MOTOR MECHANICS (Y11)

Purpose of Housekeeping in a Workplace

Housekeeping in a mechanic workshop is essential for safety, productivity, equipment longevity, and customer trust. 

A clean, organized environment reduces hazards like slips and falls, enables faster work by keeping tools accessible, prevents premature wear and tear on machinery, and presents a professional image that builds customer confidence. 

More on PPEs  - Reading Purpose Only

Protective Clothing

Protective clothing includes shirts, pants, shoes and gloves. These items are the first line of defense against injuries and accidents and must be worn when performing any work. 

Work Clothing

Always wear appropriate work clothing. Whether this is a one-piece coverall/overall or a separate shirt and pants, the clothes you work in should be comfortable enough to allow you to move, without being loose enough to catch on machinery. 

Footwear

The proper footwear or safety boot provides protection against items falling on your feet, chemicals, cuts, abrasions, and slips. The soles of your shoes must be acid and slip resistant, and the upper must be made from a puncture-proof material such as leather. 

Hand protection

 Hands are a very complex and sensitive part of the body with many nerves, tendons, and blood vessels. They are susceptible to injure and damage. Nearly every activity performed on a vehicle requires the use of your hands, which provides many opportunities for injury. Whenever possible, wear gloves to protect your hands.

Chemical Gloves                                                                                                                                                                                           

They should also be when working on batteries. Heavy-duty and impenetrable chemical gloves should always be worn when using solvents and cleaners. Always inspect chemical gloves for holes or cracks before using them, and replace them when they become worn.

Leather Gloves

Leather gloves will protect your hands from burns when welding or handling hot components.

Light-Duty Gloves

Light-duty gloves should be used to protect your hands from exposure to grease and oils. 

Ear protection

Ear protection should be worn when sound levels reach B5 dB (decibel) and above, when you are working around operating machinery for a continual period of time, or when the equipment you are using produces loud noise. 

Disposable Dust Mask

A disposable dust mask is made from paper with a wire-reinforced edge that is held to your face with an elastic strip. It covers your mouth and nose and is disposed of at the completion of the task. 

Respirator

The respirator has removable cartridges that can be changed according to the type of contaminant being filtered.

Eye Protection

Eyes are very sensitive organs and they need to be protected against injuries. There are many things in the workshop environment that can damage or injure eyes, such as high-velocity particles coming from a grinder or high-intensity light coming from a welder. 

Safety Glasses

Safety glasses have built-in side shields to help protect your eyes from the side.

Their main purpose is to protect your eyes from direct impact or debris damage.

 Welding Helmet

Always wear a welding helmet when using or assisting a person using welding machines. The light from a welding arc is very bright and contains high levels of ultraviolet radiation. The lens on a welding helmet has heavily tinted glass to reduce the intensity of the light from the welding tip.

Full Face Shield.

It is necessary to use full face shield when using solvents and cleaners, epoxies and resins or when working on a battery. The clear mask of the face shield allows you to see all that you are doing but will protect your entire face from chemical burns should there be any splashes or battery explosions. 

It is also recommended that you use a full face shield combined with safety glasses when working using a bench or angle grinder. 

ACTIVITY 1

1. What is PPE in a workplace? (1mk)

2.  Give 5 examples of PPEs and their functions (10mks)

3. When handling batteries what PPE item to safeguard your hands is best to use? (1mk)

4. When handling solvents, cleaners, epoxies, and resins (chemicals), what PPE item to safeguard your entire face and allows you to see all that you are doing is best to use?

5. What does Housekeeping in the workshop involve? (3mks)

6. Describe 4 ways that you will conduct your housekeeping in the workplace (8mks)

7. If your housekeeping in the workplace is frequently carried out, what impacts will it greatly reduce? (5mks)

8. Summarise the purpose of Housekeeping in a workplace (5mks)

9. Fire extinguisher bottle content is identified by the color of a band around it. Identify the contents of these color bands:-

a. Red ____________________

b. White and Red _______________________

c. Cream _______________________

d. Blue _________________________

e. Yellow ________________________

f. Green _________________________

g. Black ________________________  (7mks)

10. There are 4 steps in using a Fire extinguisher. Briefly describe the actions you will take in each step (12mks)

Tools for Threading

In a mechanics shop, the primary tools for creating and repairing threads are taps for internal (female) threads and dies for external (male) threads. These tools, often used with handles or on machines, include specialized types for hand-tapping, machine-tapping, and for cleaning up damaged threads.  

Abrading Tools and Materials

A mechanics shop uses a wide range of abrading tools and materials for cutting, grinding, shaping, and finishing metal parts. These items are essential for tasks such as removing rust, preparing surfaces for paint, and deburring components. 

