ALBERTA HEAVY EQUIPMENT
TECHNICIAN FIRST PERIOD AIT EXAM
REVIEW QUESTIONS WITH CORRECT
ANSWERS AND EXPLANATIONS
1. In a 4-stroke cycle diesel engine, at what point does fuel injection typically begin?
A. Exactly at Top Dead Center (TDC) of the compression stroke
B. During the intake stroke to ensure mixing
C. After Top Dead Center (ATDC) of the power stroke
D. Just before Top Dead Center (BTDC) of the compression stroke
Answer: D
Conceptual Explanation: Fuel injection begins before TDC to allow for ignition delay,
ensuring maximum cylinder pressure occurs shortly after TDC.
2. Which type of fire extinguisher is best suited for an electrical fire in a cab control panel?
A. Class A
B. Class C
C. Class B
D. Class D
,Answer: B
Conceptual Explanation: Class C extinguishers are specifically designed for energized
electrical equipment.
3. When measuring a crankshaft journal with a micrometer, what does a difference in
readings at the ends of the journal indicate?
A. Out-of-roundness
B. Taper
C. Bowing
D. Thrust wear
Answer: B
Conceptual Explanation: Taper is a condition where the diameter of a shaft changes from
one end to the other.
4. According to Pascal’s Law, if a force is applied to a confined liquid, how is the pressure
transmitted?
A. It increases with the volume of the container
B. Only in the direction of the force
C. It decreases as it moves away from the source
D. Equally in all directions
Answer: D
, Conceptual Explanation: Pascal’s Law states that pressure exerted anywhere in a
confined incompressible fluid is transmitted equally in all directions throughout the fluid.
5. What is the purpose of the ‘coke’ or carbon build-up on a diesel fuel injector tip?
A. To insulate the tip from combustion heat
B. To seal the nozzle against the head
C. It is a sign of normal operation
D. It is a detrimental condition that disrupts the spray pattern
Answer: D
Conceptual Explanation: Carbon build-up (coking) on injector tips disrupts the
atomization and spray pattern, leading to poor combustion.
6. Which tool is used to measure the side clearance of a piston ring in its groove?
A. Micrometer
B. Telescoping gauge
C. Dial indicator
D. Feeler gauge
Answer: D
Conceptual Explanation: A feeler gauge is used to measure the small gap between the side
of the piston ring and the ring land.
TECHNICIAN FIRST PERIOD AIT EXAM
REVIEW QUESTIONS WITH CORRECT
ANSWERS AND EXPLANATIONS
1. In a 4-stroke cycle diesel engine, at what point does fuel injection typically begin?
A. Exactly at Top Dead Center (TDC) of the compression stroke
B. During the intake stroke to ensure mixing
C. After Top Dead Center (ATDC) of the power stroke
D. Just before Top Dead Center (BTDC) of the compression stroke
Answer: D
Conceptual Explanation: Fuel injection begins before TDC to allow for ignition delay,
ensuring maximum cylinder pressure occurs shortly after TDC.
2. Which type of fire extinguisher is best suited for an electrical fire in a cab control panel?
A. Class A
B. Class C
C. Class B
D. Class D
,Answer: B
Conceptual Explanation: Class C extinguishers are specifically designed for energized
electrical equipment.
3. When measuring a crankshaft journal with a micrometer, what does a difference in
readings at the ends of the journal indicate?
A. Out-of-roundness
B. Taper
C. Bowing
D. Thrust wear
Answer: B
Conceptual Explanation: Taper is a condition where the diameter of a shaft changes from
one end to the other.
4. According to Pascal’s Law, if a force is applied to a confined liquid, how is the pressure
transmitted?
A. It increases with the volume of the container
B. Only in the direction of the force
C. It decreases as it moves away from the source
D. Equally in all directions
Answer: D
, Conceptual Explanation: Pascal’s Law states that pressure exerted anywhere in a
confined incompressible fluid is transmitted equally in all directions throughout the fluid.
5. What is the purpose of the ‘coke’ or carbon build-up on a diesel fuel injector tip?
A. To insulate the tip from combustion heat
B. To seal the nozzle against the head
C. It is a sign of normal operation
D. It is a detrimental condition that disrupts the spray pattern
Answer: D
Conceptual Explanation: Carbon build-up (coking) on injector tips disrupts the
atomization and spray pattern, leading to poor combustion.
6. Which tool is used to measure the side clearance of a piston ring in its groove?
A. Micrometer
B. Telescoping gauge
C. Dial indicator
D. Feeler gauge
Answer: D
Conceptual Explanation: A feeler gauge is used to measure the small gap between the side
of the piston ring and the ring land.
