270202 - Power Train

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What is the drive ratio of a drive that has a drive pulley with a diameter of 2 inches and a driven pulley with a diameter of 5.5 inches? Round the answer to two decimal places.

0.36:1 1.00:1 2.75:1 5.50:1

A sprocket with 45 teeth turning at 2800 rpm is driving a sprocket with 28 teeth. Find the rpm of the sprocket with 28 teeth. Round the answer to the nearest whole number.
1740 rpm 2800 rpm 4500 rpm 7080 rpm

If roller chain stretch due to wear exceeds what maximum tolerance, must the chain be replaced?
Greater than 1% or 2% Greater than 1.5% or 2.5% Greater than 2% or 3% Greater than 4% or 5%

Unlike chain drives, V-belt drives are typically considered unsuitable for which requirement?
Operation in hot environments. Low horsepower applications. Positive drive requirements, such as timing. Applications requiring tensioners to compensate for wear.

A simple gear train has a drive gear with 12 teeth and a driven gear with 24 teeth. What is the gear ratio, and what type of operational change is achieved?
0.5:1; Overdrive 1:1; Direct Drive 2:1; Reduction 24:1; Deep Reduction

A compound gear train consists of an input pair (18 teeth driving 54 teeth) and a second pair (18 teeth driving 72 teeth). What is the resulting total reduction ratio of the compound gear train?
4:1 8:1 12:1 18:1

When a large drive gear with 24 teeth turns at 1000 rpm and drives a small gear with 12 teeth, what is the resulting speed and torque output combination?
Speed decreases, torque increases. Speed and torque remain unchanged. Speed increases, torque decreases. Speed increases, torque remains the same.

In a gear train consisting of an external drive gear, three external idler gears, and an external driven gear, what is the final rotation of the driven gear relative to the drive gear?
Opposite direction, because the total number of gears is even. Opposite direction, because the last two gears always rotate oppositely. Same direction, because an odd number of gears are in mesh. The direction cannot be determined without knowing the ratio.

Compared to spur gears, single helical gears create axial/thrust loads during operation. What physical components are necessary to control these loads?
Split guide rings. Speed sensors. Thrust washers or bearings. Non-hunting gear assemblies.

Due to the tremendous amount of sliding contact and pressure developed between the teeth, Hypoid gear sets require which specialized lubrication type?
Automatic Transmission Fluid (ATF). Synthetic gear oils (GL-1 rated). A special extreme pressure (EP) type of lubricant. A multi-viscosity oil that reduces axial thrust.

Where is the friction clutch assembly located in a vehicle equipped with a manual transmission?
Between the driveshaft and the rear axle assembly. Between the output shaft and the engine crankshaft. Between the engine flywheel and the transmission input shaft. Between the clutch master and slave cylinders.

What is the explicit function of the torsional springs located within the hub of a spring-dampened clutch disc?
To cushion initial engagement against the flywheel. To provide clutch pedal free play adjustment. To absorb and dampen torque and engine power pulses. To apply the pressure plate against the flywheel.

A technician must avoid installing a flywheel from an externally balanced engine onto an internally balanced engine (and vice versa). Why is this critical?
To ensure the flywheel can absorb and dissipate heat effectively. To prevent the Marcel spring web from warping. Because part of the engine balancing is accomplished by a balance weight incorporated into the flywheel. To ensure the flywheel can rotate at high engine speeds.

Which clutch disc lining material is commonly used in heavy-duty truck applications because it provides very good resistance to slipping, despite potentially causing premature wear on the pressure plate and flywheel?
Organic linings (NAO) Semi-metallic linings Ceramic button linings Sintered bronze linings

What component, constructed of segmented, curved spring steel, provides cushioning during clutch engagement to prevent harshness?
Torsional Load Springs Belleville Springs Marcel Springs Clutch Release Levers

The small bearing located in the bore of the flywheel or crankshaft serves what primary purpose?
To carry the axial load applied by the release bearing. To absorb torsional shock during engagement. To pilot (guide and align) the transmission input shaft. To provide a friction surface for the clutch brake.

