Class: Senior Secondary School 1 (SS1, SS 1, SSS1, SSS 1)
Term: 2nd Term
Week: 3
Age: 15 years
Duration: 45 minutes
Subject: Auto Mechanic Work
Curriculum Theme: Auto Mechanic Work
Previous Lesson: Types of Engine: Cylinder Liners and Construction.
Topic: TRANSMISSION SYSTEM – Layout and Components
Subject Matter: transmission system layout, engine to clutch connection, gearbox function, universal joint, propeller shaft, rear axle, half shafts

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define the transmission system.
Identify and list the main components of a vehicle’s transmission system.
Describe the function of each component of the transmission system.

Affective Domain:

Appreciate the importance of a well-functioning transmission system in a vehicle.
Show interest in learning more about auto mechanic principles.

Psychomotor Domain:

Sketch a simple layout of the transmission system.
Correctly label the components of the transmission system.

Participate actively in class discussions about the transmission system.

Reference Materials

The following resources were used in planning this lesson:

9 Years Basic Education Curriculum for Auto Mechanic Work.
State Unified Scheme of Work for Senior Secondary Schools.
Auto Mechanic Work for Senior Secondary Schools by E.A. Adeleye.

Instructional Materials

The teacher will teach this lesson with the aid of:

Charts showing the transmission system layout.
Models of transmission components (e.g., clutch, gearbox).
Posters illustrating different parts.
A live vehicle (if available) to show the components.

Rationale for the Lesson

This lesson helps pupils understand how power is transferred from the engine to the wheels of a vehicle. Understanding the transmission system is important for diagnosing vehicle problems and performing basic maintenance, which is useful in daily life and for future careers in auto mechanics.

Prerequisite/Previous Knowledge

Pupils should have basic knowledge of vehicle parts and the function of an internal combustion engine.

Lesson Content/Board Summary

TRANSMISSION SYSTEM – Layout and Components

Definition of Transmission System

The transmission system is a group of components in a vehicle that transfers power from the engine to the drive wheels. It allows the driver to control the speed and torque of the vehicle.

Purpose of the Transmission System

The main purpose of the transmission system is to:

Transmit power from the engine to the wheels.
Change the engine’s speed and torque to suit different driving conditions (e.g., starting, accelerating, climbing hills).
Allow the vehicle to move backward (reverse).
Allow the engine to run without moving the vehicle (neutral).

Layout and Components of the Transmission System

The main components of a typical rear-wheel-drive transmission system, in sequential order from the engine, are:

1. Engine to Clutch Connection

The engine’s crankshaft is connected to the flywheel. The clutch assembly is bolted to the flywheel. The clutch connects and disconnects the engine from the gearbox, allowing for smooth gear changes and stopping without stalling the engine.

2. Gearbox (Manual Transmission)

The gearbox, also known as the transmission, contains a series of gears that allow the driver to select different gear ratios. Its function is to:

Increase or decrease the torque and speed transmitted to the wheels.
Provide a reverse gear for moving backward.
Provide a neutral position to disconnect the engine from the drive wheels.

3. Propeller Shaft (Drive Shaft)

The propeller shaft is a long, rotating shaft that transmits power from the gearbox to the rear axle. It is typically found in rear-wheel-drive and four-wheel-drive vehicles.

4. Universal Joints

Universal joints (U-joints) are flexible couplings located at both ends of the propeller shaft. Their function is to:

Allow the propeller shaft to transmit power at varying angles as the suspension moves up and down.
Compensate for changes in the distance between the gearbox and the rear axle.

5. Rear Axle Assembly

The rear axle assembly receives power from the propeller shaft and distributes it to the rear wheels. It consists of:

Differential: A gear system that allows the wheels on the same axle to rotate at different speeds when turning corners.
Axle Housing: Encloses the differential and axle shafts.

6. Half Shafts (Axle Shafts)

Half shafts are short shafts that extend from the differential within the rear axle housing to each drive wheel. They transmit the final power to the wheels.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils and reviews the previous lesson briefly. The teacher then asks pupils what makes a car move and how the engine’s power reaches the wheels, leading into the topic of the transmission system.
Pupils’ Activity: Pupils respond to questions and listen attentively.
Learning Point: Pupils recall previous knowledge and are introduced to the new topic.

Step 2: Definition and Purpose of Transmission System

Time: 7 minutes
Teaching Skill: Explanation/Lecture
Teacher’s Activity: The teacher defines the transmission system and explains its overall purpose in a vehicle, using charts or diagrams to illustrate.
Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification.
Learning Point: Pupils understand the basic concept and importance of the transmission system.

Step 3: Engine to Clutch Connection and Gearbox Function

Time: 7 minutes
Teaching Skill: Explanation/Demonstration
Teacher’s Activity: The teacher explains how the engine connects to the clutch and then to the gearbox. The teacher then describes the function of the clutch and the gearbox, emphasizing how gears allow for speed and torque changes, possibly using a model or diagram.
Pupils’ Activity: Pupils observe the diagrams/models, listen, and note down key functions.
Learning Point: Pupils understand the initial stages of power transfer and the role of the gearbox.

Step 4: Propeller Shaft and Universal Joints

Time: 7 minutes
Teaching Skill: Explanation/Visualisation
Teacher’s Activity: The teacher explains the role of the propeller shaft in transmitting power from the gearbox to the rear axle. The teacher then describes the function of universal joints, highlighting their importance in accommodating movement.
Pupils’ Activity: Pupils listen, observe charts, and conceptualize the movement.
Learning Point: Pupils learn about the intermediate power transmission components.

Step 5: Rear Axle and Half Shafts

Time: 7 minutes
Teaching Skill: Explanation/Illustration
Teacher’s Activity: The teacher explains the components of the rear axle assembly, including the differential and axle housing. The teacher then describes the function of the half shafts in delivering power to the wheels, possibly showing these parts on a live vehicle if available.
Pupils’ Activity: Pupils listen, observe, and ask questions about the final drive components.
Learning Point: Pupils understand how power is finally delivered to the drive wheels.

Step 6: Sketching and Labeling the Layout

Time: 5 minutes
Teaching Skill: Demonstration/Practical Application
Teacher’s Activity: The teacher quickly sketches a simple diagram of the entire transmission system layout on the board, labeling each component as discussed. The teacher encourages pupils to also make a simple sketch.
Pupils’ Activity: Pupils copy the sketch and labels into their notebooks.
Learning Point: Pupils can visually represent the transmission system and its components.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define the term ‘transmission system’.
List any three main components of a vehicle’s transmission system.
State one function of the gearbox.
Why are universal joints important in the transmission system?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 2 minutes
Teaching Skill: Summarization/Consolidation
Teacher’s Activity: The teacher summarizes the key points of the lesson, reiterating the sequential flow of power through the transmission system. The teacher then assigns homework, asking pupils to draw a neat diagram of the transmission system and label its parts.
Pupils’ Activity: Pupils listen to the summary and note down the homework.
Learning Point: Pupils consolidate their understanding of the transmission system.

Lesson Keywords

Transmission System – The components that transfer power from the engine to the drive wheels.
Clutch – Connects and disconnects the engine from the gearbox.
Gearbox – Changes engine speed and torque to suit driving conditions.
Propeller Shaft – Transmits power from the gearbox to the rear axle.
Universal Joint – Allows power transmission at varying angles.
Rear Axle – Receives power from the propeller shaft and distributes it to the wheels.
Half Shafts – Final shafts that transmit power from the differential to the wheels.

Differentiation

The teacher will provide additional support to pupils who are struggling by offering simplified diagrams and one-on-one explanations. Advanced learners will be encouraged to research different types of transmission systems (e.g., automatic transmission, front-wheel drive).

Note for teachers using this lesson plan

Teachers should ensure that diagrams and models are clear and large enough for all pupils to see. Practical demonstration on a live vehicle, if available, greatly enhances understanding. Encourage pupils to ask questions and relate the concepts to everyday driving experiences.