Answer 10 free questions

Detroit Diesel: 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.

1. Detroit Diesel DD13 / DD15 Heavy-Duty

   Where is the timing gear train located on the Detroit DD platform (DD13/DD15)?

   AAt the front, behind the vibration damper BAt the rear, at the flywheel end CMid-block between cylinders 3 and 4 DInside the oil pan sump
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   Answer: B. At the rear, at the flywheel end

   The DD platform uses a rear-mounted gear train at the flywheel end, which lowers gear-train noise and torsional excitation and keeps the front of the engine simpler.

2. Detroit Diesel DD16 Heavy-Duty

   The Detroit DD16 is best described as which engine configuration and displacement?

   AInline six-cylinder, 15.6 L BV8, 16.0 L CInline six-cylinder, 12.8 L DV6, 15.6 L
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   Answer: A. Inline six-cylinder, 15.6 L

   The DD16 is an inline six-cylinder diesel displacing 15.6 L, the largest engine in Detroit's DD platform (DD13 = 12.8 L, DD15 = 14.8 L).

3. Detroit Diesel Amplified Common-Rail Fuel

   The word "amplified" in Detroit Diesel's Amplified Common Rail System (ACRS) refers to what design feature?

   AA turbocharger-driven boost pump that raises rail pressure as boost climbs BA second high-pressure pump staged in series to double rail pressure CAn electronic driver circuit that steps up the voltage at the injector solenoid DA stepped amplifier piston inside each injector that multiplies rail pressure at the nozzle
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   Answer: D. A stepped amplifier piston inside each injector that multiplies rail pressure at the nozzle

   Each ACRS injector contains a hydraulic amplifier (intensifier) piston; rail fuel acts on its large area while the small area pressurizes fuel to the nozzle, roughly doubling pressure at injection.

4. Detroit Diesel Aftertreatment / One-Box

   The Detroit One-Box aftertreatment device combines which components in a single insulated housing?

   ADOC, DPF, SCR, and ammonia slip catalyst BDPF and DEF tank, with no SCR catalyst CTurbocharger, EGR cooler, and EGR valve DDOC and a muffler section, with no DPF
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   Answer: A. DOC, DPF, SCR, and ammonia slip catalyst

   The One-Box integrates the diesel oxidation catalyst, diesel particulate filter, SCR catalyst, and ammonia slip (clean-up) catalyst into one assembly, replacing the earlier two-canister layout.

5. Detroit Diesel DDEC Controls & DiagnosticLink

   On a DDEC VI engine, which controller is mounted on the engine and directly drives the fuel injectors?

   ACommon Powertrain Controller (CPC) BVehicle Electronic Control Unit (VECU) CMotor Control Module (MCM) DTransmission Control Module (TCM)
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   Answer: C. Motor Control Module (MCM)

   The engine-mounted MCM controls all engine functions and directly drives the injector solenoids, while the cab-mounted CPC handles the vehicle interface.

6. Detroit Diesel Detroit Axles

   Detroit single- and tandem-drive carriers transmit final-drive power through what type of gearset?

   AA hypoid ring-and-pinion set BA worm-gear set CA spur-gear set DA planetary reduction set
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   Answer: A. A hypoid ring-and-pinion set

   Detroit drive axles use a hypoid ring-and-pinion; the pinion sits below the ring-gear centerline for a lower driveline and greater tooth-contact area, giving higher torque capacity.

7. Detroit Diesel DT12 Automated Manual

   How is the Detroit DT12 best classified?

   AA 12-speed automated manual (AMT) with an automated single dry-plate clutch BA torque-converter automatic with planetary gearsets and a lockup clutch CA dual-clutch transmission (DCT) with two wet clutch packs DA continuously variable transmission (CVT) using a belt and pulleys
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   Answer: A. A 12-speed automated manual (AMT) with an automated single dry-plate clutch

   The DT12 is a mechanical countershaft gearbox with an automated single dry-plate clutch and full shift-by-wire electronic control, not a torque-converter automatic.

8. Detroit Diesel DD13 / DD15 Heavy-Duty

   The DD15 cylinder head is best described as which of the following?

   ASix individual bolt-on heads BTwo three-cylinder heads CA single one-piece cast-iron head DAn aluminum cross-flow head
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   Answer: C. A single one-piece cast-iron head

   The DD15 uses a single one-piece cast-iron cylinder head with a single overhead camshaft, a design concept carried over from the Series 60.

9. Detroit Diesel DD16 Heavy-Duty

   Top DD16 output in heavy-haul trim is approximately:

   A350 hp / 1,350 lb-ft B455 hp / 1,650 lb-ft C505 hp / 1,750 lb-ft D600 hp / 2,050 lb-ft
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   Answer: D. 600 hp / 2,050 lb-ft

   The DD16 tops out near 600 hp and 2,050 lb-ft, above the DD15's on-highway ratings, for severe-service work.

10. Detroit Diesel Amplified Common-Rail Fuel

    Compared with the peak pressure at the nozzle during injection, the pressure held in an ACRS fuel rail is approximately:

    ARoughly ten times higher BRoughly one-tenth as high CAbout the same DRoughly half
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    Answer: D. Roughly half

    Because the injector amplifier roughly doubles pressure, rail pressure runs near half of nozzle injection pressure (for example ~900 bar rail producing 2,000+ bar at the nozzle), which lowers pump and rail stress.