Question 2: What is the purpose of a torque wrench in mechanical applications?

Answer: A torque wrench is used to apply a specific amount of torque (rotational force) to a fastener such as a nut or bolt. This ensures that fasteners are tightened to the manufacturer's specifications, preventing damage from over-tightening or failure from under-tightening.

Handle
Dial Indicator
Socket
TORQUE WRENCH

Apply Force Here
Rotational Force Applied Here

Question 3: Explain the difference between SAE and Metric fasteners.

Answer:

• SAE (Society of Automotive Engineers) fasteners use imperial measurements (inches) and are commonly used in the United States.
• Metric fasteners use the metric system (millimeters) and are standard in most countries worldwide.

The key differences include:

• Sizing convention (inches vs. millimeters)
• Thread pitch measurement (threads per inch vs. distance between threads)
• Wrench sizes required for installation/removal
• Head markings for identification

Question 4: In a hydraulic system, what happens when air enters the system?

Answer: When air enters a hydraulic system (a condition known as aeration), several problems occur:

• Spongy or erratic operation due to air's compressibility (unlike hydraulic fluid)
• Increased noise ("knocking" sounds)
• Reduced system efficiency and power
• Potential overheating due to decreased heat dissipation
• Accelerated component wear and possible damage to pumps
• Potential hydraulic lock and system failure

Pressure Fluctuations

HYDRAULIC SYSTEM WITH AIR CONTAMINATION

Question 5: Identify the parts of this basic four-stroke engine.

Answer: The main components of a four-stroke engine are:

1. Cylinder
2. Piston
3. Connecting rod
4. Crankshaft
5. Intake valve
6. Exhaust valve
7. Spark plug
8. Camshaft
9. Timing chain/belt
10. Cylinder head

FOUR-STROKE ENGINE COMPONENTS

Question 6: Calculate the mechanical advantage of this pulley system.

Answer: For this compound pulley system with 2 fixed pulleys and 2 movable pulleys, the mechanical advantage is 4:1. This means that a 100 lb load could be lifted with only 25 lbs of force.

Formula: MA = Number of rope segments supporting the movable pulley(s)

Input Force: 25 lbs

Question 7: What type of bearing is shown in the image, and what are its applications?

Answer: The image shows a tapered roller bearing. This type of bearing can handle both radial loads (perpendicular to the shaft) and thrust loads (parallel to the shaft) simultaneously.

Common applications include:

• Automotive wheel hubs
• Gearboxes
• Machine tool spindles
• Conveyor systems
• Any application requiring support for combined loading

Radial Load
Thrust Load

Question 8: Interpret this wiring diagram and explain the circuit operation.

Answer: This is a starting circuit for a small engine with these components:

• Battery (12V power source)
• Ignition switch (controls power to the system)
• Solenoid/relay (amplifies the control signal to energize the starter)
• Starter motor (converts electrical energy to mechanical rotation)
• Ground connections

When the ignition switch is turned to "START," current flows from the battery through the switch to the solenoid coil. The energized solenoid closes its internal contacts, connecting the battery directly to the starter motor with a heavy-duty circuit capable of handling the high current draw.

Ground
Ground