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ASE S3 Drive Train (School Bus) Practice Questions - ASE S3 - Drive Train (School Bus) Certification Exam
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Question
1
of 25
QUESTION 1 / 25
In an Allison automatic transmission used in a school bus, what component multiplies engine torque during vehicle launch?
Choose one answer below.
A
The torque converter
✓
B
The output shaft governor
✓
C
The transmission cooler
✓
D
The park pawl
✓
QUESTION 2 / 25
What allows torque multiplication to stop and the torque converter to act as a near 1:1 fluid coupling at cruising speed?
Choose one answer below.
A
The pump losing prime
✓
B
The stator freewheeling on its one-way clutch
✓
C
The turbine locking to the case
✓
D
The cooler bypass opening
✓
QUESTION 3 / 25
Technician A says the torque converter lockup clutch eliminates converter slip to improve fuel economy and reduce fluid heat. Technician B says lockup is normally applied in the lowest gear during launch. Who is correct?
Choose one answer below.
A
Technician B only
✓
B
Both A and B
✓
C
Technician A only
✓
D
Neither A nor B
✓
QUESTION 4 / 25
A school bus Allison transmission exhibits a shudder felt only when the converter lockup clutch applies at light throttle. The MOST likely cause is:
Choose one answer below.
A
A bent driveshaft
✓
B
A failed park pawl
✓
C
A loose differential carrier
✓
D
Worn or contaminated lockup clutch friction material
✓
QUESTION 5 / 25
Which transmission fluid specification is required for most current Allison automatics used in school buses?
Choose one answer below.
A
Allison TES 295 / TES 668 approved fluid
✓
B
Plain SAE 90 gear oil
✓
C
DOT 3 brake fluid
✓
D
SAE 40 engine oil
✓
QUESTION 6 / 25
When checking Allison transmission fluid level with the electronic oil level sensor and shift selector display, the fluid should be at:
Choose one answer below.
A
Cold with the engine off
✓
B
Operating temperature with the engine running and transmission in neutral on level ground
✓
C
Maximum RPM in drive
✓
D
Any temperature as long as the bus is on a hill
✓
QUESTION 7 / 25
A bus Allison transmission fluid is dark brown and smells burnt. This MOST directly indicates:
Choose one answer below.
A
Correct fluid condition
✓
B
Coolant in the fuel
✓
C
Overheating and clutch material degradation
✓
D
A worn U-joint
✓
QUESTION 8 / 25
In a planetary gearset, holding the ring gear, driving the sun gear, and taking output from the carrier produces:
Choose one answer below.
A
Direct drive (1:1)
✓
B
Overdrive
✓
C
Reverse
✓
D
Maximum forward gear reduction
✓
QUESTION 9 / 25
In a simple planetary gearset, reverse output is produced when the:
Choose one answer below.
A
Carrier is held, the sun gear is driven, and the ring gear is the output
✓
B
Ring gear and sun gear are locked together
✓
C
Carrier is the input and the ring is held
✓
D
Sun gear is held and the carrier is driven
✓
QUESTION 10 / 25
Direct drive (1:1) through a planetary gearset occurs when:
Choose one answer below.
A
The ring gear is held and the sun gear is driven
✓
B
Any two members are locked together so the unit rotates as one
✓
C
The carrier is held and the sun is driven
✓
D
All members are released
✓
QUESTION 11 / 25
Modern Allison transmissions in school buses primarily produce gear changes using:
Choose one answer below.
A
Manual clutch pedal operation
✓
B
A centrifugal flyweight only
✓
C
Clutch-to-clutch shift logic controlled electronically
✓
D
A torque tube
✓
QUESTION 12 / 25
During a clutch-to-clutch upshift, a delayed release of the off-going clutch while the on-coming clutch applies will MOST likely cause:
Choose one answer below.
A
A perfectly smooth shift
✓
B
No shift at all
✓
C
Reverse engagement
✓
D
Tie-up or harsh shift bind
✓
QUESTION 13 / 25
The TCM (Transmission Control Module) on a school bus Allison uses which input to help determine shift points?
