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HET4 > 401F a&b: Transmission Service > Flashcards

401F a&b: Transmission Service Flashcards

1
Q

what would damaged torsional springs in the clutch cause

A

vibration or gear rattle complaint

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2
Q

what would driveline vibrations cause in the transmission

A

they would show up as gear rattle and are transmitted to the driver through the shift lever

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3
Q

what would driveline vibrations also cause

A

leaking output shaft seal and worn output shaft bearings .

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4
Q

what would gear shifting components that are loose, binding or out of adjustment cause

A

gear clashing and hard shifting

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5
Q

what are the common transmission complaints

A

vibration - slip out or jump out - hard shifting - gear clashing - excessive heat or noise

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6
Q

what is slip out or jump out

A

when the transmission moves to neutral on its own

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7
Q

when does slip out or jump out tend to occur

A

when torque is being applied to the drive line

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8
Q

some conditions that lead to slip out are

A

.transmission mounted eccentrically with the fly wheel pilot bearing
.worn mainshaft and out put shaft bearings
.insufficient pressure on the detent ( weak springs )
.excessive wear on the detent notch/ shift rail
.incorrect adjustment or excessive wear in the remote shaft linkage

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9
Q

when is jump out likely to occur

A

during rough or normal road conditions when there is no load on the driveline

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10
Q

what are some conditions that will cause jump out

A

. extra heavy and long shift levers that swing during operating over uneven terrain
. excessive movement between the transmission and shift linkage forcing the transmission out of gear
. weak or broken detent springs

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11
Q

what would cause hard shifting

A

the external shift linkage or the internal transmission components

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12
Q

what are some external linkage problems

A

. worn connections or bushings
. binding or improperly adjusted linkage
. lack of lubrication on the joints
. anything that obstructs the free movement of the shift lever

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13
Q

problems for hard shifting that occur inside the transmission are

A 
. a twisted mainshaft 
. bowed or broken mainshaft key 
. cracked housing 
. overtorqued shift block lock screws 
. sprung yoke bar 
. swelled areas of the yoke bar
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14
Q

what might cause hard shifting in first gear and reverse ONLY

A

that the first reverse spring-loaded plunger is not adjusted properly or is burred resulting in restricted movement

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15
Q

what will no properly double clutching between gears cause

A

gear clashing

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16
Q

what would be the problem if gear clashing occurs during shifting into first or reverse

A

incorrect clutch adjustment

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17
Q

what damage would be caused by a damaged/maladjusted clutch brake that is not working properly

A

the input shaft will not stop rotating and cause gear clashing

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18
Q

what are whine or squeal noises caused by

A

insufficient gear clearance or backlash

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19
Q

what would a growling noise be caused by in the transmission

A

damaged gear teeth or improper timing and improper installation of the countershaft gears

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20
Q

what would operating the transmission on a more than 12 degree slope cause

A

excessive heat due to lack pf lubrication

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21
Q

why should you never let the transmission hang by the input shaft

A

clutch disc damage will occur

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22
Q

why should you check the service manual before removing the cover during the shift tower removal

A

to see if the detent balls and springs will fly out at you

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23
Q

why should you change the oil in a transmission 24 to 100 hours after installation

A

because the components lap together and will cause excessive wear particles

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24
Q

what is Frosting

A

micro-pitting that appears as a band of off white discoloration formed in the middle of the tooth

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25
Q

what is off set frosting

A

micro-pitting that forms on one side of the gear tooth

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26
Q

what is healing

A

when mating teeth wear into each other and polish out the frosting . at this time no further wear will take place

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27
Q

what causes spalling in gear teeth

A

when the gear is subject to an extreme overload condition

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28
Q

scoring and galling is caused by

A

insufficient oil film between mating teeth resulting in very high surface temperatures causing welding and tearing of the gear teeth surface

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29
Q

what damage would sever shock loading or foreign object passing through the gear mesh cause

A

impact fractures

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30
Q

fatigue fractures are caused by

A

high stress over a period of time . can be identified by beach marks on the fractured area

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31
Q

what are stringers or gas pockets

A

weak points in the gear itself

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32
Q

when ever its determined that a gear must be replaced you must also

A

replace its mating gear

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33
Q

premature input shaft bearing failure or slip out in direct gear is often an indication of a problem with

A

engine and transmission mounts

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34
Q

leaking output shaft seals, worn output shaft bearings and broken synchronizer pins are often an indication of a problem with the

A

driveline

35
Q

worn input shaft splines that do not let the clutch fully release, cause gear clashing in which gears

A

first and reverse

36
Q

a power take off with mismatched gear sets or insufficient gear back lash will cause

A

whine or squeal

37
Q

why must the mating driveline parts be carefully marked before you disconnect the driveline

A

this will ensure that the driveline phasing and balancing will not be changed

38
Q

on a selective main shaft assembly, improper shimming could result in which two failures

A

too little running clearance do not provide proper lubrication
too much clearance causes excessive rattling due to vibrations

39
Q

what will improper installation of the dowels between the mainshaft housing and auxiliary housing will lead to

A

a misalignment problem and accelerated wear on components

40
Q

When could a shift lever slip out from gear?

