Lesson Notes By Weeks and Term v4 - SHS 2
INTRODUCTION TO ENGINE TECHNOLOGY
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INTRODUCTION TO ENGINE 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: 3
Grade code: 2.1.1.LI.4
Strand code: 1
Sub-strand code: 1
Content standard code: 2.1.1.CS.1
Indicator code: 2.1.1.LI.4
Theme: AUTOMOTIVE TECHNOLOGY
Subtheme: INTRODUCTION TO ENGINE TECHNOLOGY
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The engine is the heart of any vehicle, generator, or even some farming equipment like a corn mill engine. Just like the human body needs blood to function, an engine needs oil. The system that circulates this vital oil is called the lubrication system. In Ghana, where vehicles like trotros, taxis, and okadas are essential for daily life and often operate under harsh conditions (heat, dust, traffic), understanding the lubrication system is crucial. A failed lubrication system can destroy an engine in minutes, leading to expensive repairs and loss of income. This lesson will break down how this system works, its parts, and why it is the key to a long and healthy engine life.
This section contains the core content for the lesson. It is designed to be delivered directly to the learners. A. The Purpose of the Lubrication System
Before we look at the parts, we must understand *why* an engine needs lubrication. An engine has many metal parts moving against each other at very high speeds. Without oil, the friction would create so much heat that the parts would melt and fuse together, a catastrophic failure called 'seizing'.
The lubrication system performs four critical jobs. A good way to remember them is CCCC: Cools: Oil absorbs heat from hot engine parts like the pistons and bearings and carries it away to the oil sump, where it can cool down. It acts like a liquid cooling agent. Cleans: As oil circulates, it picks up tiny particles of metal, soot (from combustion), and dirt. It carries these contaminants to the oil filter, which traps them, keeping the engine clean. Cushions: The oil forms a thin, protective film between moving parts. This film acts as a cushion, absorbing shocks and preventing direct metal-to-metal contact, which reduces wear and noise. Think of the crankshaft spinning on its bearings – it's actually floating on a film of oil. Seals: The oil helps to form a seal between the piston rings and the cylinder wall. This prevents combustion gases from leaking past the pistons (a condition called 'blow-by') and ensures maximum power is generated. B. The Main Parts of a Pressure-Fed Lubrication System
This is the most common type of lubrication system found in cars, trotros, and trucks in Ghana. Oil Sump (or Oil Pan) What it is: A metal pan bolted to the bottom of the engine block. Function: It is the reservoir or storage tank for the engine oil. It is designed to hold several litres of oil and helps in cooling the oil as air passes over its surface while the vehicle is moving. Ghanaian Context: When a mechanic ("fitter") says they are going to "drain the oil," they unscrew a drain plug at the bottom of the oil sump. Oil Pickup Tube and Strainer What it is: A tube that extends from the oil pump down into the oil sump. Its opening is covered by a wire mesh screen (the strainer). Function: It is the entry point for the oil into the system. The strainer is a basic filter that prevents large pieces of debris or sludge from being sucked into the oil pump. Oil Pump What it is: The heart of the lubrication system. It is usually driven by the crankshaft or camshaft. Function: It is a mechanical pump that sucks oil from the sump (via the pickup tube) and forces it under pressure through the rest of the engine. Without the pump, the oil would not circulate. Pressure Relief Valve What it is: A spring-loaded valve, often located in or near the oil pump. Function: It acts as a safety device. If the oil pressure gets too high (e.g., when the engine is cold and the oil is thick), the valve opens to bypass some oil back to the sump. This prevents excessive pressure from damaging seals or the oil filter. Oil Filter What it is: A canister containing a paper-like filter material. Function: This is the main cleaning component. As pressurized oil from the pump flows through it, the filter traps fine particles like dirt, carbon, and metal shavings. This is why it's crucial to change the oil filter during an oil change service. A clogged filter can no longer clean the oil effectively. Oil Galleries (or Passages) What it is: A network of small tunnels and passages drilled into the engine block and cylinder head. Function: They are the "arteries" and "veins" of the system, delivering pressurized oil from the filter to all the critical moving parts of the engine. Dipstick What it is: A long, thin metal rod that goes down into the oil sump through a tube. Function: Used for manually checking the oil level. It has markings (e.g., 'MIN' and 'MAX' or 'ADD' and 'FULL') to show if the oil level is correct. Checking the oil regularly is a key part of vehicle maintenance. C. Engine Components to be Lubricated