Lesson Notes By Weeks and Term v3 - Senior Secondary 3
steering systems and its parts
Download the Lessonotes Mobile Nigeria 2025 app for faster lesson access on Android and iPhone.
steering systems and its parts
Download the Lessonotes Mobile Nigeria 2025 app for faster lesson access on Android and iPhone.
Subject: Autopart Merchandizing
Class: Senior Secondary 3
Term: 3rd Term
Week: 1
Theme: Automobile Parts
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
Identify the two types of steering e.g. manual and power as sisted steering. List and identify the parts of steering system. State functions of the parts of steering system.
Honda Accord, various SUVs, and newer commercial vehicles. Most vehicles imported into Nigeria today come with some form of power steering. 2.
3. Parts of the Steering System and Their Functions The components can vary slightly between manual and power steering systems, and between rack-and-pinion and recirculating ball steering gears.
1. Steering Wheel: Function: This is the primary input device for the driver. It provides a grip for the driver to turn the vehicle.
2. Steering Column: Function: Connects the steering wheel to the steering gearbox. It often incorporates universal joints (U-joints) to allow for angle changes and a collapsible design for safety during a collision.
3. Steering Shaft: Function: The internal shaft within the steering column that transmits the rotational input from the steering wheel to the steering gearbox.
4. Steering Gearbox (Steering Gear): Function: Converts the rotational motion of the steering shaft into linear motion (or an arc of motion) needed to turn the wheels.
There are two main types: Rack and Pinion Gear: (Common in smaller cars, modern vehicles) A pinion gear (on the end of the steering column) meshes with a horizontal toothed bar called the rack. As the pinion turns, it moves the rack left or right, which is connected directly to the tie rods.
Recirculating Ball Gear: (Common in larger vehicles, trucks, older cars) Uses a worm gear and a sector gear (Pitman shaft) with recirculating steel balls acting as bearings. The worm gear moves a nut, which in turn moves the sector gear.
5. Pitman Arm (Specific to Recirculating Ball Steering): Function: Attached to the output shaft of the recirculating ball gearbox. It converts the rotary motion of the sector shaft into a back-and-forth arc, which is then transmitted to the rest of the steering linkage.
6. Idler Arm (Specific to Recirculating Ball Steering): Function: Supports the end of the center link/relay rod on the passenger side, mirroring the action of the Pitman arm to maintain proper steering geometry.
7. Center Link / Relay Rod (Specific to Recirculating Ball Steering): Function: A long bar that connects the Pitman arm, idler arm, and the inner tie rods, distributing the steering force to both front wheels.
8. Tie Rods (Inner and Outer): Function: Connect the steering gear (or center link in recirculating ball systems) to the steering knuckles. The outer tie rod end, typically adjustable, allows for wheel alignment adjustments (toe-in/toe-out).
9. Steering Knuckles (Spindles): Function: These are sturdy components to which the wheel hub and brake assembly are attached. The outer tie rod ends connect to the steering knuckles, allowing them to pivot and turn the wheels.
1
0. Power Steering Pump (Hydraulic Power Steering only): Function: Driven by the engine via a belt, it generates hydraulic pressure by circulating power steering fluid.
1
1. Power Steering Fluid Reservoir (Hydraulic Power Steering only): Function: Stores the power steering fluid, allowing for expansion and contraction as well as providing a fill point.
1
2. Power Steering Hoses (Hydraulic Power Steering only): Function: Carry the high-pressure and low-pressure hydraulic fluid between the pump, reservoir, and steering gearbox. 2.
1. Introduction to Steering Systems A steering system is a crucial mechanism in a vehicle that allows the driver to control the direction of travel. Its primary function is to direct the front wheels (and sometimes rear wheels in advanced systems) to steer the vehicle left or right, enabling navigation and control. A well-functioning steering system is essential for vehicle safety, stability, and driver comfort, especially on varied terrains like those found across Nigeria. 2.
2. Types of Steering Systems There are primarily two types of steering systems found in most vehicles: 2.2.
1. Manual Steering System Explanation: In a manual steering system, the driver provides all the effort to turn the wheels through mechanical linkages. There is no hydraulic or electric assistance. The system relies on mechanical advantage achieved through gear ratios within the steering gearbox.
How it Works: The steering wheel is connected to a steering column, which in turn connects to a steering gearbox. The gearbox converts the rotational motion of the steering wheel into linear motion, which is then transmitted to the wheels via a series of rods and linkages (e.g., tie rods). The mechanical advantage provided by the gearing helps the driver turn the wheels, but significant effort is still required, especially at low speeds or when parking. Characteristics and Application in Nigeria: Advantages: Simpler design, fewer components, generally lower maintenance costs, durable.