A

During normal acceleration or deceleration

41
Q

Operator Complaint: Apply clutch pedal to shift and its hard to shift, grinding gears. What could be the fault?

A

Seized Pilot Bearing

42
Q

If a pilot bearing is seized what will happen when the clutch pedal is depressed?

A

No break in path of power, shaft continues to spin, cannot shift

43
Q

Why is end play important?

A

Allows for expansion

44
Q

Does the countershaft or mainshaft need more thrust washers?

A

Mainshaft needs more

45
Q

What type of bearings are used to support the mainshaft?

A

Anti-Friction bearings

46
Q

What is the main purpose of the thrust washers? (wear)

A

Reduce gear wear

47
Q

A blocker ring is usually made of what material?

A

Brass/Bronze

48
Q

Operator complains about grinding gears when shifting quickly. What could be the fault?

A

Damaged/Failed synchronizer

49
Q

Operator complains that shifting is becoming difficult. The technician finds the boot is torn on the shift lever assembly, what could be the fault?

A

Contamination around moving parts in the lower lever

50
Q

If a transmission breather clogs, what could be a result?

A

Input/Output seals fail - leak

51
Q

Jump out can be caused by worn detents or?

A

Long shifter

52
Q

Slip out can be caused by worn detents, worn linkage or?

A

Clutching teeth are worn out or a worn fork/collar

53
Q

What are the two types of gear teeth on sliding clutches?

A

Dove tail or straight cut

54
Q

What gears usually use a dove tail gear tooth on the sliding clutch?

A

4th and 5th

55
Q

Do auxiliary transmissions use helical cut gears or straight cut gear?

A

Helical gears to handle torque

56
Q

Operator complains of a whine/squeal, what could be the cause?

A

Insufficient clearances
PTO w/out backlash
mix matched gears

57
Q

What could cause a transmission to get stuck in gear?

A 
twisted mainshaft
worn shift tower housing
worn input shaft splines
misadjusted clutch/clutch brake
counter shaft brake
58
Q

What are some things that should be visually inspected when there is a transmission fault?

A

Engine and Transmission mounts
Clutch system condition
driveline condition
shift mechanism operation

59
Q

If an operator regularly coasts down hill with the clutch pedal depressed, what could be the fault they are causing?

A

Over heating

60
Q

True or False

A vehicle being driven under 32km/h constantly will have no faults?

A

False - unless adequate coolers are used

61
Q

What are three things that can cause a transmission to growl?

A

Broken gear teeth
Incorrect timing - will show up immediately after rebuild
Bad Bearings

62
Q

What type of bearing(s) support a mainshaft?

A

1 friction and 1 anti-friction

63
Q

What causes spalling on transmission gear teeth?

A

Overloading over a short period of time

64
Q

What can cause gear clash?

A

Improperly adjusted clutch
damaged clutch brake
seized pilot bearing
damaged splines on shaft

65
Q

A gear rattle can be cause by?

A

A rough running engine

66
Q

True or False.

Frosted gears should be replaced immediately?

A

False - normal wear

67
Q

True or False

Initial pitting is mild, usually 0.030” depth?

A

True

68
Q

What is used to measure clearance between gears on a selective mainshaft?

A

feeler blades

69
Q

Where would a selective washer be found on a NON-selective mainshaft assembly?

A

For reverse gear

70
Q

Chassis air supply pressure is at a minimum of?

A

90 PSI

71
Q

What is the final check on a transmission overhaul?

A

Road test - Leak check

72
Q

A green or blue plugs might be an indication of what in the transmission?

A

Synthetic oil

73
Q

After refiling a transmission with oil, when should oil level be rechecked?

A

After letting the engine run for a short period to fill the cooler and after the road test

74
Q

How large should a buffer zone be around a diesel electric hybrid?

A

1 m all around

75
Q

Who can repair hybrid vehicles?

A

Trained/certified personnel

76
Q

A “00” glove class is good to what voltage rating?

A

0.5kV

77
Q

A “4” glove class is good to what voltage rating?

A

36.0kV

78
Q

What must be worn over insulated rubber gloves when working with high voltage?

A

Leather protectors

79
Q

How often should protective gloves be checked?

A

Every use

80
Q

What air pressure is needed to activate the splitter cylinder?

A

58-63 PSI

81
Q

Upstream from the air filter/regulator, what should air pressure be (minimum)?

A

90 PSI

82
Q

How low does the voltage need to be before working on High voltage system?

A

Below 30 volts

83
Q

How is gas charge from an accumulator vented?

A

Connect a proper venting tool

84
Q

How many groves are on a non-selective main shaft?

A

3 groves

HET4 (44 decks)

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