Clutch release bearings must be designed to withstand what type of specific load classification?
Radial load Axial load (Thrust) Centrifugal force Torsional vibration

What is the primary purpose of the blocking ring component in a synchronizer assembly?
To transfer torque directly from the gear to the output shaft. To act as a brake shoe to bring the output gear to the speed of the output shaft. To provide a neutral location for the shift sleeve. To lock out the selection of a second gear simultaneously.

In a transverse-mounted transaxle, what is the most significant physical difference compared to a manual transmission?
Transaxles use helical gears, while transmissions use spur gears. The output shaft runs parallel to the input shaft instead of directly behind it. Transaxles must always be electronically controlled. Transaxles require five shafts, while transmissions only require three.

What system, designed into the internal shift mechanism, is responsible for preventing the transmission or transaxle from hopping or jumping out of gear due to engine torque variations?
The Interlock system. The Synchronizer Unit. The Detent system. The External Linkage system.

The purpose of the interlock system in a manual transmission shift mechanism is to accomplish what goal?
Provide a positive feel when selecting a gear (detent function). Ensure the operator exerts pressure to engage first or reverse. Prevent the driver from selecting two gears at once. Lock the output gear to the synchronizer hub during the shift.

When a five-speed transmission is in Neutral, what is the state of the power flow and internal components?
All shafts and gears are stopped because the input shaft is disconnected from the engine. The input shaft is spinning, but all gears are stopped, and the output shaft is locked. The input shaft and all gears turn, but the output shaft does not, so no power is transmitted. The synchronizers are all locked to their respective gears, but the idler gear freewheels.

When the driver selects 4th gear (Direct Drive) in a simplified five-speed transmission, the synchronizer sleeve moves to lock the output shaft directly to which component?
The 4th output gear. The cluster drive gear. The input shaft. The cluster 4th gear.

To keep lubrication circulating, light-duty manual transmissions and transaxles rely on which system?
A pressure pump system feeding oil to galleries. A combination pressure and splash system. A splash system, where rotating gears throw oil onto components. An external oil cooler system.

The high torque handling capacity of a twin countershaft transmission is achieved partly because the mainshaft gear is suspended or "floating" between the countershafts. This floating design eliminates the need for what components between the mainshaft and the mainshaft gears?
Sliding clutches. Bearings (or bushings/shaft sleeves). Thrust washers. Mainshaft retaining rings.

The auxiliary section of a heavy-duty transmission is typically shifted using air signals. Which component in the range shift cylinder assembly prevents air from passing from one side of the piston to the other or into the transmission housing?
The yoke assembly. The range clutch. O-rings. The detent pin.

In the auxiliary section of a compound transmission, which type of gearing typically accounts for a large ratio change?
Splitter gearing. Range gearing. Deep reduction gearing (only available in Low Range). Overdrive gearing (always 1:1).

The main section of heavy-duty multiple countershaft transmissions is classified as what design type?
Synchronized, constant mesh, helical gear design. Synchronized, sliding gear design. Non-synchronized, constant mesh, sliding clutch design. Automated shift, synchronized constant mesh design.

The clutch brake is necessary for heavy-duty, non-synchronized transmissions for what purpose?
To prevent the mainshaft gears from floating away from the countershafts. To reduce the transmission of noise and vibration to the cab. To stop the input shaft from turning when the operator shifts into a starting or reverse gear. To lock out the inter-axle differential during a spin-out.

Which type of PTO actuation method allows the power takeoff unit to be safely engaged and disengaged while the vehicle is in motion?
Cable actuated PTO. Air actuated PTO (sliding gear). Clutch shift actuated PTO (hot shift). Electrically actuated PTO (solenoid controlled).

When installing a Power Takeoff (PTO), the gasket placed between the PTO and the transmission provides which two specific functional purposes?
Adjusts driveline angle and reduces vibration. Acts as a seal to prevent leaks and provides a way of setting the proper backlash. Increases the torque output and filters the gear oil. Transfers torque from the countershaft and dampens shock loads.

What critical action must the operator ensure before engaging a power takeoff (PTO) unit?
The main transmission must be shifted into Neutral. The clutch is disengaged and the transmission gears are not turning. The vehicle speed sensor must read 0.0 mph. The air shift cylinder must be in the Low Range position.

