Unit 4 Suspension and Braking System Notes

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Subject - AUTOMOBILE ENGINEERING ME 40041
Branch - Mechanical Engineering
Semester - 4th Semester

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UNIT-IV: SUSPENSION AND BRAKING SYSTEM

In an automobile, the suspension system ensures a smooth and comfortable ride by absorbing shocks, while the braking system ensures vehicle safety by slowing down or stopping the vehicle when required.

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4.1 Suspension System

The suspension system is designed to absorb road shocks, provide stability, and improve ride comfort.

Types of Suspension Systems

1. Dependent Suspension System

   • The wheels on the same axle are connected and move together.

   • Common in trucks and older vehicles.

2. Independent Suspension System

   • Each wheel moves independently, improving ride quality and handling.

   • Common in modern cars.

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4.2 Leaf Spring and Coil Spring Suspension System

(a) Leaf Spring Suspension System

• Construction:

  • It consists of multiple layers of metal strips (leaf springs) stacked together.

• Working:

  • When the vehicle moves over bumps, the springs flex and absorb shocks, reducing their impact on the chassis.

• Used in: Trucks, buses, and heavy vehicles.

(b) Coil Spring Suspension System

• Construction:

  • Uses helical steel springs that compress and expand based on road conditions.

• Working:

  • When the wheel encounters a bump, the spring compresses to absorb the impact, and when the bump passes, it expands to return to its original shape.

• Used in: Cars, motorcycles, and lightweight vehicles.

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4.3 Telescopic Shock Absorber

• Purpose: To control excessive movement of the springs and dampen vibrations.

• Construction:

  • It consists of a cylinder filled with hydraulic fluid and a piston moving inside it.

• Working:

  • When the suspension moves, the piston moves through the hydraulic fluid, creating resistance and slowing down movement, preventing excessive bouncing.

• Used in: Modern cars, bikes, and SUVs.

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4.4 Braking System

The braking system is responsible for slowing down or stopping the vehicle by converting kinetic energy into heat energy.

Functions of Brakes

• To slow down or stop the vehicle.

• To hold the vehicle in place (parking brake).

• To prevent accidents by providing control over speed.

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4.5 Types of Brakes

1. Mechanical Brakes – Operated manually using cables and levers.

2. Hydraulic Brakes – Uses brake fluid to transfer force from the pedal to the brakes.

3. Air Brakes – Uses compressed air (common in heavy vehicles).

4. Electric Brakes – Uses electric motors to slow down the vehicle.

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4.6 Working of Internal Expanding Brake (Drum Brake)

• Construction:

  • Consists of a brake drum, brake shoes, and hydraulic cylinders.

• Working:

  • When the brake pedal is pressed, hydraulic pressure forces the brake shoes outward against the drum, creating friction and stopping the vehicle.

• Used in: Rear wheels of cars, trucks, and motorcycles.

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4.7 Working of Disc Brake

• Construction:

  • Consists of a disc (rotor), caliper, brake pads, and hydraulic system.

• Working:

  • When the brake pedal is pressed, hydraulic pressure pushes the brake pads against the rotating disc, creating friction and stopping the vehicle.

• Used in: Front wheels of most cars, sports bikes, and high-performance vehicles (better cooling and braking efficiency than drum brakes).

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Conclusion

• The suspension system absorbs road shocks and ensures comfort.

• The braking system provides vehicle safety by slowing down or stopping it effectively.

• Leaf spring and coil spring suspensions are widely used in vehicles.

• Disc brakes offer better performance than drum brakes.