Choose one answer below.
A
Throttle position and vehicle/output speed signals
✓
B
Tire tread depth
✓
C
Cabin temperature
✓
D
Door open sensor
✓
QUESTION 14 / 25
A school bus Allison transmission goes into a limited-operation 'limp' mode and the wrench/CHECK TRANS lamp is on. The technician should FIRST:
Choose one answer below.
A
Replace the torque converter
✓
B
Retrieve stored diagnostic trouble codes with a scan tool
✓
C
Replace the entire valve body
✓
D
Flush the cooling system
✓
QUESTION 15 / 25
Allison prognostics features such as oil life, filter life, and clutch (transmission health) monitors are intended to:
Choose one answer below.
A
Replace the need for any fluid checks permanently
✓
B
Increase engine horsepower
✓
C
Predict maintenance needs and component condition before failure
✓
D
Disable the torque converter
✓
QUESTION 16 / 25
A stall test on a school bus automatic transmission is performed to evaluate:
Choose one answer below.
A
Driveshaft balance
✓
B
Differential backlash
✓
C
U-joint working angle
✓
D
Torque converter and engine performance at maximum slip
✓
QUESTION 17 / 25
During a stall test, recorded stall speed is well BELOW the manufacturer's specification. This MOST likely indicates:
Choose one answer below.
A
An engine performance problem or a slipping stator one-way clutch
✓
B
A stuck-applied park pawl
✓
C
Excessive driveshaft runout
✓
D
A worn wheel bearing
✓
QUESTION 18 / 25
During a stall test, stall speed is significantly ABOVE specification. The MOST likely cause is:
Choose one answer below.
A
A binding U-joint
✓
B
Slipping transmission clutches or low fluid
✓
C
Excessive ring gear backlash
✓
D
A plugged air filter
✓
QUESTION 19 / 25
A hydraulic pressure test on an Allison transmission is used MAINLY to:
Choose one answer below.
A
Check coolant pH
✓
B
Measure tire pressure
✓
C
Verify main and clutch apply pressures against specification
✓
D
Set ignition timing
✓
QUESTION 20 / 25
Low main line pressure at all operating ranges on a bus automatic is MOST likely caused by:
Choose one answer below.
A
A bent driveshaft
✓
B
Worn brake linings
✓
C
A loose lug nut
✓
D
A worn oil pump, low fluid, or a stuck pressure regulator valve
✓
QUESTION 21 / 25
Technician A says an Allison output retarder uses fluid friction to slow the vehicle and creates heat that the cooling system must dissipate. Technician B says the retarder increases engine compression braking only. Who is correct?
Choose one answer below.
A
Technician A only
✓
B
Technician B only
✓
C
Both A and B
✓
D
Neither A nor B
✓
QUESTION 22 / 25
A school bus equipped with an Allison output retarder overheats the transmission only during long downhill braking. The technician should FIRST inspect the:
Choose one answer below.
A
Park pawl spring
✓
B
Transmission cooling system capacity and coolant flow
✓
C
Driveshaft U-joint phasing
✓
D
Differential ring gear backlash
✓
QUESTION 23 / 25
The transmission fluid temperature on a school bus Allison reads 280°F (138°C) and rising during normal level-road driving. The technician should:
Choose one answer below.
A
Ignore it because that temperature is normal
✓
B
Add brake fluid
✓
C
Investigate the cause, such as a restricted cooler, low fluid, or slipping clutches
✓
D
Disconnect the speed sensor
✓
QUESTION 24 / 25
What is the function of the transmission cooler in a school bus drivetrain?
Choose one answer below.
A
To pressurize the brake system
✓
B
To lubricate the U-joints
✓
C
To filter engine intake air
✓
D
To remove heat from the transmission fluid and maintain safe operating temperature
✓
QUESTION 25 / 25
Milky pink transmission fluid found during service MOST likely indicates:
Choose one answer below.
A
Engine coolant contamination, often from a failed cooler
✓
B
Normal new fluid
✓
C
Excessive lockup clutch wear
✓
D
Correct TES 295 appearance
✓
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