Automobile

Understanding Suspension System

The vehicle’s chassis is connected to the front and rear wheels by springs, shock absorbers, and axles. A Suspension system refers to all parts that work together to protect parts from shocks. Springs connect the automotive chassis to the axles in an indirect manner. It is done to protect the body of the vehicle from road shocks caused by bounce, pitch, roll, or sway. These road shocks make for a bumpy ride and put additional strain on the car’s frame and body.

In this article, you’ll get to know the definition, applications, function, components, diagram, types, and working principles of a suspension system.

What is a suspension system?

A suspension system is a set of mechanical connections, springs, and dampers that connect the wheels to the chassis. It has traditionally performed two functions: managing the vehicle’s handling and braking for safety, and keeping passengers comfortable from bumps, vibrations, and other factors. It is a mechanical system of springs or shock absorbers connecting the wheels and axles to the chassis of a wheeled vehicle.

It also aids in maintaining proper vehicle height and alignment. It also controls the vehicle’s orientation and must keep the steering wheel perpendicular to the ground for maximum grip. The suspension also helps to safeguard the car and its contents from damage and wear. The front and rear suspensions of a car may be designed differently.

The suspension system of your car is in charge of smoothing out the ride and keeping the vehicle in control. To offer steering stability and good handling, the suspension system increases the friction between the tires and the road.

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Functions

A suspension system in an automobile serves the following functions:

  • Shock forces are reduced as much as possible
  • Maintain the proper ride height of your car
  • Maintain proper alignment of the wheels
  • Serve as weight support for the vehicle
  • Maintain tire contact with the road
  • Controls the vehicle’s travel direction.
  • To eliminate transmission to car component road shocks.
  • To maintain a solid grip on the road while driving, cornering, or braking.
  • To maintain the correct steering geometry.
  • To achieve a specific body structure and height.
  • Torque and braking reflexes must be resisted.
  • Maintaining vehicle stability while traveling over uneven terrain or turning in order to reduce the tendency for rolling, pitching, or vertical movement.
  • To protect passengers from road shocks and give a comfortable ride.
  • To reduce the strains caused by road shocks on the motor vehicle’s mechanism and offer a cushioning effect.
  • While traveling over tough, uneven terrain, keep the body absolutely level. The up and down movements of the wheels should be proportional to the movement of the body.
  • To protect the vehicle’s structure from stress loading and vibration caused by road surface irregularities while maintaining its stability.
  • To achieve the necessary height for body structure.
  • To retain the right geometrical relationship between the body and the wheels, the body must be supported on the axles.

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Components of a suspension system

Suspension systems have the following components:

Component of a suspension system

Knuckle or Upright:

It is the component of the suspension system that is installed over the wheel’s hub and connects the wheels and the vehicle’s suspension through the linkages provided. A knuckle is equipped with a king-pin and caster angles that assist the vehicle’s front wheels in steering right or left, hence steering the vehicle. The hub of the wheel revolves around the rotation of the wheels, and the knuckle provides housing for the center bearing.

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Linkages:

The rigid connections utilized in a suspension system to connect the mainframe of the vehicle with the knuckle of the wheels using mechanical fasteners are known as links. Wishbones or A-arm, Solid axle or live axle, and Multiple links are the types of suspension that use linkages.

Shock absorbers or Springs:

They are the flexible mechanical components that are put between the linkages (wishbone) to absorb the shock caused by the road condition. Solid axle, multi-links) and the mainframe is designed to reduce road shock before it reaches the vehicle’s mainframe. Out of the various types, spring and damper shock absorber, leaf spring, and air spring are the common types.

Components of a suspension system can be summarized as follows:

  • The shocks from the road surface are neutralized by the use of springs.
  • Dampers, also known as shock absorbers, are used to reduce the free oscillation of springs and so increase riding comfort.
  • The purpose of a stabilizer, also known as a sway bar or anti-roll bar, is to keep the car from swaying to the side.
  • The longitudinal and lateral movements of wheels are controlled by a linkage system that holds the above components.

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Types of the suspension system

The following are the types of suspension systems:

Various types of suspension system

Independent suspension system:

This system means that the suspension is set up so that the wheels on the left and right sides of the vehicle can move up and down vertically independently while traveling over an uneven surface. Because there is no mechanical relationship between the two hubs of the same vehicle, a force exerted on one wheel has no effect on the other. It is used on the front wheels of the majority of vehicles.

Because there is less unsprung weight, this form of suspension usually provides superior ride quality and handling. The fundamental benefit of independent suspension is that it takes up less space, is easier to steer, is lighter, and so on. Independent suspension is exemplified by

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Double wishbones:

It’s an independent suspension system that uses two wishbone-shaped arms to place the wheel (named A-ARM in the US and WISHBONE in the UK). There are two mounting points on the chassis for each wishbone or arm, as well as one joint at the knuckle. The compressing and rebounding wheels’ angle motions can be controlled by utilizing arms of different lengths.

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The fundamental benefit of double wishbone suspensions is that they allow for easy camber, toe, and other characteristics modifications. This style of suspension also allows for increased negative camber gain up to full jounce travel. However, it takes up more room and is slightly more complicated than other systems such as the Macpherson strut. It also provides fewer design options.

