1. Torque converter operation, fluid coupling, stator torque multiplication, and
lockup clutch engagement strategy
2. Planetary gear set power flow, rotating versus stationary clutch packs, and
clutch-to-clutch shift sequencing
3. Hydraulic system fundamentals, main regulator valve function, pressure control
solenoids, and trim solenoid operation
4. Electronic control system architecture, TCM inputs and outputs, speed sensors,
throttle position sensor, and shift selector communication
5. Diagnostic trouble code interpretation, red versus amber check light meaning,
limp-home mode, and diagnostic response actions
6. Preventive maintenance procedures, cold and hot fluid level checks, fluid
condition indicators, and service interval determination
7. Retarder operation, enable conditions, ABS interaction, output speed
thresholds, and retarder request sensor circuits
8. Shift quality complaints, harsh or delayed engagements, stuck governor or
solenoid symptoms, and hydraulic versus electronic fault isolation
9. Emergency vehicle specific concerns, NFPA service intervals, severe duty
operation, and PTO integration with transmission controls
10. Model identification, Allison series designation meaning, forward speed count
interpretation, and generation-specific control features
EVT F6 — Allison Automatic Transmissions Exam
,1. In an Allison 3000/4000 Product Family transmission, what is the primary
function of the torque converter during initial vehicle acceleration from a
standstill?
A. To mechanically lock the engine crankshaft directly to the transmission input
shaft immediately upon throttle application
B. To provide hydraulic coupling between the engine and transmission while
allowing torque multiplication through stator deflection
C. To regulate fluid pressures supplied to the C1 and C2 clutch packs during range
engagement
D. To prevent the transmission control module from triggering a limp-home mode
under heavy load conditions
Correct Answer: B
Explained Notes:
The torque converter provides a fluid coupling that transfers power from the
engine flywheel to the transmission input shaft during launch . 1
During acceleration from a complete stop, the speed differential between the
impeller (pump) and turbine causes fluid deflection off the stator, resulting in
torque multiplication . 1
Option A is incorrect because lockup clutch engagement occurs later when
pump and turbine speeds are nearly equal, not immediately at launch . 6
Option C describes a valve body function, not a torque converter function.
, Option D is unrelated to torque converter operation; limp-home is an electronic
control response to faults.
2. Which three main elements make up the torque converter assembly in an
Allison automatic transmission?
A. Clutch, band, and servo
B. Sun gear, planet carrier, and ring gear
C. Pump (impeller), turbine, and stator
D. Valve body, governor, and modulator
Correct Answer: C
Explained Notes:
The torque converter consists of an impeller (pump) driven by the engine, a
turbine connected to the transmission input, and a stator that redirects fluid flow
. 6 10
Option A describes components of a band-type apply mechanism, not a torque
converter.
Option B describes planetary gear set components used for gear ratio changes.
Option D lists hydraulic control components, not torque converter elements.
3. What is the purpose of the stator in an Allison torque converter during vehicle
acceleration?
A. To drive the transmission oil pump and maintain main line pressure
B. To redirect fluid leaving the turbine back to the pump in a manner that multiplies
, engine torque
C. To mechanically lock the converter clutch when cruising speeds are achieved
D. To sense output shaft speed and transmit that signal to the transmission control
module
Correct Answer: B
Explained Notes:
The stator redirects fluid returning from the turbine so that it assists the
impeller, creating torque multiplication during acceleration . 6 10
Option A is incorrect because the pump (impeller) drives the oil pump, not the
stator.
Option C describes the lockup clutch function, which is a separate component.
Option D describes a speed sensor function, not a stator function.
4. When does the torque converter lockup clutch typically engage in an Allison
transmission used in emergency vehicles?
