Free EVT DO1 practice test: Driver/Operator Inspection

Free EVT DO1 practice test: 10 questions

Questions from our DO1 bank, written to EVTCC's learning objectives and the 2024 NFPA 1900 and 1910. Tap an answer to see if you're right and why, or switch to Timed for the real test's pace. Every answer is below each question.

1. On a properly functioning air-brake system, at what approximate pressure does the governor cut OUT and stop the compressor from loading more air into the tanks?

   AAbout 60 psi BAbout 90 psi CAbout 125 psi DAbout 150 psi
   Show answer

   Answer: C. About 125 psi

   The governor typically cuts out (unloads the compressor) at about 125 psi and cuts back in near 100 psi, the figures the CDL manual gives. The exact settings are the vehicle maker's, and the federal in-use standard (49 CFR 570.57) allows a cut-out no higher than 135 psi and a cut-in no lower than 80 psi unless the maker recommends other values. Confirming the settings verifies the system charges to a safe operating pressure.

   • A: That is near the low-air warning point, not cut-out.
   • B: Below normal cut-out; the system keeps building past this.
   • D: Above the normal cut-out range and a sign of a governor fault.

2. After the governor cuts out and the driver makes several brake applications, the compressor should begin loading the tanks again (cut in) at approximately:

   A100 psi B60 psi C40 psi D20 psi
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   Answer: A. 100 psi

   Cut-in normally occurs around 100 psi so the system recharges before pressure falls dangerously low. A cut-in far below this range indicates a governor problem.

   • B: That is the low-air warning region, not cut-in.
   • C: Far below normal cut-in; brakes are near failure.
   • D: Spring brakes are applying by this point.

3. In a dual air-brake system, published standards say air pressure should build from 85 to 100 psi within about:

   A45 seconds B3 minutes C10 seconds D5 minutes
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   Answer: A. 45 seconds

   A healthy dual system builds 85-100 psi in roughly 45 seconds at operating rpm; slow build-up suggests a weak compressor or a leak. This is a standard CDL pre-trip check.

   • B: Far too slow for a dual system in this range.
   • C: Faster than the standard and not the published figure.
   • D: Indicates a serious build-up problem.

4. During the static air-leakage check on a single (straight) apparatus — engine off, fully charged, brakes released — the pressure drop should not exceed:

   A2 psi in one minute B10 psi in one minute C2 psi in ten seconds DNo drop at all is acceptable
   Show answer

   Answer: A. 2 psi in one minute

   For a single vehicle the allowable static leakage is less than about 2 psi per minute (3 psi for combinations). Excess leak-down means a system leak that must be corrected.

   • B: Far exceeds the allowable leak-down rate.
   • C: Much too fast; that would indicate a large leak.
   • D: A small, slow drop within limits is acceptable.

5. Two technicians discuss the applied-leakage test. Technician A says you fully charge the system, shut the engine off, and hold firm foot-brake pressure while watching the gauge. Technician B says for a single vehicle the applied leak-down should be less than about 3 psi in one minute. Who is correct?

   ATechnician A only BTechnician B only CBoth Technicians A and B DNeither Technician
   Show answer

   Answer: C. Both Technicians A and B

   Both are right: the test is performed with a steady full brake application, engine off, and a single vehicle should lose less than roughly 3 psi per minute (4 psi for combinations).

   • A: B is also correct, so 'A only' is wrong.
   • B: A is also correct, so 'B only' is wrong.
   • D: Both statements are correct, so 'neither' is wrong.

6. If air pressure continues to fall, the spring (parking) brakes will apply automatically. On most apparatus this happens somewhere in the range of:

   A20 to 45 psi B60 to 75 psi C90 to 100 psi D0 psi only
   Show answer

   Answer: A. 20 to 45 psi

   Spring brakes typically knock on automatically between about 20 and 45 psi, which is why the low-air warning must alert the driver earlier (around 60 psi). It prevents a fully uncontrolled loss of braking.

   • B: This is above where spring brakes set; the warning is here.
   • C: Normal operating pressure; brakes are not applying.
   • D: They apply before reaching 0 psi.

7. For an accurate engine-oil dipstick reading during the daily check, the apparatus should be:

   AOn level ground with the engine off for a few minutes BRunning at high idle while the dipstick is pulled and read CParked nose-down on a steep grade with the wheels chocked DFully loaded and moving down the road at road speed
   Show answer

   Answer: A. On level ground with the engine off for a few minutes

   Oil should be checked on level ground with the engine off so it has drained back to the pan for a true level. Checking while running or on a grade gives a false reading.

   • B: With the engine running, oil is up in the engine instead of the pan and the reading comes up low.
   • C: Oil pools toward the low end of the pan on a grade, so the dipstick reads a false level.
   • D: A dipstick cannot be read on a moving apparatus, and the oil is circulating while it moves.

8. When the driver/operator shifts from road gear into pump, the 'OK to pump' (pump engaged) indicator confirms that:

   AThe pump has engaged and the drivetrain is configured for pumping BThe booster tank has been drawn completely empty by the pump CThe aerial has been raised and extended to its full reach DThe parking brake has released so the wheels can turn freely
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   Answer: A. The pump has engaged and the drivetrain is configured for pumping

   The OK-to-pump/pump-engaged indicator (often a green light) tells the operator the pump shift is complete and the drivetrain is correctly configured before opening discharges. Pumping without confirming can damage the drivetrain.

   • B: The indicator reports the pump shift, not how much water is left in the tank.
   • C: Aerial position is reported by its own controls, not by the pump-shift light.
   • D: Correct pump operation requires the parking brake set, not released.

9. The minimum legal tread depth for the front (steer) tires of the apparatus is:

   A4/32 inch B2/32 inch C1/32 inch D8/32 inch
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   Answer: A. 4/32 inch

   Steer-axle tires must have at least 4/32 inch of tread; other axles are held to 2/32 inch.

   • B: 2/32 inch is the minimum for non-steer axles, not steer tires.
   • C: 1/32 inch is below any legal minimum.
   • D: 8/32 inch is more than the required minimum.

10. Regarding SCBA and loose equipment inside the cab and body, the driver/operator should ensure that:

    ASCBA and equipment are secured in brackets/mounts so they cannot become projectiles BSCBA cylinders are laid loose on the seat so crews can grab them while rolling CHand tools are stacked unsecured on the dash within easy reach of the crew DNothing needs securing as long as every crew member is belted in
    Show answer

    Answer: A. SCBA and equipment are secured in brackets/mounts so they cannot become projectiles

    Unsecured SCBA and tools become dangerous projectiles in a crash or hard stop, so all equipment must be held in proper brackets or compartments. Securement protects the crew and is verified during readiness checks.

    • B: A loose cylinder on a seat flies forward in a crash no matter how fast it can be grabbed.
    • C: Unsecured tools on the dash become projectiles in a hard stop.
    • D: Seatbelts restrain people, not the equipment that would strike them.