Free Red Seal Truck and Transport Mechanic Examination Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Red Seal Truck and Transport Mechanic Examination practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1A mechanic is preparing to jack up the right-front wheel of a truck. Following the CCOHS guidance for using a jack, which wheel should be chocked on both sides?

   1. A.The left-rear wheelCorrect answer: A
   2. B.The right-rear wheel
   3. C.The left-front wheel
   4. D.The right-front wheel

   Explanation: CCOHS says to "Use chocks in front and back of the wheel that are on the diagonal from the wheel that will be raised". The wheel diagonally opposite the right-front wheel is the left-rear wheel.

   Reference: CCOHS: Garages – Working Under Vehicles — What are some safety tips to know when using a jack?

2. 2During inspection of a diesel truck's aftertreatment system, a mechanic identifies the component whose filter medium physically traps exhaust particulate matter. Which component is it?

   1. A.Diesel oxidation catalyst
   2. B.Diesel particulate filterCorrect answer: B
   3. C.Selective catalytic reduction catalyst
   4. D.Lean NOx trap catalyst

   Explanation: The EPA describes a diesel particulate filter as using a "metallic filter, to physically trap PM and remove it from the exhaust stream." The other listed components are catalytic aftertreatment devices rather than the particulate filter.

   Reference: EPA Diesel Technology Verification Application — Appendix: Technology Definitions, 1.b, Diesel Particulate Filter

3. 3During an air-brake inspection, a mechanic checks the component intended to stop air that has left the supply tank from flowing back into it. Which component provides this function?

   1. A.Compressor governor
   2. B.Air dryer
   3. C.One-way check valveCorrect answer: C
   4. D.Pressure safety valve

   Explanation: The Ontario air-brake handbook states: "When air flows out of the supply tank, it is prevented from returning by one-way check valves." The governor regulates compressor loading, the dryer removes moisture, and the safety valve relieves overpressure.

   Reference: Ontario Official Air Brake Handbook: Air Supply Subsystem — One-way check valve

4. 4During a starting-circuit voltage-drop test, a mechanic measures 0.25 V on the positive cable and 0.10 V on the negative cable. What is the combined cable voltage drop?

   1. A.0.15 V
   2. B.0.25 V
   3. C.0.35 VCorrect answer: C
   4. D.0.45 V

   Explanation: The heavy-duty troubleshooting guide instructs technicians to "Add the Positive side and Negative side voltage drops". The combined drop is 0.25 V + 0.10 V = 0.35 V. Subtracting yields 0.15 V; omitting the negative side yields 0.25 V; adding the negative drop twice yields 0.45 V.

   Reference: Heavy Duty Troubleshooting Guide: Starting and Charging System Testing — Perform Starter Main Cables Voltage Drop Test, step 8

5. 5During a clutch inspection, the driven discs bind on worn transmission input-shaft splines and cannot slide freely when the clutch is released. Which clutch condition can this restriction cause?

   1. A.Clutch chatter
   2. B.Clutch slippage
   3. C.Clutch grabbing
   4. D.Clutch dragCorrect answer: D

   Explanation: Eaton explains that spline wear can "prevent the driven discs from sliding freely, causing poor clutch release (clutch drag)." The restriction interferes with disengagement, rather than describing slip or engagement shudder.

   Reference: Eaton Heavy-Duty Clutch Service Manual — SoloAdvantage self-adjusting clutch installation, inspect transmission input shaft

6. 6A mechanic inspects an emergency-locking seat belt in a truck cab. Which component is intended to lock the webbing during a sudden stop?

   1. A.The retractorCorrect answer: A
   2. B.The belt anchor
   3. C.The belt buckle
   4. D.The pretensioner

   Explanation: The vehicle manual explains: "During a collision or sudden stop the retractor locks to restrain your body." The anchor and buckle secure the assembly, while a pretensioner tightens webbing rather than providing the described emergency-locking retractor function.

   Reference: Honda Owner's Manual: Seat Belts — About Your Seat Belts, p. 38

7. 7A mechanic traces refrigerant through a trailer refrigeration unit. In which component does low-pressure refrigerant absorb heat from return air and vaporize?

   1. A.Condenser coil
   2. B.Evaporator coilCorrect answer: B
   3. C.Receiver tank
   4. D.Expansion valve

   Explanation: Carrier describes return-air heat being absorbed by the refrigerant, "causing it to vaporize in the evaporator coil." The condenser rejects heat, the receiver stores liquid refrigerant, and the expansion valve reduces pressure.

   Reference: Carrier Transicold: Refrigeration Unit Description — Refrigeration system operation

8. 8On a truck with a conventional coolant-based cab heater, which component transfers heat from warm engine coolant to the ventilation air?

   1. A.Heater coreCorrect answer: A
   2. B.Charge-air cooler
   3. C.Evaporator core
   4. D.Condenser core

   Explanation: DENSO explains that "The warm engine coolant flows through the heater core and exchange heat with the air in the vehicle interior". The other components exchange heat in the intake or refrigeration circuits.

   Reference: DENSO: How Heater Cores Work — How heater cores work

9. 9A technician checks the theoretical retracting force of a truck's single-rod hydraulic cylinder. The piston area is 4.0 in², the rod area is 1.0 in², and rod-side pressure is 1,800 psi. With the opposite side vented and friction neglected, what is the retracting force?

   1. A.1,800 lbf
   2. B.5,400 lbfCorrect answer: B
   3. C.7,200 lbf
   4. D.9,000 lbf

   Explanation: The NCDOT research report gives the retraction relationship "𝑅 = (𝐴𝑝 − 𝐴𝑟 ) × 𝑃". The effective area is 4.0 − 1.0 = 3.0 in², so force is 3.0 in² × 1,800 lbf/in² = 5,400 lbf. Using only rod area gives 1,800 lbf; using full piston area gives 7,200 lbf; adding the areas gives 9,000 lbf.

   Reference: North Carolina DOT: Research Project 2018-16 Final Report — Section 4.1.4, Hydraulic Circuit, equation 4.2, page 83

10. 10A hybrid truck's high-voltage traction battery supplies its 12-volt accessories and recharges its auxiliary battery. Which component reduces the battery voltage for these loads?

    1. A.Traction motor inverter
    2. B.Onboard charger rectifier
    3. C.DC-to-DC converterCorrect answer: C
    4. D.Regenerative motor generator

    Explanation: The U.S. Department of Energy describes the DC/DC converter: "This device converts higher-voltage DC power from the traction battery pack to the lower-voltage DC power needed to run vehicle accessories and recharge the auxiliary battery." The inverter supplies the traction motor, the onboard charger rectifies external charging power, and the motor generator converts mechanical energy to electricity.

    Reference: Alternative Fuels Data Center: How Do Hybrid Electric Cars Work? — Key Components of a Hybrid Electric Car, DC/DC converter