Lesson Notes By Weeks and Term v4 - SHS 2
INTRODUCTION TO VEHICLE TECHNOLOGY
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INTRODUCTION TO VEHICLE TECHNOLOGY
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Applied Technology
Class: SHS 2
Term: 1st Term
Week: 8
Grade code: 2.1.2.LI.3
Strand code: 1
Sub-strand code: 2
Content standard code: 2.1.2.CS.1
Indicator code: 2.1.2.LI.3
Theme: AUTOMOTIVE TECHNOLOGY
Subtheme: INTRODUCTION TO VEHICLE TECHNOLOGY
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Every day in Ghana, we travel on roads that can be smooth or very bumpy. Have you ever wondered why the ride in a Toyota Vitz feels different from the ride in a Ford Transit 'trotro', especially when you hit a pothole on the Accra-Kumasi highway? The reason is the suspension system. This system is the set of components that connects the wheels of a vehicle to its body. Its job is to keep you comfortable by absorbing shocks from the road and to keep you safe by ensuring the tyres stay in firm contact with the ground for proper steering and braking.
A. Purpose of a Suspension System
A vehicle's suspension system has two primary jobs: Passenger Comfort (Isolating from road shock): It absorbs the energy from bumps, potholes, and uneven surfaces, preventing the shocks from being transferred to the vehicle's body and its occupants. This provides a smooth ride. Vehicle Control and Safety (Maximising grip): It keeps the tyres pressed firmly onto the road surface. This continuous contact is crucial for effective steering, braking, and acceleration, especially when cornering or on a rough road. B. Main Components of a Suspension System
Every suspension system is made of several parts working together. The main ones are: Springs: These are the heart of the system. They absorb the initial shock from a bump by compressing or flexing. They hold the vehicle's weight. The three main types are leaf, coil, and air. Shock Absorbers (or Dampers): Springs are good at absorbing energy, but they tend to bounce up and down after being compressed. Imagine dropping a spring on the floor – it keeps bouncing. The shock absorber's job is to stop this bouncing. It's a hydraulic (oil-filled) piston that resists motion, quickly settling the vehicle after a bump. A car with bad shock absorbers will feel "floaty" and continue to bounce long after hitting a pothole. Control Arms (or Wishbones): These are strong links that connect the wheel hub (where the wheel is mounted) to the vehicle's frame or chassis. They allow the wheel to move up and down while preventing it from moving forwards or backwards. Bushings and Ball Joints: These are the "joints" of the suspension system. Bushings are rubber or polyurethane pads that act as cushions at the connection points of control arms, reducing vibration and noise. Ball joints are like the human shoulder joint, allowing for both pivoting and turning motion, which is essential for steering. C. Layouts of Suspension Systems
The way these components are arranged is called the layout. There are two main layouts. Dependent Suspension System (Solid Axle / Beam Axle) Description: In this layout, the two wheels on an axle (e.g., the two rear wheels) are connected by a solid metal beam or housing. This means the movement of one wheel directly affects the other. If the right wheel goes over a bump and moves up, the solid axle will tilt, causing the left wheel to also change its angle relative to the road. Analogy: Imagine holding a broomstick with a wheel at each end. If you lift one end, the other end is also affected. Where it's found: Almost always on the rear of heavy-duty vehicles like: Ford Transit and Mercedes Sprinter ('trotros') Toyota Hilux and Ford Ranger (pick-up trucks) MAN Diesel and Kia Rhino (cargo trucks) Advantages: Strong and Durable: Simple design can handle very heavy loads. Inexpensive: Fewer parts make it cheaper to manufacture and repair. Constant Camber: The wheels remain perpendicular to the axle, which is good for tyre wear under heavy loads. Disadvantages: Poor Ride Comfort: A bump on one side of the road is felt on the other side. Heavy: The solid axle adds a lot of unsprung weight (weight not supported by the springs), which harms handling. Independent Suspension System Description: In this layout, each wheel on an axle is attached to the chassis independently. The movement of one wheel does not directly influence the other. If the right wheel hits a bump, it can move up and down on its own, while the left wheel remains unaffected. Analogy: Think of your two arms. You can raise one arm without the other one moving. Where it's found: Almost always on the front wheels of all modern cars, and on both front and rear wheels of most passenger cars like: Toyota Corolla/Camry Honda Civic/Accord Kia Cerato Hyundai Elantra Advantages: Superior Ride Comfort: Bumps are absorbed by each wheel individually, leading to a smoother ride. Better Handling and Stability: The wheels can maintain better contact with the road during cornering and on uneven surfaces. Lighter: Less unsprung weight improves road holding. Disadvantages: More Complex: Many more parts (control arms, joints, bushings) are needed. More Expensive: Higher manufacturing and maintenance costs. Less Robust: Not as suitable for carrying extremely heavy loads as a dependent system. D. Types of Springs Leaf Springs Construction: Made of several layers of long, flat steel strips (called "leaves") of varying lengths, bundled together. The longest leaf, the "master leaf," is bent at the ends to form eyes for mounting to the vehicle frame. How it works: When the wheel hits a bump, the entire stack of leaves flexes upwards, absorbing the energy. Its own internal friction helps to dampen the bouncing effect slightly. Commonly used with: Dependent suspension systems. Ghanaian Context: Look under any pick-up truck, 'trotro', or cargo truck in Ghana, and you will see leaf springs at the rear. They are perfect for the heavy loads these vehicles carry. Advantages: Very strong, simple, and can support heavy loads. Disadvantages: Provide a stiff, often harsh ride; they are heavy. Coil Springs Construction: A heavy-duty steel bar twisted into a helix or coil shape. How it works: It absorbs bumps by compressing and expanding. It stores energy when compressed and releases it when it expands. It cannot support side-to-side or front-to-back forces, so it must be used with control arms. Commonly used with: Independent suspension systems (and some dependent systems on cars). Ghanaian Context: This is the most common spring found on saloon cars and SUVs like the Toyota RAV4 or Honda CR-V that are used for personal transport. Advantages: Provides a much smoother and more comfortable ride; they are compact and lightweight. Disadvantages: Cannot support heavy loads by themselves; require a more complex system of control arms. Air Springs (or Air Suspension) Construction: A tough rubber and fabric bag or bellow, which holds pressurised air. It is connected to an onboard air compressor and a reservoir. How it works: The air inside the bag acts as the spring. An electronic control system can add or remove air from the bag via the compressor to change the spring's stiffness or adjust the vehicle's ride height. Commonly used with: Independent suspension systems. Ghanaian Context: Found on high-end luxury vehicles (e.g., some models of Mercedes-Benz S-Class, Range Rover, Toyota Land Cruiser) and large inter-city passenger coaches (e.g., VVIP, STC, OA buses) for maximum passenger comfort. Advantages: Excellent ride comfort; adjustable ride height (can be raised for rough roads); can adapt to changing loads automatically. Disadvantages: Very complex and expensive to buy and repair; potential for air leaks can leave the vehicle stranded.