A five-speed main transmission section combined with a three-speed auxiliary transmission provides the operator with how many possible forward gear selections?
9 15 18 20

Conventional cross-and-roller U-joints cause the shaft they are driving to speed up and slow down as they transfer rotational motion through an angle. This condition is known as:
Constant velocity. Variable velocity. Proper phasing. Torsional dampening.

What is the normal maximum working drive angle recommended for a cross-and-roller universal joint (U-joint)?
5 ° 8 ° 12 ° 20 °

In Front-Wheel Drive (FWD) applications, torque steer is most often corrected by manufacturers using what method?
Replacing all fixed CV joints with plunging joints. Using an intermediate shaft on the long side to equalize halfshaft length. Mounting the transaxle assembly on a centre support bearing. Eliminating the use of the double offset joint.

The Rzeppa CV joint is classified as a fixed depth joint. Where is it most commonly used in FWD vehicles?
At the inboard end (at the transaxle). On the propeller shaft (midship). On the outboard end (at the wheel). As the centre support bearing coupling shaft.

Which type of plunging CV joint uses a three-trunnion spider with rollers running on needle bearings and is typically used at the inboard position (at the transaxle) of front-wheel drive vehicles?
Rzeppa Joint Tripod Joint (Tulip Joint) Double Cardan Joint Cross-Groove (Lobro) Joint

Since the Rzeppa joint is a fixed joint and does not allow for driveline length change, it must be used in conjunction with which other component type?
A fixed yoke A constant velocity U-joint A plunging joint or slip joint A cross-and-roller U-joint

To be phased correctly in a driveshaft assembly, the two universal joints must be aligned so that the yokes on the same shaft are in what orientation?
Rotated 90 ° relative to each other. Tapered toward the center support bearing. In the same plane (facing the same way). Aligned precisely to the master spline.

What is the fundamental purpose of the light-duty drive axle gear sets?
To allow the drive wheels to turn at different speeds when cornering. To provide a 90 ° change in the path of power. To provide a final gear reduction resulting in a torque increase and a speed decrease. To transmit torque from the differential case to the wheels.

In a semi-floating axle assembly, what is the sole function of the axle shaft?
Supporting the vehicle weight. Transferring axial and radial loads. Propelling the vehicle (transferring torque). Supporting the wheel end with two tapered roller bearings.

The large curvature of the gear teeth in a hypoid gear set causes what consequence during meshing?
It eliminates noise and vibration. It reduces the requirement for EP additives. It causes a great deal of side thrust. It ensures torque is always divided equally.

Which type of semi-floating axle bearing configuration requires the use of a C-lock on the end of the axle shaft to transfer side thrust?
Ball bearings Tapered roller bearings Straight roller bearings Pilot bushings

In a standard differential, when a vehicle is rounding a corner, the differential pinion gears rotate on their shaft to transfer lost motion from the inside wheel to the outside wheel. What component is required to balance the forces and ensure torque is split equally between the two axle side gears?
The thrust washer on the differential case. The differential case side bearings. The differential pinion shaft. The pinion position shims.

What specialized chemical additive is generally required for gear oil when a vehicle is equipped with a limited slip differential (LSD) assembly (Disc Clutch type)?
Anti-foaming agent. Extreme-pressure (EP) additive. Friction modifier. Viscosity stabilizer.

If the drive axle breather vent is restricted or plugged, what problem may occur?
Gear oil viscosity will increase dramatically. The differential clutch packs will fail to preload. Fluid leaks from any of the axle housing seals (due to excess pressure). The ring gear will fail to splash oil onto the pinion bearings.

A single-speed double reduction carrier assembly performs its second gear reduction through a set of:
Hypoid gears. Spur gears. Helical gears. Planetary pinion gears.

In a planetary two-speed drive axle assembly, when operating in High Speed, the overall gear reduction is provided through only which components?
The planetary gear set. The crown gear set (single reduction). The planetary gear set and the crown gear set (double reduction). The inter-axle differential assembly.

What does the Gross Axle Weight Rating (GAWR), which is the manufacturer's rating stamped on the axle, dictate?
The maximum permissible driveshaft speed. The construction of the housing, bearings, and wheel ends based on the weight the axle must safely carry. The torque multiplication capacity of the gear set. The type of lubrication required (splash or pressure).

What is the fundamental purpose of the inter-axle differential lockout assembly?
To allow speed differences between the two drive axle pinions during cornering. To provide maximum traction on dry road surfaces. To lock out inter-axle differential action and provide torque to both drive axles evenly. To ensure the bevel gear is constantly turning at the same speed as the input shaft.

During normal operation (lockout disengaged), how does the inter-axle differential assembly divide torque between the forward and rearward drive axle assemblies?
Torque is directed to the axle with the least traction. The torque split is variable depending on vehicle load. Torque is divided equally between the two drive axle assemblies. Torque transfer is stopped entirely if there is a speed difference.

The vast majority of drive axle assemblies are lubricated using which basic system?
Combination splash and pressure system. Dedicated pressure pump and external filter system. Splash lubrication system. Oil gallery and trough system only.

If a parts technician sells a customer the wrong type of gear oil and it is mixed with the existing lubricant in the drive axle housing, what is the consequence?
The fluid's viscosity rating will increase. The gear oil causes a breakdown chemically. The oil will resist rust and corrosion more effectively. The total fluid capacity of the housing is reduced.

What is the main purpose of four-wheel drive (4WD) and all-wheel drive (AWD) systems?
To increase fuel economy on long trips. To equalize the torque split between the inside and outside wheels. To increase traction on slippery road surfaces. To eliminate the need for a center differential.

The viscous coupling unit in a full-time transfer case is designed to lock up and deliver power to the axle with traction when the rate of slippage between the front and rear axles approaches what threshold?
2% 6% 10% 15%

When is a drive system typically classified as All-Wheel Drive (AWD)?
When it requires the driver to manually engage the front axle. When the system uses mechanical locking hubs. When the system is permanently engaged or automatically engaging four-wheel drive. When it only uses a chain drive to transfer power.

In the NV-246 electronic transfer case operating in Auto 4WD mode, the ATCM uses the Front Output Shaft Speed Sensor data to determine what critical operational metrics?
The engine load and vehicle speed (VSS). The rear output shaft speed and the encoder motor position. The amount of slip and the percent of torque to apply to the front axle. The required deep reduction gear ratio.

In the NV-246 system, when the transfer case is placed in 2HI, 4HI, or 4LO, what is the state of the transfer case motor lock circuit?
The lock circuit is energized, allowing the encoder motor to rotate. The motor lock circuit has no voltage provided to it, applying the lock. The lock releases to allow transfer of torque to the front propeller shaft. The lock circuit is energized to prevent gear clash.

Power is typically transferred to the front output shaft in a gear type transfer case operating in 4H or 4L via which mechanism?
Planetary gears and a center differential. A chain drive or gears. The Vehicle Speed Sensor (VSS) and an ATCM. A hydraulic multi-plate clutch only.

After operating a vehicle with automatic locking hubs in four-wheel drive, what procedure is required to unlock the hubs?
Stop the vehicle and shift the transfer case back into 2H. Drive forward one to two metres after shifting the transfer case to 2H. Completely stop the vehicle, shift out of four-wheel drive, and back the vehicle up one to two metres (three to six feet). Turn the selector switch on the dashboard to the "FREE" position.

All automatic transmissions consist of which three major functional sections?
Impeller, turbine, and stator. Oil pump, oil pan, and extension housing. Torque converter, planetary gear set unit, and hydraulic control system. Valve body, accumulator, and governor.

Which component of a lockup torque converter is used to provide direct drive from the engine to the transmission, eliminating slippage?
The impeller (pump). The one-way clutch (stator). The Torque Converter Clutch (TCC). The flex plate.

Vortex flow in a torque converter occurs when the turbine is turning at a lower rate of speed than the impeller. What operational characteristics accompany this flow?
Low heat, high output speed, and low torque. High heat, low output speed, and high torque. Freewheeling of the stator one-way clutch. The TCC is mechanically locked to the stator support.

The coupling point in a conventional torque converter is the point at which:
The torque multiplication ratio reaches 3.00:1. The turbine reaches 9/10 the speed of the impeller. The oil flow within the converter stops completely. The vortex flow is at its maximum.

What is the explicit functional purpose of the stator in a non-lockup torque converter?
To dampen engine torsional pulses. To provide a permanent mechanical lockup. To intercept the oil coming out of the turbine and redirect it back to the impeller to assist rotation. To act as a reservoir for fluid during the stall condition.

To achieve torque multiplication, the stator must be in which operational state during vehicle acceleration?
Freewheeling, allowing it to rotate clockwise. Held stationary (locked to the stator support). Rotating in the opposite direction of the impeller. Disengaged from the one-way clutch.

When the lockup clutch is in its engaged position, what is the state of the fluid flow through the torque converter?
Fluid flows inward, maximizing torque multiplication. Fluid flows outward, preventing clutch pressure buildup. Fluid flow stops completely, and pressure builds to a predetermined value. Fluid flows in rotary motion, providing a 1:1 coupling.

How is the process of locking the lockup torque converter clutch accomplished hydraulically?
By closing the oil cooler bypass valve. By reversing the oil flow, forcing fluid into the back side of the converter. By utilizing maximum vortex flow to apply the piston. By engaging the brake switch, which applies the apply piston.

The variable displacement vane pump output volume and system pressure are directly controlled by the operation of which component?
The crescent pump drive gear. The priming spring. The pressure regulator valve. The rotor guide ring.

Fixed displacement automatic transmission oil pumps (gear or rotor types) discharge an amount of oil that is proportional to what?
The required line pressure. Engine speed. The capacity of the torque converter. The shift solenoid duty cycle.

What is the purpose of the red dye added to most automatic transmission fluids?
To prevent foaming and oxidation. To enhance the fluid's high viscosity index. To distinguish it from engine oil. To maximize the fluid's high-frictional coefficient.

Automatic transmission fluid (ATF) consists primarily of base oil and performance additives. What is the approximate range for the percentage of base oil content?
70% to 75% 85% to 90% 50% to 60% 95% to 100%

What is the ideal running temperature range for automatic transmission fluid?
Below 55 °C (130 °F) 37 °C to 80 °C (100 °F to 175 °F) 90 °C to 120 °C (194 °F to 248 °F) Above 150 °C (300 °F)

Planetary gear sets are capable of handling large torque loads for their small size because:
They use helical gears which generate minimal end thrust. The torque load is distributed over several planet pinion gears, providing more teeth in contact. They operate almost exclusively in Direct Drive (1:1 ratio). They are made of stamped steel, reducing component weight.

In a simple planetary gear set, if the Sun Gear is held stationary and the Internal/Ring Gear is used as the input member, what operational condition is achieved?
Reverse Reduction Forward Overdrive Forward Reduction Reverse Overdrive

If the Sun Gear is held stationary and the Planet Carrier is the input member, what operational condition is achieved?
Reverse Reduction Forward Overdrive Forward Deep Reduction Neutral

Which of the following conditions achieves Direct Drive (1:1 ratio) in a planetary gear set?
Only the sun gear is freewheeling. The planetary carrier is held stationary. Driving any two members at the same speed or locking any two members together. The ring gear is held stationary and the sun gear is the input.

The freewheeling action of a one-way clutch serves what explicit purpose in the automatic transmission?
To lock the clutch support to the transmission case. To improve shift quality by eliminating a timing problem during band-to-band or band-to-clutch shifts. To provide a high degree of frictional drag in the freewheeling mode. To manually apply the piston when hydraulic pressure is insufficient.

What factor is primarily responsible for determining the torque capacity of a multiple-disc hydraulic clutch pack assembly?
The force provided by the return springs. The number of contacting surfaces (clutch plates and friction discs). The thickness of the steel plates in the stack. The diameter of the clutch apply piston.

A transmission band is always used in what capacity relative to the planetary gear set?
As a driving member to supply torque input. As a holding (reaction) member. As an output member to transfer torque to the mainshaft. As a torsional dampener to absorb shock.

What is the purpose of the small steel ball-type check valve found in some clutch pistons or drums?
To prevent the waved snap rings from flattening. To provide a vacuum break when the clutch is applied. To allow residual oil to escape when the clutch is released and turning at high RPM. To supply hydraulic pressure to the clutch plates.

What is the specific function of a waved steel plate or waved snap ring in a clutch pack assembly?
To act as a seal to prevent oil leakage from the drum. To act as a cushioning device to smooth engagement. To hold the clutch drum stationary to achieve reduction. To lock the clutch drum to the case splines.

Double-wrap bands provide greater holding ability than single-wrap bands primarily due to which characteristic?
They require greater hydraulic pressure to apply. They are made exclusively of semi-metallic friction material. The self-energizing or wrap-around action of its connecting segments. They are only used in Manual Low (L1) and Reverse (R) applications.

Single-acting servos are generally used for which transmission applications?
Those requiring a timed band release during upshifts. Applications that involve continuous high-speed rotation. Applications that do not involve automatic upshifts, such as Manual Low (ML) or Reverse (R). Those that require the servo to operate as a pressure accumulator.

When a double-acting servo releases the band, pressure is directed to the release side of the piston. What is the state of the apply pressure during this release?
Apply pressure is instantly exhausted to the sump. Apply pressure remains on the apply side of the servo piston. The apply pressure reverses direction to aid the release spring. The solenoid cuts off all hydraulic pressure to the servo.

Which type of band friction material is used in applications where the band is operating under static conditions (the drum is stationary when the band is applied), such as Manual Low or Reverse?
Organic (paper pulp or cellulose). Semi-metallic material. Stamped steel. Lathe-cut Teflon.

Which component is the most commonly used valve type in an automatic transmission when a valve must interconnect several passages or react to more than one pressure?
Check valve Ball-type relief valve Spool valve Bypass valve

What is the functional purpose of the throttle valve (TV) in a transmission hydraulic circuit?
To regulate mainline pressure based on output shaft speed. To provide maximum line pressure regardless of engine load. To provide pressure that varies with throttle opening or engine load. To restrict fluid flow to the governor valve.

When the engine vacuum is low (wide open throttle or WOT), what is the resulting hydraulic output pressure produced by the vacuum modulator?
Minimum pressure, close to 0 psi. Pressure proportional to the centrifugal force. High pressure equal to the incoming line pressure. Pressure equal to the exhaust port setting.

Shift valves are referred to as switch valves because they are spool-type valves that function as what device in a hydraulic circuit?
A pressure relief valve. A balanced (regulating) valve. A simple on/off switch. A continuously variable restriction valve.

In a four-speed automatic transmission, how many shift valves are required to control the gear changes?
Two shift valves. Three shift valves. Four shift valves. Five shift valves.

What is the output pressure produced by the governor directly proportional to?
Engine manifold vacuum. Throttle position. The rate of rotation (road or vehicle speed). The mainline pressure boost setting.

When a governor valve is fully open, what is the maximum pressure it can produce?
0 psi Pressure equal to the throttle valve pressure. Pressure equal to mainline pressure. Pressure determined by the spring tension only.

The position of the manual valve is determined solely by which type of input?
Hydraulic pressure from the pump. The opposing throttle valve pressure. Mechanical input from the driver (range selector lever). Electrical input from the Transmission Control Switch (TCS).

When pressure builds beyond the tension of the spring in a pressure relief valve, the valve opens and exhausts the excess fluid to which location?
The oil cooler. The pressure boost chamber. The sump. The manual valve inlet port.

What is the sole purpose of the Brake Switch signal when received by the PCM?
To signal the PCM to delay upshifts. To disengage the torque converter lockup clutch when the brakes are applied. To increase line pressure for aggressive downshifts. To automatically engage the park pawl.

If the electrical circuit supplying the Electronic Pressure Control (EPC) solenoid fails and the current flow is 0.0 amps, what hydraulic condition results in the transmission?
The shift solenoids automatically turn on. Minimum line pressure (0 psi). Maximum line pressure (the default setting). Throttle pressure is regulated by the vacuum modulator.

Which electronic module provides the necessary vehicle calibration data (based on axle ratio, transmission, tire size, and engine) to the ATCM via the on-vehicle network?
Vehicle Speed Sensor (VSS). Transfer Case Encoder Assembly. Powertrain Control Module (PCM). Throttle Position Sensor (TPS).

In electronically controlled automatic transmissions, the Vehicle Speed Sensor (VSS) replaces the function of which traditional component used in hydraulically controlled transmissions?
The vacuum modulator. The governor. The manual valve. The pressure relief valve.

Practice Exam 2 – Power Train