Certificate of Qualification Heavy Duty
Equipment Technician (421A) Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a preventive maintenance
program?
A. Increase repair costs
B. Reduce equipment lifespan
C. Detect issues before failure
D. Eliminate inspections
Answer: C
Preventive maintenance helps identify and correct problems
before major failures occur.
2. Which fluid is primarily responsible for heat removal in an engine?
A. Engine oil
B. Coolant
C. Fuel
D. Hydraulic fluid
Answer: B
Coolant circulates through the engine to absorb and remove heat.
3. Excessive black exhaust smoke usually indicates:
A. Lean fuel mixture
B. Coolant leak
C. Over-fueling or restricted air
, D. Low compression
Answer: C
Black smoke forms when fuel is not fully burned due to excess fuel
or lack of air.
4. What component regulates system pressure in a hydraulic circuit?
A. Pump
B. Cylinder
C. Control valve
D. Relief valve
Answer: D
Relief valves protect hydraulic systems from overpressure.
5. Which tool is best for measuring internal cylinder bore wear?
A. Feeler gauge
B. Vernier caliper
C. Dial bore gauge
D. Micrometer ruler
Answer: C
Dial bore gauges measure internal diameter accurately.
6. What is cavitation in a hydraulic system?
A. Excessive pressure
B. Air leaks at fittings
C. Formation and collapse of vapor bubbles
D. Contaminated oil
Answer: C
Cavitation damages components when vapor bubbles collapse
under pressure.
, 7. Diesel engines rely on which principle for ignition?
A. Spark ignition
B. Compression ignition
C. Glow plug ignition only
D. Magnetic ignition
Answer: B
Diesel fuel ignites due to high temperature from compression.
8. A cracked fan belt most commonly causes:
A. Engine knock
B. Overheating
C. Fuel starvation
D. Loss of compression
Answer: B
The belt drives the cooling fan and water pump.
9. Which type of bearing supports radial loads only?
A. Thrust bearing
B. Tapered roller bearing
C. Needle bearing
D. Plain journal bearing
Answer: D
Journal bearings primarily handle radial loads.
10. What is the main function of a turbocharger?
A. Reduce exhaust noise
B. Increase engine compression ratio
C. Force more air into cylinders
D. Cool intake air
Equipment Technician (421A) Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of a preventive maintenance
program?
A. Increase repair costs
B. Reduce equipment lifespan
C. Detect issues before failure
D. Eliminate inspections
Answer: C
Preventive maintenance helps identify and correct problems
before major failures occur.
2. Which fluid is primarily responsible for heat removal in an engine?
A. Engine oil
B. Coolant
C. Fuel
D. Hydraulic fluid
Answer: B
Coolant circulates through the engine to absorb and remove heat.
3. Excessive black exhaust smoke usually indicates:
A. Lean fuel mixture
B. Coolant leak
C. Over-fueling or restricted air
, D. Low compression
Answer: C
Black smoke forms when fuel is not fully burned due to excess fuel
or lack of air.
4. What component regulates system pressure in a hydraulic circuit?
A. Pump
B. Cylinder
C. Control valve
D. Relief valve
Answer: D
Relief valves protect hydraulic systems from overpressure.
5. Which tool is best for measuring internal cylinder bore wear?
A. Feeler gauge
B. Vernier caliper
C. Dial bore gauge
D. Micrometer ruler
Answer: C
Dial bore gauges measure internal diameter accurately.
6. What is cavitation in a hydraulic system?
A. Excessive pressure
B. Air leaks at fittings
C. Formation and collapse of vapor bubbles
D. Contaminated oil
Answer: C
Cavitation damages components when vapor bubbles collapse
under pressure.
, 7. Diesel engines rely on which principle for ignition?
A. Spark ignition
B. Compression ignition
C. Glow plug ignition only
D. Magnetic ignition
Answer: B
Diesel fuel ignites due to high temperature from compression.
8. A cracked fan belt most commonly causes:
A. Engine knock
B. Overheating
C. Fuel starvation
D. Loss of compression
Answer: B
The belt drives the cooling fan and water pump.
9. Which type of bearing supports radial loads only?
A. Thrust bearing
B. Tapered roller bearing
C. Needle bearing
D. Plain journal bearing
Answer: D
Journal bearings primarily handle radial loads.
10. What is the main function of a turbocharger?
A. Reduce exhaust noise
B. Increase engine compression ratio
C. Force more air into cylinders
D. Cool intake air
