Lesson Notes By Weeks and Term v4 - SHS 2
INTRODUCTION TO ENGINE TECHNOLOGY
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INTRODUCTION TO ENGINE TECHNOLOGY
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Subject: Applied Technology
Class: SHS 2
Term: 1st Term
Week: 4
Grade code: 2.1.1.LI.5
Strand code: 1
Sub-strand code: 1
Content standard code: 2.1.1.CS.1
Indicator code: 2.1.1.LI.5
Theme: AUTOMOTIVE TECHNOLOGY
Subtheme: INTRODUCTION TO ENGINE TECHNOLOGY
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Welcome, learners. Today, we are exploring the 'bloodstream' of an engine: the lubrication system. Just as our blood carries nutrients and removes waste to keep us alive, an engine's oil system keeps it running smoothly, preventing it from overheating and destroying itself. Understanding this system is crucial, whether you are driving a car, riding an 'Okada', or operating a generator during 'dumsor'. Knowing how it works can save you thousands of cedis in repair costs and make any vehicle or engine last much longer. We will learn about the different ways engines are lubricated, how the oil is pumped, and how it is kept clean.
A. The Purpose of Engine Lubrication
Before we discuss the *types* of systems, we must understand *why* an engine needs lubrication. An engine has many moving metal parts (pistons, crankshaft, camshaft) that rub against each other at very high speeds. Without a layer of oil between them, the results would be disastrous.
The primary functions of engine oil are: To Lubricate: It creates a thin film between moving parts to reduce friction and prevent wear. Imagine trying to slide a heavy box on a dry floor versus a wet floor. The water acts as a lubricant. To Cool: Oil absorbs heat from hot engine components like the pistons and carries it away to the oil pan (sump), where it can cool down. To Clean: Oil contains detergents that pick up dirt, carbon deposits, and tiny metal particles, carrying them to the oil filter to be trapped. To Seal: It helps to seal the gap between the piston rings and the cylinder walls, which is essential for good compression and engine power. To Prevent Corrosion (Rust): It coats metal parts to protect them from oxygen and moisture, which cause rust. B. Types of Lubrication Systems
There are three main systems used to deliver oil to the engine's moving parts. Mist Lubrication System (or Petroil System) How it Works: This is the simplest system. The lubricating oil is mixed directly with the petrol (fuel) in a specific ratio (e.g., 25:1, meaning 25 parts petrol to 1 part oil). When this fuel-oil mixture enters the engine, the petrol vaporises, leaving behind a fine mist of oil droplets. This mist coats the crankshaft, connecting rod, and cylinder walls, providing lubrication. Where it's Used: Primarily in small two-stroke engines. Ghanaian Examples: 'Okada' motorcycles (especially older models), chainsaws, some outboard motors for fishing boats, and leaf blowers. Advantages: Very simple and cheap to manufacture. No need for an oil pump, filter, or sump. Disadvantages: Provides less effective lubrication compared to other systems. The oil is burned along with the fuel, producing visible blue smoke and more pollution. Forgetting to mix the oil will quickly destroy the engine. Wet Sump Lubrication System How it Works: This is the most common system in passenger vehicles. The bottom of the engine is sealed by a large container called an oil pan or sump, which acts as a reservoir for the oil. An oil pump, located inside the sump, draws oil through a pickup screen and forces it under pressure through internal passages (called oil galleries) to all the critical parts of the engine. After lubricating the parts, the oil simply drips back down into the sump under gravity. Where it's Used: Almost all standard cars, vans, and light trucks. Ghanaian Examples: Toyota Corolla, Hyundai Accent, Nissan Hardbody pickups, Ford Rangers, and most generators ("gen sets"). Advantages: Relatively simple, reliable, and cost-effective. Self-contained within the engine block. Disadvantages: Under extreme conditions (hard cornering, braking, or steep inclines), the oil can slosh away from the pump's pickup tube, causing a temporary loss of oil pressure (oil starvation). The capacity of the oil pan limits the amount of oil the system can hold.