A car’s suspension system connects the chassis to the wheels using springs, shock absorbers, and axles to protect the vehicle from shocks and provide a smooth ride.
It absorbs bumps and road irregularities to maintain good handling and control while protecting the car’s body from strain.
The system is like a lattice of dampers and springs that absorb shock to ensure a secure and comfortable drive.
What is a suspension system?
A car’s suspension system consists of mechanical connections, springs, and dampers that connect the wheels to the chassis.
It serves two main functions: managing the vehicle’s handling and braking for safety, and keeping passengers comfortable by absorbing bumps and vibrations.
The system also helps maintain proper vehicle height and alignment, controls the vehicle’s orientation, and safeguards the car from damage and wear.
The front and rear suspensions of a car may be designed differently to smooth out the ride and improve steering stability and handling by increasing friction between the tires and the road.
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 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.
Components of a suspension system
Suspension systems have the following components:
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 kingpin 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.
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 absorbers, leaf springs, and air springs are the common types.
The 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 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.
Types of the suspension system
The following are the types of suspension systems:
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 does not affect the other. It is used on the front wheels of the majority of vehicles.
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.
The fundamental benefit of double wishbone suspensions is that they allow for easy camber, toe, and other characteristic modifications.
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.
Dependent Suspension System
A stiff linkage connects the two wheels of the same axle in Dependent Suspension. A force operating on one wheel will affect 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.
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 affects 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, the camber angle is limited, and roll stiffness is difficult to achieve. It’s possible that the attributes aren’t appropriate.
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.
Working of independent suspension:
Formula cars use independent double-wishbone suspensions, allowing each tire to move independently. When a bump is encountered, only the affected tire is impacted due to the lack of connection between tires.
Compression-type springs and dampers absorb the shock, maintaining traction with the road.
Working of Non-independent or Dependent suspension system:
In a dependent suspension system used in truck suspension systems in India, both front and rear wheels are attached to a solid live axle, causing a small lift in the other when one wheel moves upward.
The solid axle supports the truck’s chassis, and a leaf spring arrangement dampens the shock between the axle and the frame.
When one wheel lifts due to a road bump, the corresponding wheel connected to the live axle also tries to lift, and the shock is absorbed by the leaf springs attempting to revert to their previous shape.