Answer 10 free questions
No signup, no card — with a written explanation on every answer.
EVT Fire Apparatus: 10 free questions
Tap an answer to see if you're right and why, or switch to Timed and get scored at the end. Each answer is also under its question.
-
EVT DO1 Driver/Operator Inspection
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?
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.
-
EVT F1 Maintenance, Inspection & Testing
During the NFPA 1911 (now NFPA 1910) annual pump service test, at what net pump pressure must a fire pump deliver 100% of its rated capacity?
Show answer
Answer: B. 150 psi
The service test mirrors the original certification points: 100% of rated capacity at 150 psi net pump pressure, 70% at 200 psi, and 50% at 250 psi. 165 psi is the overload test pressure, not the rated-capacity point.
- A: too low; the 100% capacity point is 150 psi
- C: that is the overload test pressure, not rated-capacity
- D: that is the 70% capacity point, not 100%
-
EVT F2 Design & Performance Standards
Per NFPA 1901 (now NFPA 1900), what is the minimum rated fire pump capacity required for an apparatus to be classified as a pumper?
Show answer
Answer: B. 750 gpm (3000 L/min)
NFPA 1901 defines a pumper as a fire apparatus with a permanently mounted fire pump of at least 750 gpm (3000 L/min), a water tank, and a hose body. 500 gpm is below the pumper threshold, and 1000/1250 gpm are common but not the minimum.
- A: 500 gpm is below the 750 gpm pumper threshold
- C: 1000 gpm is a common rating but exceeds the minimum
- D: 1250 gpm is a common rating but above the minimum
-
EVT F3 Fire Pumps & Accessories
In a centrifugal fire pump operating at a constant engine (impeller) speed, as the volume of water being discharged increases, the discharge pressure will:
Show answer
Answer: A. Decrease
A centrifugal pump has an inverse pressure-volume relationship: pressure is highest at churn (no flow) and falls off as flow increases. Unlike a positive-displacement pump it traps no fixed volume, so pressure cannot stay constant or rise with flow.
- B: Centrifugal pressure falls as flow rises; it never increases with flow.
- C: Not positive-displacement; pressure varies with flow, cannot stay constant.
- D: Pressure continuously declines with more flow; it does not stabilize higher.
-
EVT F4 Fire Apparatus Electrical Systems
A fire apparatus alternator generates alternating current in its stator windings. Which internal component converts that AC into the direct current required to charge the batteries and supply the vehicle's DC loads?
Show answer
Answer: B. The diode rectifier bridge
The three-phase AC produced in the stator is converted to DC by the rectifier bridge (typically six diodes). The voltage regulator only controls field current to set output level, and the slip rings/brushes merely feed the rotating field.
- A: Regulator only controls field current to set output; it doesn't rectify AC.
- C: Rotor winding creates the rotating magnetic field; it doesn't convert AC.
- D: Slip rings/brushes only feed field current to rotor; no rectification.
-
EVT F5 Aerial Fire Apparatus
What is the primary function of the stabilizer (outrigger) interlock system on an aerial fire apparatus?
Show answer
Answer: A. Prevent the aerial device from being raised, rotated, or extended until the stabilizers are properly deployed
NFPA 1901 (now NFPA 1900) requires an interlock that keeps the aerial device from operating until the stabilizers/outriggers are set, protecting against tip-over on an unstable base. Pressure limiting is the job of a relief valve, and automatic turntable leveling is a separate (and uncommon) feature, not the interlock's purpose.
- B: Automatic turntable leveling is a separate function from the stabilizer interlock.
- C: Pressure limiting is the relief valve's job, not an interlock's.
- D: The interlock gates aerial motion on stabilizer deployment; it does not cut hydraulic power.
-
EVT F6 Allison Automatic Transmissions
In an Allison electronically controlled automatic transmission, what is the primary purpose of the torque converter lockup clutch (TCC)?
Show answer
Answer: A. Provide a direct mechanical connection between the engine and transmission input, eliminating converter slip
The lockup clutch mechanically couples the converter pump and turbine for a 1:1 drive with no slip, improving efficiency and reducing heat. Torque multiplication is done by the converter and stator when the clutch is released, so that is not the lockup clutch's job.
- B: Multiplication happens in the converter and stator with the lockup clutch released.
- C: Cooler circulation is the charging pump's function, not the lockup clutch's.
- D: The output retarder is a separate hydrodynamic device the TCM commands on its own.
-
EVT F7 Foam Systems
Class A foam concentrate is formulated primarily for fires involving which type of fuel?
Show answer
Answer: A. Ordinary combustibles such as wood, paper, and brush
Class A foam acts as a wetting agent that lowers water's surface tension so it penetrates ordinary combustibles like wood and brush. Flammable-liquid and polar-solvent fires require Class B foam.
- B: Gasoline and diesel are hydrocarbon liquids, which need Class B foam.
- C: Alcohols and ketones need alcohol-resistant Class B foam.
- D: Water-based foam is not applied to energized equipment at all.
-
EVT F8 Hydraulic Systems
According to Pascal's law, pressure applied to a confined hydraulic fluid is:
Show answer
Answer: A. Transmitted equally in all directions
Pascal's law states that pressure on a confined fluid is transmitted undiminished and equally in every direction against all boundaries of its container.
- B: Pressure in a confined fluid is equal throughout, not concentrated at the outlet.
- C: In a static confined fluid, pressure is not lost to travel distance.
- D: Pressure acts on all container surfaces, not just along the flow path.
-
EVT FA4 Advanced Electrical Systems
With the ignition key off, a technician measures resistance across the J1939 CAN-High and CAN-Low backbone conductors. A properly terminated bus should read approximately:
Show answer
Answer: A. 60 ohms
A J1939 backbone is terminated by a 120-ohm resistor at each end, and the two in parallel measure about 60 ohms across CAN-H and CAN-L. A reading near 120 ohms suggests one terminator is missing or open.
- B: 120 ohms indicates only one terminator is present, the other open.
- C: 0 ohms indicates a short between the two conductors.
- D: An open reading indicates a broken backbone or both terminators missing.
Like these?
Overhaul Prep has 19,209 questions across 90 certification tests, every one explained like these — with timed exams and a readiness score.
Start your 24-hour free trial →Studying for EVT? Take a free test for your exact EVT exam →