Disadvantages: Requires considerable driver effort, especially in larger vehicles (e.g., older commercial buses like "Molue" or "Danfo" still in use) or during low-speed maneuvers and parking. Can lead to driver fatigue on long journeys.
Common in Nigeria: Found predominantly in older model vehicles, small, lightweight cars, and some older commercial vehicles or agricultural machinery. For example, older Peugeot 504/505 models, some vintage Volkswagen Beetles, and certain commercial vans might still use manual steering. 2.2.
2. Power-Assisted Steering (Power Steering)
System Explanation: Power steering systems utilize an auxiliary power source (either hydraulic fluid pressure or an electric motor) to reduce the effort required by the driver to turn the steering wheel. This makes steering much easier, especially at low speeds and during parking.
Types of Power Steering: Hydraulic Power Steering (HPS): This is the most common type. It uses hydraulic fluid pressurized by a pump driven by the engine (via a belt). The fluid assists the driver in turning the steering gear.
Components: Power steering pump, fluid reservoir, high-pressure and low-pressure hoses, power steering gearbox (or rack and pinion unit with integrated power cylinder).
How it Works: When the steering wheel is turned, a valve within the steering gear directs hydraulic fluid to one side of a piston or rotary vane, creating pressure that assists in moving the steering linkage and turning the wheels.
Electric Power Steering (EPS): This system uses an electric motor to provide assistance. It is more fuel-efficient as it does not rely on a constantly running engine-driven pump.
Components: Electric motor, control unit (ECU), torque sensor.
How it Works: A torque sensor detects the driver's steering effort, and the ECU signals an electric motor to apply assistance directly to the steering column or steering gear. Characteristics and Application in Nigeria: Advantages: Significantly reduces driver effort, improves maneuverability, enhances driver comfort, better steering response, especially beneficial in heavy traffic conditions prevalent in cities like Lagos or Abuja.
Disadvantages: More complex, higher initial cost, potential for fluid leaks (HPS), may consume some engine power (HPS), more expensive to repair if components fail.
Common in Nigeria: Widely adopted in modern vehicles, including popular models like Toyota Camry, Honda Accord, various SUVs, and newer commercial vehicles. Most vehicles imported into Nigeria today come with some form of power steering. 2.
3. Parts of the Steering System and Their Functions The components can vary slightly between manual and power steering systems, and between rack-and-pinion and recirculating ball steering gears.
1. Steering Wheel: Function: This is the primary input device for the driver. It provides a grip for the driver to turn the vehicle.
2. Steering Column: Function: Connects the steering wheel to the steering gearbox. It often incorporates universal joints 3.
1. Teacher Activities Introduction (10 minutes): Begin by asking students about their experiences with steering vehicles (e.g., bicycles, cars, buses). Initiate a KWL (Know, Want to Know, Learned) chart on the board or chart paper for "Vehicle Steering Systems." Display pictures or diagrams of different steering wheels and car fronts.
Pose questions: "How does a driver change the direction of a vehicle?" "What would happen if the steering system failed on a busy Nigerian road?" Explanation of Steering Types (20 minutes): Present detailed explanations of manual and power-assisted steering systems using visual aids (diagrams, short videos if available). Compare and contrast their mechanisms, advantages, and disadvantages, relating them to common vehicles seen in Nigeria (e.g., comparing the effort to steer an old Peugeot 504 vs. a modern Toyota Corolla). Highlight the two main types of power steering (hydraulic and electric) and their basic principles. Identification of Steering Parts (30 minutes): Use a large, clear diagram of a complete steering system (preferably both rack and pinion and recirculating ball if time permits) projected or drawn on the board. Point to each part and clearly state its name and function. If possible, bring in actual steering system components (e.g., a steering wheel, a tie rod end, a power steering pump) sourced from a local mechanic workshop or junkyard for a hands-on demonstration. This is highly effective in the Nigerian context. Engage students by asking them to identify parts as they are pointed out.
Interactive Group Discussion (15 minutes): Divide students into small groups. Assign each group a task, e.g., "List the parts unique to a hydraulic power steering system" or "Describe how a rack and pinion system works." Facilitate a short feedback session where groups share their findings.
Summarization and Q&A (10 minutes): Review the key concepts: types of steering, main parts, and their functions. Address any questions or misconceptions from students. Conclude by emphasizing the importance of a properly functioning steering system for road safety in Nigeria. 3.
