What is the main purpose of maintenance? Briefly explain how basic preventative maintenance should be performed on the following systems: Chain drive systems Belt drive systems State TWO properties of EACH of the following nylon products: Polyethylene (PET) Polypropylene (PP) Polystyrene (PS) State THREE factors that influence the coefficient of friction - NSC Mechanical Technology Fitting and Machining - Question 9 - 2022 - Paper 1

Preventative maintenance for chain drive systems includes:

• Cleaning uncovered drives to avoid debris buildup.
• Checking sprocket teeth and link plate wear to ensure proper engagement.
• Applying lubricants to reduce wear and friction.
• Checking the functioning of tensioning devices to maintain the correct chain tension.
• Inspecting chains regularly for elongation to prevent failure.

Preventative maintenance for belt drive systems involves:

• Checking the wear and tear on the belt to identify any signs of damage.
• Ensuring proper alignment of the belt to prevent slippage and wear.
• Checking the tension setting to guarantee the belt is neither too loose nor too tight.
• Regularly inspecting the tensioning devices for functionality.

1. Stiff: Polyethylene (PET) is rigid and maintains its shape under stress.
2. Strong: It has a high tensile strength, making it resistant to breaking.

1. Good fatigue resistance: Polypropylene can withstand repeated stress without failing.
2. Heat resistance: It can endure high temperatures without deforming.

1. Good insulation properties: Polystyrene is effective as an insulator, minimizing heat transfer.
2. Light weight: It is low in density, making it easy to handle and transport.

1. Surface roughness/texture: The textures of surfaces in contact can increase or decrease friction.
2. Type of lubricant: The effectiveness of lubricant affects the ease of movement between surfaces.
3. Temperature: Temperature changes can alter material properties and frictional forces.

Thermo-hardened composites undergo a chemical change during the moulding process that creates irreversible bonds. Once set, these materials cannot be re-heated to soften because their structure is permanently altered, preventing reshaping.

1. V-belt: A type of belt with a 'V' shaped cross-section, allowing for better friction and grip.
2. Flat belt: A simple, flat belt used in traditional applications for transferring power.
3. Toothed/Timing belt: A belt with teeth that interlock with pulleys, allowing for precise timing and positioning.