The primary types include bonded, coated, and non-woven abrasives, each with specific applications. 

Bonded abrasives consist of abrasive grains held together by a strong bonding agent, forming rigid, solid tools. 

• Grinding wheels: These are thick, solid discs for heavy-duty material removal, cutting, and shaping of hard metals. They are commonly made with aluminum oxide (for steel) or silicon carbide (for cast iron and non-ferrous metals) and are used with bench or angle grinders.

• Cut-off wheels: Thinner and more brittle than grinding wheels, cut-off wheels are designed for slicing and trimming metal components, such as exhaust pipes or body panels.

• Honing stones: Small, abrasive sticks used to finish and polish the interior of cylinder bores, ensuring a proper seal with piston rings. 

Coated abrasives

Coated abrasives feature a flexible backing material, like paper or cloth, with abrasive grains glued to one side. 

• Sandpaper and emery cloth: Available in sheets, discs, and rolls of various grits, these are fundamental for preparing surfaces by removing paint, rust, and imperfections. Emery cloth is specifically designed for use on metal.

• Abrasive belts: Used with belt sanders for quick material removal over large surface areas.

• Flap discs: Combine grinding and finishing functions into a single disc by overlapping multiple coated abrasive flaps. They are used on angle grinders for blending and finishing welds. 

Non-woven and other abrasives

These products are made of synthetic fibers impregnated with abrasive grains, offering a more flexible and gentler abrading action. 

• Abrasive pads (scuff pads): These flexible pads are used by hand for light scuffing, cleaning, and surface preparation on hard-to-reach or contoured surfaces.

• Wire brushes and wheels: Made of steel or nylon wire, these are used with drills, grinders, or by hand for removing rust, paint, and burrs. They clean the surface without removing significant base material.

• Polishing compounds and pads: Applied to surfaces with a buffing pad or cloth, these fine abrasives create a smooth, glossy finish on painted surfaces and bare metal. 

Abrasive materials

The type of abrasive grain determines its hardness and application. Common types include: 

• Aluminum oxide: A tough and durable material suitable for grinding and sanding ferrous metals, including steel.

• Silicon carbide: A very hard and sharp material used for non-ferrous metals, cast iron, and composites.

• Zirconia alumina: Highly durable and self-sharpening, this is effective for heavy-duty grinding and removing stock on metals.

• Ceramic alumina: Extremely tough and self-sharpening, ideal for working with hard metals like stainless steel.

• Diamond: The hardest abrasive, used in specialized wheels for cutting and grinding very hard materials, such as carbide, glass, and ceramic. 

Tools for Pulling and Pushing

Pulling tools in a mechanics shop, also called pullers, are specialized tools designed to remove components that are pressed or stuck in place, such as gears, pulleys, wheel hubs, and seals. Common examples include 3-jaw pullers and 2-jaw pullers,  

Types of Pulling Tools

• 3-Jaw Pullers:
  These versatile tools are a staple in any garage, featuring three gripping arms that can be configured for internal or external gripping. They are ideal for removing a wide variety of components, including gears, pulleys, and wheel hubs. 

• 2-Jaw Pullers:
  Similar to 3-jaw pullers, but with only two arms, they are used for components where a 3-jaw design may not fit. 

• Tie Rod Pullers:
  These specialized tools are designed specifically to remove tie rod ends from a vehicle's steering system. 

• Oil Filter Wrenches:
  Used to grip and turn oil filters to remove them from the engine block. 

• Pry Bars:
  These are basic but essential tools that can be used to lever stubborn parts into place or separate them. 

• Seal Pullers:
  These tools are designed to safely extract various types of seals without damaging the surrounding components. 

• Punches and Chisels:
  Can be used in conjunction with a hammer to help persuade parts loose, but care must be taken to avoid damage. 

ACTIVITY 2

ENGINES

1. TWO-STROKE ENGINE

A two-stroke engine is a type of internal combustion engine that completes a power cycle with two strokes of the piston - 

• one up and one down, in one revolution of the crankshaft. 

How It Works

• 1. First Stroke (Upstroke):

• As the piston moves up, it compresses the fuel-air mixture already in the cylinder. Simultaneously, a vacuum is created in the crankcase, drawing a fresh mixture of air, fuel, and oil into the crankcase through the intake port. 

• 2. Second Stroke (Downstroke):

• The spark plug ignites the compressed mixture, pushing the piston down (the power stroke). As the piston moves down, it uncovers the exhaust port, allowing exhaust gases to escape, and then uncovers the transfer port. The fresh, pressurized air-fuel-oil mixture from the crankcase then rushes into the cylinder, pushing out the remaining exhaust gases and filling the cylinder for the next compression stroke. 

2. FOUR-STROKE ENGINE