2. Student Activities Brainstorming: Students contribute to the "K" (Know) and "W" (Want to Know) sections of the KWL chart at the beginning of the lesson.
Observation and Listening: Students carefully observe diagrams/physical components and listen to the teacher's explanations.
Note-taking: Students take comprehensive notes on the types of steering, their mechanisms, and the names and functions of each part.
Diagram Labeling (Individual/Pair): Students work individually or in pairs to label blank diagrams of a steering system provided by the teacher, after the explanation.
Group Discussion: Students engage in assigned group tasks, discussing and compiling answers related to specific aspects of steering systems.
Questioning: Students ask clarifying questions during the Q&A session.
Question 1: A driver of an old "Danfo" bus complains of extreme difficulty turning the steering wheel, especially when trying to park or navigate through traffic in Oshodi. This difficulty reduces significantly once the bus is moving at a higher speed. a) Based on this description, what type of steering system is most likely installed in the "Danfo" bus? b) Briefly explain why the steering effort is high at low speeds.
Solution 1: a)
Type of Steering System: Manual steering system. b)
Explanation: In a manual steering system, there is no hydraulic or electric assistance. The driver relies entirely on mechanical advantage provided by the steering gearbox's gear ratio. At low speeds, less centrifugal force acts on the wheels, and the static friction between the tires and the road is higher, requiring greater physical effort from the driver to overcome this resistance and turn the wheels. As speed increases, the turning resistance decreases, making steering slightly easier, though still requiring more effort than a power-assisted system.
Question 2: Identify and state the function of the following parts of a steering system: a) Steering Wheel b) Tie Rods c)
Power Steering Pump Solution 2: a)
Steering Wheel: Function: Provides the primary interface for the driver to input steering commands, allowing them to turn the vehicle. b)
Tie Rods (Inner and Outer): Function: Connect the steering gear (or center link) to the steering knuckles, transmitting the steering force to pivot the wheels left or right. The outer tie rod end also allows for adjustments during wheel alignment. c)
Power Steering Pump: Function: (In hydraulic power steering systems) It generates hydraulic pressure by circulating power steering fluid, which then assists the driver in turning the steering wheel with less effort.
Question 3: A mechanic in Port Harcourt is troubleshooting a steering problem on a client's SUV. He identifies a component that converts the rotational motion from the steering column into linear motion to move the tie rods. He also notes it uses a system of a pinion gear meshing with a toothed bar. a) Name the specific steering gear mechanism described. b) List two other essential parts that connect directly to this mechanism to transmit motion to the wheels.
Solution 3: a)
Specific Steering Gear Mechanism: Rack and Pinion steering gear. b)
Two other essential parts: Inner Tie Rods (or simply Tie Rods) Steering Column (which houses the steering shaft connecting to the pinion)
Auto Mechanic and Repair Shops: Students, through this knowledge, can better understand common steering system failures (e.g., power steering fluid leaks, stiff steering, excessive play, knocking sounds) and their causes. This is invaluable for future mechanics in Nigeria who diagnose and repair vehicles, ensuring roadworthiness and safety, especially with the prevalence of potholes and challenging road conditions. For example, identifying worn tie rod ends as a cause of loose steering.
Spare Parts Merchandising: For students aspiring to work in autopart stores (e.g., Ladipo market in Lagos, Headbridge market in Onitsha), understanding steering components is critical. They must be able to identify specific parts (e.g., a rack and pinion unit for a Toyota Camry vs. a recirculating ball gearbox for a Ford Transit bus), differentiate between manual and power steering parts, and advise customers correctly on compatible replacements for various vehicle makes and models common in Nigeria. This directly impacts sales accuracy and customer satisfaction.
Vehicle Inspection and Road Safety: Knowledge of steering systems is fundamental for anyone involved in vehicle inspection or promoting road safety. Students can appreciate how a faulty steering system (e.g., worn ball joints, damaged power steering pump) poses a significant risk on Nigerian roads, leading to loss of control and accidents. This awareness fosters responsible vehicle maintenance practices among future drivers and vehicle owners.
Commercial Transportation Industry: For those working with commercial transport companies (e.g., bus lines, haulage firms), understanding the differences between manual and power steering affects driver fatigue, operational efficiency, and maintenance budgeting. Fleet managers need to consider the type of steering for their vehicles, especially for long-distance travel across Nigeria, where driver comfort and reduced effort translate to safer and more efficient operations.