle linking each other which allows them to react appropriately to the road circumstances not simply duplicate or alternating the movement of the other wheel.

Independent system is that they create the experience like you are gliding on the road, smooth and jerk-free. Examples of Independent Suspension System are: 1. McPherson Strut often referred to as single Wishbone type. In short, there is a wishbone shaped linkage that gives a mounting point to the axle; A Coil spring is vertically attached to the Chassis of the vehicle. An anti-roll bar is frequently used in such kinds to enhance its stiffness.  This is a common dampening technique used in today’s vehicles such as in General Motors.

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## WHAT IS THE SEMI-INDEPENDENT SUSPENSION SYSTEM?

The midway position between the Dependent and the Independent Suspension as the pseudonym indicate. They function at some degree of independence per wheel which is only constrained to how flexible the connections are. These are used on heavy-duty trucks and other similar vehicles.

Popular instances for Semi-Independent Suspension are: 1. Torsion Bar suspension Type, also known as Twist Beam Axle type. The dampening effect is produced via the twisting and bending of the suspension components under stress. A longitudinal cross beam regulates how each wheel act. It is characterized as a Semi-Independent since the two wheels respond to deflection independently but yet operate in conjunction therefore providing them some semi-balance of independence.

## COMPONENTS OF TORSION BAR SUSPENSION SYSTEM

The key components that constitute the torsion bar suspension system are:

Drive shaft; Lower and Upper shoulder; Shock absorber; Anti-roll bar; Front differential; Subframe.

## HISTORY OF SUSPENSION SYSTEM

History Of Suspension System

## HISTORY OF THE TORSION BAR SUSPENSION SYSTEM

Volkswagen Beetle vehicles were the first to utilize torsion bar suspension, which was introduced in the 1930s. However, this is not completely accurate, since the French fitted a comparable suspension in the Citroen Traction Avant in 1934, which was the first car to do so. Given that the word “twisting” is derived from the French word for “twisting,” it is more than obvious who will take home the title.

As soon as the French and Germans began to use torsion bar suspension systems on the international arena, the Americans went out and began putting the most successful torsion bars on Chrysler automobiles as soon as they were introduced.

In 1938, the Czech engineer Ledwink updated and refined the torsion bar, and Ferdinand Porsche loved his changes so much that he quickly adopted it in large quantities in his vehicle models.

Porsche appreciates ​​the torsion bar’s biggest benefit, namely its lightweight and compactness, characteristics that are particularly sought for in sports and racing vehicles.

When World War II broke out, this kind of suspension was extensively employed in armored vehicles such as the KV-1 and the PANTERA.

Following World War II, virtually all major automobile manufacturers started to include this kind of suspension into some of their models, and the 1950s and 1960s of the twentieth century saw the greatest increase in the use of torsion bar suspensions in automobiles and racing cars. This high level of interest on the part of both manufacturers and car customers may be attributed to the compactness of the torsion system, the cheap installation and maintenance costs, and, most importantly, the long-term reliability of this suspension system, among other factors.

Jaguar’s E-Type was the first car to utilize a torsion bar as a front suspension system, which debuted in 1961. However, with the passage of time and the introduction of new technologies, the torsion bar system started to lose its appeal and popularity. This kind of suspension is much more costly since the production process is very complicated, time-consuming, and expensive.

Today, torsion bar suspension is mostly seen on trucks or SUVs from manufacturers such as Ford, Dodge, Mitsubishi Pajero, General Motors, and others.

## SUSPENSION SYSTEMS ARE REQUIRED IN AUTOMOBILES FOR THE FOLLOWING REASONS

1. To absorb shocks and vibration produced by road imperfections.

2. For the purpose of transferring vehicle load to the wheels (Supporting the weight)

3. For the purpose of ensuring the vehicle’s stability (contact of the wheels to ground)

4. To provide passengers with cushioning and riding comfort throughout their journey.

5. To avoid the occurrence of body squats and body dives.

## SUSPENSION SYSTEMS HAVE THE FOLLOWING FUNCTIONS

1. To protect people and cargo from the effects of road shocks

2. In order to maintain the stability of vehicles while in motion (pitching or rolling)

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3. It is necessary to keep the wheels in constant contact with the road when driving and performing maneuvers such as turning and braking.

4. To keep the steering geometry in correct alignment.

5. To offer appropriate riding and cushioning characteristics

6. To allow for fast cornering without excessive body roll; and

7. To avoid excessive body squats or body dives while cornering.

## CONSTRUCTION AND WORKING OF A TORSION BAR SUSPENSION SYSTEM

Torsion bar suspensions are basically metal bars that perform the role of a spring. At one end, the bar is fixed rigidly in place to the chassis of a vehicle. The last end of the bar may be fastened to the axle, suspension arm, or a spindle, depending on the vehicle’s design. For instance a vehicle travels alongside the road, the forces made by the motion of the vehicle produce torque on the bar, which turns it along its axis.

Counteracting the torque is the fact that the torsion bar obviously wants to resist the twisting effect and return to its normal state. By doing so, the suspension supplies a level of resistance to the forces generated by the movement of the vehicle. This resistance is the basic principle behind a torsion bar suspension system.

Torsion Bar Mounting In Chassis – Components Of Torsion Bar Suspension System

## WORKING OF TORSION BAR SUSPENSION SYSTEM

Torsion bars use the twisting properties of a steel bar to offer coil-spring-like functions. One end of a bar is fixed rigidly to the vehicle frame. The further end is fastened to a wishbone, which acts like a lever that travels perpendicular to the torsion bar. When the wheel hits at a stone or projections, vertical motion is shifted to the wishbone and then, through the levering act, to the torsion bar. The torsion bar then twists sideways its axis to offer the spring force. European car manufacturers used this system widely, as did Packard and Chrysler in the United States, through the 1950s and 1960s.

Working Principle Of Torsion Bar – Function Of Torsion Bar – Function Of Twist Beam Suspension System

## ADVANTAGES OF TORSION BAR SUSPENSION SYSTEM

In this system there are several key advantages. The design of the torsion bar suspension takes up less area than other suspension systems. This makes the vehicle designers to create a more spacious passenger compartment. The elevation of the bars can also be varied more easily than other suspension systems. They are also extremely durable and habitually have a long service life.

Torsion Bar Tools

## DISADVANTAGES OF TORSION BAR SUSPENSION SYSTEM

There are also several disadvantages of torsion bar suspensions. The main disadvantage is that these bars generally do not offer what is known as a progressive spring rate. Generally in suspensions with a progressive spring, the coils of the spring are spaced at dissimilar distances from each other. This permits the suspension system to aids braking, firm steering and handling, although providing for a smooth and comfortable journey. Vehicles with torsion bars are repeatedly tuned to either provide a more firm driving experience at the expense of ride smoothness, or a smoother ride at the expense of the vehicle’s handling quality.

## RECENT TRENDS IN TORSION BAR SUSPENSION SYSTEMS

Vehicle With Best Suspension – Good Suspension System Of A Vehicle – Torsion Beam Suspension – Torsion Bar Assembly For Vehicle Suspension System

Torsion bar suspension systems were once relatively common in passenger vehicles, but today are used mainly for the suspension systems of trucks and sport utility vehicles. Some famous automobiles that used this type of suspension were the original Porsche 356, Volkswagen Beetle, Porsche 911 models that utilized an air-cooled engine, and significantly of the Chrysler line-up of cars from the late 1950s through the late 1980s.

Compared to multi-link suspensions, torsion beams are generally mechanically simpler, may be lighter and are usually easier to package. This is a highly significant advances, especially in the field cargo space. Torsion beams typically sit lower in a car, something that frequently provides for additional trunk space. This is likewise true with the Mazda3 in 2020. The redesigned compartment is deeper and more versatile than previously. One of the greatest issues with torsion is unsteady driving while cornering. Driving a vehicle with torsion in quick bends needs a lot of attention and expertise on the side of the driver. Another drawback are extra vibrations which are conveyed when the vehicle stops. These vibrations are particularly severe towards the back of the vehicle, and this does not help at all to the comfort of passengers in the rear seats. However, this type of torsion bar suspension system is frequently utilized on popular SUVs and it serves as a front suspension.

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## FAQ’s:

### The purpose of a suspension damper is to

b. Reduce the bumb stroke of the spring

c. Absorb the energy stored in the spring

d. All the above

a. U-bolt

b. Spring clip

c. Centre bolt

d. Shackle pin

### Why a laminated spring is made up of a series of leaves is to

a. Reduce inter leaf friction

b. Soften the spring action and increase the maximum deflection

c. Allow the leaves to slide during the bumb movement

d. Overcome the weakness at the centre of a single leaf spring

Answer: d. Overcome the weakness at the centre of a single leaf spring

### In case of clutch if the spring is becomes weak, the remedy lies in

a. Tightening further the springs

b. Interchanging the springs

c. Retempering the springs

d. Replacing the springs

### The stabilizer bar reduces the tendency of the vehicle to roll when

a. Taking turn

b. In straight

c. Normal condition

d. High speed

a. Caster angle

b. Toe in

c. Toe out

d. Camber angle

### Which of the following are advantages of independent suspension system

a. Elastic strain energy stored in a coil spring is greater

b. Un sprung weight is reduced

c. Softer spring can be used without increasing rolling effect

d. None of these

Answer: a. Eleastic strain energy stored in a coil spring is greater

### Another name for a shock absorber is __________

a. Damper

b. Torsion bar

c. Spring

d. Independent suspension