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MacPherson Strut:

Earle S. McPherson, the designer of this form of independent suspension, gave it his name. The MacPherson strut is a step forward from the double-wishbone suspension. MacPherson’s key advantage is that all of the pieces that provide suspension and wheel control may be consolidated into a single system.

It simplifies the installation of a transverse engine. Because of its simplicity and inexpensive manufacturing cost, this design is quite popular. The downside is that insulating against road noise is more difficult. A higher strut mount is required for this, which should be as decoupled as possible. In addition, it necessitates a higher clearance height.

Dependent Suspension System

A stiff linkage connects the two wheels of the same axle in Dependent Suspension. A force operating on one wheel will have an effect on the other. Abnormalities harm the connected wheel for each wheel motion produced by road irregularities.

It’s primarily used in big trucks. It can withstand far more shocks than independent suspension. This system is exemplified by

Solid Axle:

A dependent type of suspension is a solid axle or beam axle. It is most commonly utilized in rear wheels with two leaf springs supporting and locating the rear axle. One wheel’s vertical movement affects the other. They’re easy to make and cost a lot of money.

On a complete bump, they are so rigid that there is no change in track width, toe-in, or camber, resulting in low tire wear. The biggest downside is that the beam’s mass is included in the vehicle’s unsprung weight, resulting in poor ride quality. Due to the zero-camber angle, the cornering ability is also weak.

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Semi-independent Suspension System

This form of suspension combines the benefits of both a dependent and independent suspension. In semi-independent suspension, the wheels move relative to one another in the same way as they do in independent suspension, but the position of one wheel has an effect on the position of the other. This is accomplished by the use of twisted suspension parts. A semi-independent example is

Twist Beam:

A torsion-beam axle is another name for the twist-beam suspension. The majority of these are made up of C or H-shaped members. The H-cross shape’s beam connects the two trailing arms and gives roll stiffness to the suspension.

It is mostly utilized in automobiles’ rear wheels. It is particularly advantageous because of its low cost and durability. It has a simplistic design and is quite light. On the other hand, camber angle is limited, and roll stiffness is difficult to achieve. It’s possible that the attributes aren’t appropriate.

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Requirement of a Suspension system

  • Deflection should be kept to a bare minimum.
  • It should be as light as possible.
  • It should be low-maintenance and low-cost to operate.
  • It should have the least amount of tire wear possible.
  • It should have a low start-up cost.

Diagram of suspension system:

diagram of a Suspension System

Working Principle

Working of independent suspension:

Take the suspension of Formula cars, which uses double-wishbone with coil spring suspensions, as an example of how independent suspension works. In Formula cars, independent double-wishbone suspensions are employed, which allow all four tires of the car to move independently of one another, with no relative motion.

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Independent suspension system

Assume the bump is on the vehicle’s left side, and the front left tire comes into contact with it at the same time. When the formula car’s left tire meets a road bump, the front left tire lifts upward; however, because there is no connection between the right and left or front and rear tires, this upward movement is limited to the front left wheel.

The compression-type spring and dampers employed in between the wheel’s knuckle and the mainframe absorb the shock caused by this road bump, either directly or through push roads that transport the shock from the knuckle to the damper. The traction of the formula car’s wheel with the road is maintained by the rigidity of the springs and dampers employed in independent double-wishbone suspension.

Watch the video below to learn more about the working of an independent suspension system:

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Working of Non-independent or Dependent suspension system:

To understand how a dependent form of suspension system works, consider a truck suspension system in India, such as a solid axle or live axle with leaf springs. In trucks, a dependent kind of suspension is used, in which both the rear and front pairs of wheels are attached to a solid axle, causing a small lift in the other when one wheel moves upward.

Dependent Suspension system

The following is the setup for this sort of suspension:

Both the front and rear wheels are attached to the solid live axle, which supports the truck’s chassis. A leaf spring arrangement is employed to dampen the shock between the solid axle and the frame.

Assume the bump is on the truck’s left tire, and the road bump is attempting to lift the truck’s left wheel. When this wheel lifts up due to a road bump, the solid axle attached to it lifts up as well, and the force generated by the wheel as a result of its upward movement is transferred to the corresponding right wheel (as they are both rigidly connected to the live axle), which tries to lift it up slightly.

The leaf springs utilized between the axle and the mainframe alleviate the shock caused by the road bump. When the truck encounters a road shock, the pre-stressed leaf springs attempt to revert to their previous shape, i.e. straighten, which absorbs the road shock.

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Watch the video below to learn how the suspension system works:

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Conclusion

There is no doubt that suspension systems are great components in automobile vehicles. They are a set of mechanical connections, springs, and dampers that connect the wheels to the chassis. Their conventional purpose help manages the vehicle’s handling and braking for safety and to keep passengers comfortable from bumps, vibrations, and other factors. That is all for this article, where the definition, applications, functions, components, diagram, types, and working principle of an automobile suspension system are being discussed.

I hope you get a lot from the reading, if so, kindly share with other students. Thanks for reading, see you around!