A. At engine idle only when the vehicle is stationary in Neutral
B. When pump and turbine speeds are nearly equal, reducing slip and improving
efficiency
C. During every downshift to provide engine braking assistance
D. Only when the transmission is operating in Reverse range
Correct Answer: B
Explained Notes:
lockup clutch engagement strategy
2. Planetary gear set power flow, rotating versus stationary clutch packs, and
clutch-to-clutch shift sequencing
3. Hydraulic system fundamentals, main regulator valve function, pressure control
solenoids, and trim solenoid operation
4. Electronic control system architecture, TCM inputs and outputs, speed sensors,
throttle position sensor, and shift selector communication
5. Diagnostic trouble code interpretation, red versus amber check light meaning,
limp-home mode, and diagnostic response actions
6. Preventive maintenance procedures, cold and hot fluid level checks, fluid
condition indicators, and service interval determination
7. Retarder operation, enable conditions, ABS interaction, output speed
thresholds, and retarder request sensor circuits
8. Shift quality complaints, harsh or delayed engagements, stuck governor or
solenoid symptoms, and hydraulic versus electronic fault isolation
9. Emergency vehicle specific concerns, NFPA service intervals, severe duty
operation, and PTO integration with transmission controls
10. Model identification, Allison series designation meaning, forward speed count
interpretation, and generation-specific control features
EVT F6 — Allison Automatic Transmissions Exam
,1. In an Allison 3000/4000 Product Family transmission, what is the primary
function of the torque converter during initial vehicle acceleration from a
standstill?
A. To mechanically lock the engine crankshaft directly to the transmission input
shaft immediately upon throttle application
B. To provide hydraulic coupling between the engine and transmission while
allowing torque multiplication through stator deflection
C. To regulate fluid pressures supplied to the C1 and C2 clutch packs during range
engagement
D. To prevent the transmission control module from triggering a limp-home mode
under heavy load conditions
Correct Answer: B
Explained Notes:
The torque converter provides a fluid coupling that transfers power from the
engine flywheel to the transmission input shaft during launch . 1
During acceleration from a complete stop, the speed differential between the
impeller (pump) and turbine causes fluid deflection off the stator, resulting in
torque multiplication . 1
Option A is incorrect because lockup clutch engagement occurs later when
pump and turbine speeds are nearly equal, not immediately at launch . 6
Option C describes a valve body function, not a torque converter function.
, Option D is unrelated to torque converter operation; limp-home is an electronic
control response to faults.
2. Which three main elements make up the torque converter assembly in an
Allison automatic transmission?
A. Clutch, band, and servo
B. Sun gear, planet carrier, and ring gear
C. Pump (impeller), turbine, and stator
D. Valve body, governor, and modulator
Correct Answer: C
Explained Notes:
The torque converter consists of an impeller (pump) driven by the engine, a
turbine connected to the transmission input, and a stator that redirects fluid flow
. 6 10
Option A describes components of a band-type apply mechanism, not a torque
converter.
Option B describes planetary gear set components used for gear ratio changes.
Option D lists hydraulic control components, not torque converter elements.
3. What is the purpose of the stator in an Allison torque converter during vehicle
acceleration?
A. To drive the transmission oil pump and maintain main line pressure
B. To redirect fluid leaving the turbine back to the pump in a manner that multiplies
, engine torque
C. To mechanically lock the converter clutch when cruising speeds are achieved
D. To sense output shaft speed and transmit that signal to the transmission control
module
Correct Answer: B
Explained Notes:
The stator redirects fluid returning from the turbine so that it assists the
impeller, creating torque multiplication during acceleration . 6 10
Option A is incorrect because the pump (impeller) drives the oil pump, not the
stator.
Option C describes the lockup clutch function, which is a separate component.
Option D describes a speed sensor function, not a stator function.
4. When does the torque converter lockup clutch typically engage in an Allison
transmission used in emergency vehicles?
A. At engine idle only when the vehicle is stationary in Neutral
B. When pump and turbine speeds are nearly equal, reducing slip and improving
efficiency
C. During every downshift to provide engine braking assistance
D. Only when the transmission is operating in Reverse range
Correct Answer: B
Explained Notes:
