ASE T3

15. A medium truck uses a two-plate clutch and a synchronized transmission. It is difficult to shift into every forward gear. It also grinds when going into reverse. The MOST likely cause is: A. misadjusted clutch brake engaging too early B. a worn synchronizer unit C. dirty alignment lugs on the intermediate plate D. low viscosity transmission fluid

15. The correct answer is C. When the alignment lugs located on the intermediate plate get dirty, they can bind. This causes the clutch plate to fail to move away from the flywheel. The resulting friction counteracts the action of the synchronizers in lowering or raising transmission input shaft speed despite the engine speed being different. A clutch brake is used with non-synchronized transmissions. A worn synchronizer unit would only cause a problem with that synchronizer's gears. Low fluid viscosity will cause metal-to-metal contact of bearing and gear tooth surfaces.

21. The tires on one side of a drive axle are 2-in, taller than the tires on the other side. This condition could cause which of the following problems? A too much ring gear wear B. too much lubricant loss C. too much rear pinion bearing wear D. too much differential pinion (spider) and side gear wear

21. The correct answer is D. With two different size tires, the wheels will be rotating at different rpms-just as when rounding a corner-all the time. The spider or pinion gears and side gears are the ones that allow the wheels to rotate at different speeds.

24. There are three differentials in a tandem axle arrangement. The differential most susceptible for spin out failure is the A. forward drive axle main differential B. rear drive axle differential C. inter-axle differential or power divider D. all are equally susceptible to spinout failure

24. The correct answer is C. The inter-axle differential is positioned farther above the oil supply than either main differential, and therefore receives less lubrication. Also, all of its parts rotate at driveshaft speed, rather than at wheel speed, as in the case of the ring gear and its bearings. Spinout damage occurs when abnormal spider gear rotating speeds occur in a differential due to unusually great differences between wheel rotating speeds. The rotating speed of the pinion is not great enough to carry adequate lube up to the inter-axle differential.

25. A technician is measuring the torque required to rotate the pinion on a drive axle. He is using a spring scale in order to measure pinion bearing preload. He asks two fellow technicians to describe the correct procedure. Technician A says to start with the parts stationary, and read the spring scale very carefully while very gradually increasing the tension on it. This will give an accurate reading of the torque required to start the pinion rotating. Technician 8 says to get the pinion rotating and then pull it at a very steady slow speed while reading the scale. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B.

25. The correct answer is B. Rotating torque must be measured at a slow, steady rotating speed. Starting torque is noticeably higher than normal rotating torque.

43. As the oil temperature in the transmission increases level A. It raises the oil level. B. It lowers the oil level. C. There is no change in the oil level. D. none of the above

43. The correct answer is A. As liquid heats up, it expands. This requires that the proper grade and type of oil be used, the oil changed regularly, and the oil level maintained.

5. A truck with a high-torque, low-rpm engine exhibits a great deal of gear noise, as well as wear of the splines on various drivetrain parts. The truck uses a rigid disc clutch. All the U-joint angles are acceptable. The MOST likely cause of this problem is that the A Driver abuses the clutch by releasing it too rapidly B. Engine produces torsional vibration, which should be removed from the drivetrain by using a dampened disc clutch. C. Engine mounts are worn. D. Engine rating is such that the transmission requires the use of an oil cooler.

5. The correct answer is B. A rigid clutch cannot dampen the severe vibrations produced by modern high torque diesels. The only other source of the kind of vibration torque that would cause such damage would be misaligned driveshafts, and they have been found to be OK.

50. A clutch assembly is being replaced and heat marks have been found on the flywheel surface. Technician A says to try to remove the marks with an emery cloth first. Technician B says if the emery cloth fails to remove the marks, the flywheel must be replaced. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

50. The correct answer is A. Some heat marks can be removed using an emery cloth. However, if the marks cannot be removed with the cloth, the next step is to grind a new surface on the flywheel using the manufacturer's procedures and specifications. Only after grinding, and if the wear or damage still cannot be removed, should the flywheel be replaced.

52. Which of the following manual transmissions is the most popular in today's heavy-duty trucks? A. three countershaft B. two countershaft C. one countershaft D. none of the above

52. The correct answer is B. Most of the transmissions used in heavy-duty vehicles have two countershaft cluster gear sets to divide the higher torque necessary when moving heavier loads. This design, called the twin countershaft transmission, was originally developed to shorten the overall length of the gearbox, as the gears can be thinner when they operate this way.

53. On a heavy-duty twin countershaft transmission, which of the following gears are floating between the countershaft gears when they are disengaged? A. mainshaft B. countershaft C. input shaft D. output shaft

53. The correct answer is A. In the case of a twin or triple countershaft transmission, the mainshaft gear simply floats, suspended between the two corresponding countershaft gears

54. Technician A says that a constant mesh transmission can be shifted without depressing the clutch pedal if done precisely. Technician B says shifting without depressing the clutch pedal is called float shifting. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

54. The correct answer is C, both technicians are right. Many drivers shift constant mesh heavy-duty transmissions without depressing the clutch. If done with great skill and if the gear lever is not forced into the next position, float shifting can be accomplished with little or no transmission damage.

64. Technician A says an auxiliary transmission is used when a higher gear ratio is needed. Technician B says the auxiliary transmission is attached to the differential. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

64. The correct answer is A. Auxiliary transmissions are used to assist the main transmission when the extra gear reduction ratio or a higher gear ratio is needed. This type of transmission can be attached to or be part of the main transmission case, while others may be a separate unit, mounted between the transmission and the differential

8. A hydraulic clutch slave cylinder is being replaced. What should the technician do first? A. disconnect the clutch pedal pushrod B. remove the slave cylinder from its mounting C. disconnect the hydraulic line D. adjust clutch pedal free-play

8. The correct answer is A. The clutch pedal pushrod must be disconnected before servicing the slave cylinder. Damage to the master cylinder can occur if the pedal is accidentally depressed with the slave cylinder disconnected.

41. What is the proper fluid to use in a hydraulic clutch system? A. 5W-30 ol B. 90W gear oll C. 10W-30 ol D. DOT-3 brake fluid

41. The correct answer is D. The hydraulic clutch system is designed to use DOT-3 brake fluid only

56. How often should an over-the-road transmission typically have its oil changed? A. every 15,000 miles B. every 25,000 miles C. every 30,000 miles D. every 50,000 miles

56. The correct answer is D. Once the break-in period service has been completed, follow the recommended oil change interval suggested by the manufacturer or service manager, typically around 50,000 miles for on-highway use depending on the vehicle application

59. Which of the following is a function of the drive axle? A keep the suspension straight B. eliminate body roll C. permit the wheels to turn at different speeds D. all of the above

59. The correct answer is C. The drive axle's main function is to transfer engines power through 90 degrees or right angles to the drive wheels

65. Technician A says pre-adjusted wheel end systems are available as a complete package consisting of bearings, seals, and lubricant. Technician B says the movement (play) of the drum or rotor should exceed 0.030-in but not by more than 0.040-in. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

65. The correct answer is D, neither technician is right. Pre-adjusted systems are available with only the bearings and seals pressed into the hubs. Unitized wheel ends are a complete packaged system with bearings, seals and lubricant. The average wheel play should be less than 0.030-in. If the wheel play exceeds 0.030, suspect excessive wear or a bearing adjustment is needed.

66. The component used to slow down or speed up the rotating speed of the clutch disc, transmission input shaft, countershaft and its associated gears is called: A. clutch regulator B. transmission detent C. synchronizer D. idler gear

66. The correct answer is C. A synchronizer unit is typically used to slow down or speed up the rotating speed of the clutch driven disc, transmission input shaft, countershaft and its associated gears until both the main drive gear that will be in use and the transmission mainshaft are rotating at the same speed.

70. Which one of the following components should be suspected to be defective if the truck is able to start in any gear without depressing the clutch? A. safety switch B. starter kills witch C. ignition relay D. clutch damper switch

70. The correct answer is A. Most trucks have a safety switch mounted on the clutch pedal that prevents the engine from starting unless the clutch pedal is fully depressed. The ignition switch feeds the starter solenoid through the safety switch. When the clutch pedal is pressed, the switch closes and allows current to the starter solenoid. When the pedal is released, the switch and prevents current from reaching the starter solenoid. When the transmission is in neutral, the switch is bypassed so the starter can be engaged.

9. A 13-speed transmission exhibits wear problems in two places: the shift fork located on the yoke bar that shifts the splitter, and the surfaces of the shift collar that the fork bears against. The MOST likely problem is: A. a bad air seal in the overdrive shift unit B. engagement of overdrive while the transmission is in low range C. the driver preselects the splitter button, fip- ping it and then failing to complete the shift until some time later D. transmission lube oil diluted with water

9. The correct answer is C. Flipping the splitter button applies air pressure to the mechanism, causing the shifting fork to apply pressure to the gear. The pressure continues until the driver depresses the clutch or appropriately changes throttle position and allows the transmission to shift.

13. A truck's clutch has worn and developed severe slippage. Preliminary diagnosis indicates the clutch disc is worn out. Technician A says to check the con- dition (latness) of the pressure plate and flywheel when a new clutch disc is installed. Technician B says to check the condition of the pressure springs when a new clutch disc is installed. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

13. The correct answer is C, both technicians are right. Slippage of the original clutch most likely caused a lot of heat. Heat distorts the flywheel and pressure plate and weakens the pressure springs. No clutch can engage properly unless it is working against a flat pressure plate and flywheel, and has sufficient clamping pressure.

16. A driver complains of harsh clutch engagement when starting out. The clutch uses a ceramic facing. It has been examined and proved to be in proper mechanical condition. Technician A says the driver is starting in the wrong gear and using too much throttle. Technician B says the driver might be used to a clutch with an organic facing and recommends replacing the ceramic facing with an organic one, which would probably make the clutch engage more smoothly, although it could result in wear problems. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

16. The correct answer is C, both technicians are right. Ceramic clutch facings tend to grab more suddenly than organic ones, and they grab harder when bot. If the driver is starting in too high a gear, especially under loaded conditions going uphill, or if he is increasing the rpm of the engine above normal idle to get more torque, the clutch will overheat and become grabby. The second technician is correct in stating that an organic disc will engage more smoothly. Because the lining is softer, life will be shorter and longevity could be a problem unless the driver is very skillful.

18. Which of these statements about the diagram shown above is correct? A. All angles are OK and no adjustment is necessary. B. Angle 3 is wrong and should be adjusted C. Angle 4 is wrong and should be adjusted; also, angle 2 should be changed slightly to prolong the life of the U-joints on that shaft. D. Angle 5 is wrong and should be adjusted.

18. The correct answer is C. This is because of the position of the shaft between the auxiliary transmission and the front drive axle. The front drive axle housing should also be at an angle of 2 degrees so that the input and out put companion flanges will be parallel. This will ensure that the two joints of the shaft linking the front drive axle and auxiliary transmission will be parallel.

2. A manual shift transmission slips out of fifth gear. The MOST likely cause of this problem is: A. a broken detent spring B. too much shaft and gear spline wear C. worn countershaft bearings D. a chipped countershaft drive gear

2. The correct answer is A. The detent ball lightly holds the gear lever in place when a shift is complete. With a broken spring, there will be no pressure holding the ball in the detent located in the shift rail. Vibration can easily cause the direct drive (top gear) shift collar to slide and disengage. Answers B and D would cause grinding when shifting into gear, while answer C would cause a whining noise.

20. An older truck with a 2-piece driveshaft exhibits drivetrain vibration that is noticeable only in the lower drivetrain vibration that hard. Technician A gears when accelerating fairly hard. Technician A says the driveshaft is worn and needs to have the U joints rebuilt to smooth out their motion Technician B says the problem is very likely to be related to either poor design of the suspension or worn bushings. Who is right? A Technician A only B. Technician B only C. Both A and B D. Neither A or B

20. The correct answer is B. Torque, which is increased by driving in the lower gears, is causing the driveshaft operating angles to increase to the point where they are excessive. If the suspension bushings are worn, they should be replaced. If the bushings are OK, modifications should be made to the angles of the various components by shimming to reduce the driveshaft operating angles. Worn U-joints would likely show a problem when speed is increased.

22. A technician is rebuilding a drive axle. In what order should he make these adjustments? A. carrier bearing preload, backlash, pinion preload B. backlash, pinion preload, carrier bearing preload. C. pinion preload, carrier bearing preload, backlash D. pinion preload, backlash, carrier bearing preload

22. The correct answer is C. Backlash is affected by the preload adjustments. For example, play in the carrier bearings would allow the ring gear to shift back-and-forth: play in the pinion bearings would allow the pinion to slide forward-and-backward. Both these forms of play would be constantly changing backlash. Even without actual play, any change in preload would change the position of the pinion or ring gear.

23. The driver of a truck with a single rear axle says he hears too much rear axle noise only when the truck is pulling. Which of these is the MOST likely cause? A. worn axle shaft bearings B. worn wheel bearings C. won differential pinion (spider) gears D. worn ring and pinion gears

23. The correct answer is D. The ring and pinion gears carry load and are therefore directly affected by load. All the other possible sources of noise mentioned carry the same load whether the truck is pulling or not.

33. A driveshaft exhibits vibration. A road test reveals that the vibration ONLY occurs at certain speeds under normal loads, not all the way up and down the truck's speed range, and not under heavy load. The MOST likely cause is: A. driveshaft too heavy for the engine-transmission mounting system B. improper phasing C. the driveshaft is bent or inadequately balanced D. one or both of the U-joints is excessively worn

33. The correct answer is B. Improper phasing tends to provide vibration at a different frequency from the other problems. The type of vibration it produces causes the truck chassis to pass the vibration onto the cab only when the frequency is right. So vibration will be noticed only at certain speeds. Also, moderate torque loads can enable the driveshaft tubes to absorb and dampen the slight vibration

36. What is the purpose of changing the rear axle lubricant shortly after overhaul? A to thicken the viscosity B. to remove metal created during break-in C. to allow for proper bearing seating D. to take an oil sample

36. The correct answer is B. Manufacturers recommend changing the rear axle lubricant a short period after over haul. This will remove the high levels of metal created during the break-in of the new parts.

42. When inspecting for proper clutch linkage adjustments, Technician A says that the pedal free-play should be checked. Technician B says that the free play should be less than 1/2-in. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

42. The correct answer is A. As a rule of thumb, clutch pedal free travel should be adjusted to the manufacturer's specifications. This allows proper seating of the clutch disc.

44. Most manufacturers recommend an initial transmission oil change for highway vehicles after a break-in period of A. 1,000-1,500 miles B. 2.500-3,000 miles C. 3,000-4,000 miles D. 3,000-5,000 miles

44. The correct answer is D. Most manufacturers recommend an initial oil change after the transmission is placed in service, better known as the 'break-in period. This change is typically performed at 3,000-5,000 miles for over-the-road vehicles.

61. A truck with a splitter system uses all of the following components EXCEPT: A. splitter cylinder B. insert valve C. cross-shift valve D. regulator assembly

61. The correct answer is C. The splitter shift system uses a splitter cylinder and an insert valve in addition to a regulator assembly When the driver flips the splitter button, air passes through the control valve in the gearshift knob and to the center port of the cylinder cover via the insert valve, which shifts the splitter piston inside the cylinder to engage the splinter gearing

1. The driver of a truck says he hears a grinding noise when the transmission is in neutral and the truck is stopped; but the noise goes away when the clutch pedal is depressed. Which of these could be the cause? A. worn pilot bearing B. worn input shaft bearing C. worn clutch release (throwout) bearing D. worn auxiliary transmission countershaft bearing

1. The correct answer is B. The noise occurs only when the input shaft is rotating. The bearing handles the relative motion between shaft and case and thus works only when the shaft is moving. This occurs when the truck isidling with the clutch engaged. The noise goes away when the clutch pedal is depressed because the input shaft then stops turning and the bearing is stationary. The other symptoms would only occur when either the clutch is engaged or when the transmission is being shifted.

10. A truck has a single countershaft, synchronized transmission. The transmission exhibits a rough, uneven sound in only one of the lower gears. After disassembly, the technician finds that one gear tooth has broken off. There are no other signs of damage or abuse in the transmission. Technician A says the damage was at least partly the result of driver abuse (jamming the transmission into gear). Technician B says the problem is attributable at least partly to a defect in the gear itself. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

10. The correct answer is B. The gear teeth typically are designed so at least two are in mesh at all times. Thus, if damage resulted directly from abuse, more than one tooth would be affected.

11. A clutch has an organic lining. It fails to grab properly, and the driver complains of lack of power and engine racing. The proper place to start in correcting this problem is: A. adjust the clutch release bearing clearance to increase it and correct for internal wear B. adjust the clutch release bearing clearance to decrease it and correct for improper adjustment C. adjust the clutch external linkage D. replace the organic facing with a ceramic facing

11. The correct answer is A. If the clutch release bearing clearance is insufficient, the release mechanism will be counteracting the pressure of the springs that apply the clutch, reducing the torque it can carry. Adjusting the external linkage would have little affect on shifting since the release bearing clearance will be the same. If an organic clutch is replaced with a ceramic clutch, grabbing will improve.

12. The driver of a truck says he hears a grinding noise when he depresses the clutch pedal. Which of these is the MOST likely cause? A. no clutch pedal clearance B. worn clutch release (throwout) bearing C. low transmission lubricant level D. worn clutch plate

12. The correct answer is B. The throwout bearing is actuated only when the clutch pedal is depressed, and the bearing makes a grinding noise when it is worn. No clutch pedal clearance, low transmission lubricant level and a worn clutch plate would cause hard shifting.

14. A 2-plate pull-type clutch engages properly, but the transmission grinds when going into gear from neutral. Technician A says the cause could be a worn clutch brake. Technician B says the cause could be too little free-play. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

14. The correct answer is A. A worn clutch brake would prevent the clutch brake from slowing the rotation of the transmission gears for easy engagement. Too little free play would cause hard shifting from gear-to-gear.

17. Which of these is the MOST likely cause of a drive shaft vibration on a truck that has just had a U-joint replaced? A. driveshaft is out of phase B. U-joint was installed backwards C. U-joint was not lubricated. D. dirt on the driveshaft

17. The correct answer is A. An out-of-phase condition is the most common and severe cause of vibration. Also, improper phasing commonly occurs when a U-joint is replaced.

19. A single axle tractor has a relatively long wheel and a base and a one-piece driveshaft. It has recently begun exhibiting a driveline vibration problem. Discussion with the owner reveals that he recently replaced the original transmission, which had an overdrive top gear ratio of 0.87:1 with a unit having an overdrive top gear ratio of 0.74:1. Technician A says it probably just needs to have the U-joints overhauled. Technician B says the truck probably is operating in excess of the maximum speed for which the drive-shaft was designed. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

19. The correct answer is B. Every driveshaft layout has a critical speed, or highest speed at which it can operate. The longer the driveshaft, the lower the critical speed. A single axle tractor with a long wheelbase would have a very long, single driveshaft, giving a minimal critical speed. The recent change in transmission gear ratio would very likely allow the truck to travel at a speed that would operate the shaft past the critical rpm.

26. A technician has disassembled an axle. When ordering parts, he was asked the ratio, but there is no documentation available. To correctly determine the ratio: A. He should count the teeth on both pinion and ring gears and then divide the number of teeth on the pinion gear (the smaller number) into the number of teeth on the ring gear (the larger number). B. He should count the teeth on both pinion and ring gears and then divide the number of teeth on the ring gear (the larger number) into the number of teeth on the pinion gear (the smaller number). C. He can't determine ratio accurately by counting the teeth. He must reassemble the unit, make appropriate markings and rotate the pinion, counting revolutions until the ring gear has rotated exactly one revolution. D. He should contact the manufacturer and ask for the correct documentation.

26. The correct answer is A. Count the teeth on both pinion and ring gears and then divide the number of teeth on the pinion gear (the smaller number) into the number of teeth on the ring gear (the larger number).

27. When diagnosing drive problems that may be related to differential action, every differential on the truck must be checked out. Therefore, technicians should be aware that heavy trucks with tandem drive axles use differential(s)? A. one B. two C. three D. four

27. The correct answer is B. The reason relates to the requirements of providing power to four wheels. Tandem drive axles are used on the majority of heavy trucks to give continuous power at eight wheels. This helps ensure the truck's ability to carry maximum loads while also pro-also providing good traction and maximizing drive axle tire life. Thus, there is a differential in each of the drive axles.

28. Any of these could cause a transmission to jump out of direct gear, EXCEPT: A. bell housing not aligned B. engine crankshaft has too much end-play C. Shift lever extension too heavy D. clutch deo worn

28. The correct answer is D. A worn clutch disc has no effect on the rotation of the transmission or the alignment of its parts. A misaligned bell housing could cause jump out because the transmission would operate at an angle to the clutch. Excessive crankshaft end-play could cause vibration to be transmitted repeatedly to the transmission mainshaft, vibrating the shift collars involved and making them slide out of engagement. A heavy extension on the shift lever could pull on the gear lever and tend to slide the shift collars out of position.

29. The driver of a heavy truck with a 9-apeed transmission says it shifts OK, except that it grinds a bit when going from fourth to fifth or fifth to fourth (when the range shift occurs along with the main box shift). All of the following could be the cause EXCEPT A. The transmission air pressure filter regulator has a clogged filter or worn parts. B. The range shift air cylinder has worn seals C. The transmission fluid is of the wrong viscosity the viscosity is too heavy). D. The transmission is overheating

29. The correct answer is D. When overheated fluid gets too thin, it could tend to help synchronizer function rather than hindering it. A filter or regulator could be the problem because of supplying low air pressure to the shift cylinder, slowing the synchronization process. Abad seal on the shift cylinder could do the same because of leakage around the cylinder, lack of pressure on the piston surfaces, and consequent lack of mechanical force. Also, fluid that is too viscous prevents synchronizers from. Also, squeezing the fluid out between working surfaces, developing friction.

3. The shift lever on a single countershaft transmission is hard to move. Which of these is the MOST likely cause? A. bent shift rails B. galled sliding clutch gears C. worn detent springs D. too much mainshaft gear end-play

3. The correct answer is B. Galled surfaces on the sliding clutches would make it difficult for them to slide along the shafts and in and out of the gears. Bent shift rails and worn detent springs would cause the transmission to slip out of gear. Too much mainshaft gear end play would cause shifting to be next to impossible and the transmission will exhibit a growling noise.

30. A truck has a lot of gear noise when idling in neutral. A check of records indicates the original clutch was replaced with a dampened disc clutch of appropriate specifications about 200,000 miles ago. Which one of the following possible conditions is the LEAST likely to be the cause of the problem? A. The transmission is misaligned with the flywheel and engine crankshaft. B. The gear teeth are worn so that there is excessive backlash C. The engine has an injector or compression problem or is idling much too slowly, causing rough running. D. The clutch dampening springs have fatigued and can no longer dampen torsional vibration.

30. The correct answer is D. Chances are very great that the dampening springs, designed to last at least for the normal life of the clutch disc, are still OK. Misalignment of the transmission input shaft with the flywheel would be very likely to cause bearing problems and resulting noise. The wear described increases operating clearances, preventing normal dampening of vibration that occurs when the motion of operating parts is restrained. Any thing that makes a diesel engine run unevenly causes low frequency torsional vibrations that are easily transmitted to transmission parts.

31. The front differential carrier assembly on a tandem axle truck has been overhauled and the lower housing refilled. The technician should do all of these, EXCEPT: A. check the differential housing angle B. add oil to the inter-axle differential C. check the differential lockout operation D. check for leaks

31. The correct answer is B. The inter-axle differential has no separate oil supply. The technician should make sure the main differential has the correct oil supply, instead. Training for Certification

32. A universal joint has failed prematurely. The failure was so drastic that the bars on the cross are cracked almost all the way through. The MOST likely cause is A. improper lubrication maintenance B. overtorqued U-bolt retaining nuts C. too much load carried over a long period of time D. contamination of lube due to deteriorated seals, which in turn causes binding

32. The correct answer is C. Although all the other causes could overstrain the crosses, the bulk of the damage would tend to occur to the bearings, cross bearing surfaces and cups.

34. Which of the following problems is the LEAST likely cause of a differential being noisy only on turns? A. worn differential side gears and pinions B. won differential spider C. worn differential thrust washers D. a bent axle shaft

34. The correct answer is D. A bent axle shaft would be rotating and vibrating at almost the same speed or frequency whether the truck was rounding a corner or not.

35. Technician A says the outboard planetary axle has a separate oil supply. Technician B says the inboard planetary axle is used on most trucks. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

35. The correct answer is A. Outboard planetary axles need a separate oil supply to lubricate the additional gears at each wheel. The most common planetary drive axle found in trucks is the outboard, not the inboard planetary type.

37. Technician A says the PTO is designed to power accessories such as a dump body. Technician B says the transfer case redirects power to the front axle. Who is right? A. Technician A only Technician B only C. Both A and B D. Neither A or B

37. The correct answer is C, both technicians are right. The PTO is designed to power accessories through the transmission while the transmission is in neutral. It is an extension of the drivetrain that allows power to be mechanically transferred to the accessory via a separate driveshaft or pump. The transfer case is basically a transmission unit mounted into the driveline, where, by using gearing arrangements, engine power can be redirected. This engine power change of direction is normally used to supply power to a differential unit on the front axle for front-wheel drive.

38. Drive gears and pinions are tested and marked at the time of manufacture. This procedure is performed to: A. obtain gear teeth angles B. show the correct part number listing C. show where tooth contact is quietest D. designate the specific rear axle for their use

38. The correct answer is C. Drive gears and pinions are tested at the time of manufacture to detect machining variances and to obtain desirable tooth contact and quietness. When the correct setting is achieved, the gears are considered matched and a set of numbers, along with other identifying marks, are etched on the gear set.

39. A differential has been disassembled and crescent-shaped marks running along the length of the gear tooth have been found on some of the gears. Technician A says these marks indicate a lack of lubrication. Technician B says these are beach marks and are an indication of shock load. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

39. The correct answer is B. A crescent shaped mark that runs along the length of the gear tooth is called a beach mark and is an indication of a shock load. The tooth will actually bend at these marks, eventually causing breakage. Gears that have suffered lack of lubrication will show pitting or scoring.

4. In a transmission that has been taken apart, all of the bearings are excessively worn. Technician A says the cause could be moisture in the lubricant. Technician B says the cause could be too high an operating temperature. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

4. The correct answer is C, both technicians are right. Bearing wear often occurs when the viscosity of the gear lube is too low. Water dilutes the gear lube, thereby thinning it. Heat also thins the gear lube by breaking it down chemically.

40. A technician is installing a transmission and finds that the transmission housing will not seat flat against the clutch housing. What could be the cause? A. improperly lubricated release bearing B. worn clutch disc splines C. input shaft not seated in pilot bearing D. warped pressure plate

40. The correct answer is C. If the transmission housing does not fit flush against the clutch housing upon installation, chances are the tip of the input shaft is not properly aligned to fit into the pilot bearing.

45. The main function of the clutch brake is to: A. eliminate gear clash B. slow clutch rotation C. slow engine rpm D. none of the above

45. The correct answer is A. The clutch brake is used with non-synchronized transmissions to aid in making initial shifts into low or reverse gears without gear clash. It gradually stops the rotation of the transmission input shaft, countershafts and mainshaft gears, allowing smooth engagement (this is done by the synchronizers on transmissions equipped with them).

46. A driver is complaining that the clutch pedal does not return from the floor. All external inspections have been made and everything has been found to be OK. What else could be the cause? A. weak pressure plate springs A B. ceramic disc installed in place of organic disc C. warped flywheel D. worn out release bearing

46. The correct answer is A. If the clutch pedal hangs up or binds, and all external components are OK and the clutch pedal does not return from the floor, suspect pressure plate spring fatigue.

47. Technician A says that worm gears are very rarely used in truck drivetrains. Technician B says that spur gears are used for maximum strength with minimal weight. Who is right? A Technician A only B. Technician B only C. Both A and B D. Neither A or B

47. The correct answer is C, both technicians are right. Gears are classified according to the way the teeth are cut and the shape of the surface on which they are machined. Common types of gears are spur, bevel, helical, spiral, hypoid and worm gears. Worm gears are very rarely used in truck drivetrains, while hypoid gears are usually reserved for use in particular types of drive axles. Spur gears are commonly used where maximum strength and service life and minimal weight are required, and low noise level is not a primary requirement.

48. Technician A says that driveshaft torsional vibration can be caused by engine torque spikes. Technician B says torsional vibration is a result of a twisting motion of the driveshaft. Who is right? A Technician A only B. Technician B only C. Both A and B D. Neither A or B

48. The correct answer is C, both technicians are right. Torsional vibration is a twisting motion that causes the shaft to wind up and then straighten back out, all in a straight line. In fact, engine torque spikes are frequently the cause of torsionals, especially in modern, low rpm diesels.

49. When properly activated, a PTO experiences a whining noise. What could be the cause? A. defective overspeed switch B. excessive backlash between drive and driven gears PTO driveshaft out-of-phase D. missing gear teeth on PTO drive gear

49. The correct answer is B. Rattling or whining from the PTO is usually an indication of excessive backlash between the transmission drive gear and the PTO driven gear. If applicable, adjust the PTO mounting by installing a gasket of different thickness between the transmission and PTO housings

51. Technician A says the automated transmission inertia brake is used to help slow the countershaft on initial engagement when the clutch is out of adjustment. Technician B says that on an automated transmission, when a fault is detected, the driver can select which gears to drive in. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

51. The correct answer is A. On initial engagement, the countershaft must be slowed or stopped in order for the clutch to engage. This is achieved by using an inertial brake. When a fault is detected, the transmission will automatically go into a limited operation or "limp mode' in which the driver has no control.

55. Which of the following is the function of a synchronizer. A. make sure components don't synchronize at the same speed B. align the driveshaft with the differential C. ensure that components rotate at the same speed D. none of the above

55. The correct answer is C. A synchronizer unit is typically used to slow down or speed up the rotating speed of the transmission input shaft and countershaft and its associated gears until both the main drive gear that will be in use and the transmission mainshaft are rotating at the same speed. Simply put, its main function is to synchronize components that are rotating at different speeds. This is done so that a gear can be engaged (locked to the shaft) without gear clash.

57. Technician A says that it is possible to read fault codes by counting the blinks of an instrument panel display. Technician B says that some trucks have a diagnostic switch that activates fault codes. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

57. The correct answer is C, both technicians are right. It is often possible to read codes out of the TCU by counting the blinks of an instrument panel display Some trucks have a diagnostic switch, which when activated, allows the TCU to list the fault codes on the instrument panel display.

58. Semi-automated transmissions are designed to: A. have longer maintenance intervals B. be lightweight C. eliminate manual clutch actuation D. use an electronic shifter

58. The correct answer is D. Semi-automated transmissions incorporate an electronic shifter. The clutch is used.to start and stop the vehicle, to shift into reverse, or when the instrument panel display reads a signal from the TCU to use the clutch to break the driveline torque.

6. A truck fleet presently uses transmissions with an overdrive top gear ratio. It wishes to convert its trucks to the use of direct-drive transmissions. In order to get approximately the same number of engine revolutions per mile in top gear, the company would have to: A convert the gearing in its rear axles to a higher (numerical) ratio B. convert the gearing in its rear axles to a lower (numerical) ratio C. it need not convert (the same rear axle ratio will produce the same engine revolutions per mile) D. convert to lower-profile tires (which would turn more revolutions per mile)

6. The correct answer is B. On vehicles with overdrive. the engine turns more slowly than the transmission out put shaft and the driveshafts at any given speed. With a direct drive transmission, the engine must turn at the same speed as the driveshafts-in other words, with the same axle, faster. A numerically lower axle, requiring fewer revolutions of the driveshafts, would be the only means of bringing the required rpm of engine and drive shafts back down.

60. A crows foot pattern on the drive side of the ring gear teeth indicates A. excess pinion shaft end-play B. incorrect backlash C. lack of lubrication D. not enough pinion shaft end-play

60. The correct answer is C. A crowsfoot pattern on the drive side of the ring gear teeth or sharp edges on the teeth, indicates lack of lubrication or extended hand use of the axle. Ring gear teeth that are heavily worn or scuffed on the coast side only indicate either excess pinion shaft end-play or the axle is excessively used for braking. If there is a ridge partway down the drive side of the ring gear teeth, ring and pinion backlash is not correct.

62. A truck is exhibiting a constant flow of air from the exhaust port of the splitter cylinder cover. Technician A says the cylinder cover needs a new gasket. Technician B says the insert valve could be defective. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

62. The correct answer is B. A constant flow of air from the exhaust port of the cylinder cover most often indicates a faulty insert valve. Exhaust of air pressure should only occur briefly when the splitter control button is moved forward with the range box in high range.

63. Transmission temperature sensors are normally what type of sensor? A. transistor B. thermistor C. capacitor D. reluctor

63. The correct answer is B. Transmission temperature sensors are thermistor type sensors that change resistance according to temperature. As the temperature in the transmission increases, the resistance in the sensor decreases and this electrical signal is sent to the transmission temperature gauge.

67. Technician A says a single universal joint operating between two shafts turns at the same speed throughout 360 degrees of rotation Technician B says universal joints operate under a concept called torsional excitation. Who is right? A Technician A only B. Technician B only C. Both A and B D. Neither A or B

67. The correct answer is B. A single universal joint operating between two shafts at a given angle will not turn at an even and constant speed. During the first 90 degrees of rotation, the forward universal joint speed will increase. From the first 90 degrees to 180 degrees, the speed will decrease to again match the driving shaft speed. This sequence is again repeated respectively from 180 degrees to 270 degrees and from 270 degrees to 360 degrees. This fluctuation of speed is known as Torsional Excitation.

68. A truck that has just had its range shift slave valve replaced exhibits incorrect shifting. When the driver shifts into low range, the transmission actually operates in high range. Technician A says the lines between the range shift control valve and the slave valve could be crossed. Technician B says a constant flow of air from the exhaust port of the control valve is normal. Who is right? A. Technician A only B. Technician B only C. Both A and B D. Neither A or B

68. The correct answer is D, neither technician is right. If the air lines are crossed between the slave valve and range cylinder, the shifted position will not correspond with the range selection. A constant flow of air from the exhaust port of the control valve indicates lines are crossed between the control valve and slave valve.

69. Another name for a power divider would be? A. auxiliary axle B. range divider C. inter-axle differential D. differential reduction assembly

69. The correct answer is C. The power divider or interaxle differential divides the power between the two drive axles just as it is divided from side-to-side on a single drive axe. The total drive velocity of the rear drive axle can exceed or be less than that of the front drive axle due to imperfect tire matching and following a slightly different are on turns. For this reason, the power passes through an inter-axle differential or power divider.

7. Which one of the following operating conditions does NOT indicate to the technician that the truck would operate more reliably with a transmission oil cooler? A. truck is rated at 350 hp B. truck has a power rating of 450 hp C. truck cab has the maximum number of aerodynamic devices to smooth air flow D. truck normally cruises in an overdrive ratio of 0.85:1

7. The correct answer is A. Any truck rated less than 400 hp is normally approved for operation without a transmission oil cooler; only trucks of 400 hp and up require them.