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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
what is off set frosting
micro-pitting that forms on one side of the gear tooth
26
what is healing
when mating teeth wear into each other and polish out the frosting . at this time no further wear will take place
27
what causes spalling in gear teeth
when the gear is subject to an extreme overload condition
28
scoring and galling is caused by
insufficient oil film between mating teeth resulting in very high surface temperatures causing welding and tearing of the gear teeth surface
29
what damage would sever shock loading or foreign object passing through the gear mesh cause
impact fractures
30
fatigue fractures are caused by
high stress over a period of time . can be identified by beach marks on the fractured area
31
what are stringers or gas pockets
weak points in the gear itself
32
when ever its determined that a gear must be replaced you must also
replace its mating gear
33
premature input shaft bearing failure or slip out in direct gear is often an indication of a problem with
engine and transmission mounts
34
leaking output shaft seals, worn output shaft bearings and broken synchronizer pins are often an indication of a problem with the
driveline
35
worn input shaft splines that do not let the clutch fully release, cause gear clashing in which gears
first and reverse
36
a power take off with mismatched gear sets or insufficient gear back lash will cause
whine or squeal
37
why must the mating driveline parts be carefully marked before you disconnect the driveline
this will ensure that the driveline phasing and balancing will not be changed
38
on a selective main shaft assembly, improper shimming could result in which two failures
too little running clearance do not provide proper lubrication too much clearance causes excessive rattling due to vibrations
39
what will improper installation of the dowels between the mainshaft housing and auxiliary housing will lead to
a misalignment problem and accelerated wear on components
40
When could a shift lever slip out from gear?
During normal acceleration or deceleration
41
Operator Complaint: Apply clutch pedal to shift and its hard to shift, grinding gears. What could be the fault?
Seized Pilot Bearing
42
If a pilot bearing is seized what will happen when the clutch pedal is depressed?
No break in path of power, shaft continues to spin, cannot shift
43
Why is end play important?
Allows for expansion
44
Does the countershaft or mainshaft need more thrust washers?
Mainshaft needs more
45
What type of bearings are used to support the mainshaft?
Anti-Friction bearings
46
What is the main purpose of the thrust washers? (wear)
Reduce gear wear
47
A blocker ring is usually made of what material?
Brass/Bronze
48
Operator complains about grinding gears when shifting quickly. What could be the fault?
Damaged/Failed synchronizer
49
Operator complains that shifting is becoming difficult. The technician finds the boot is torn on the shift lever assembly, what could be the fault?
Contamination around moving parts in the lower lever
50
If a transmission breather clogs, what could be a result?
Input/Output seals fail - leak
51
Jump out can be caused by worn detents or?
Long shifter
52
Slip out can be caused by worn detents, worn linkage or?
Clutching teeth are worn out or a worn fork/collar
53
What are the two types of gear teeth on sliding clutches?
Dove tail or straight cut
54
What gears usually use a dove tail gear tooth on the sliding clutch?
4th and 5th
55
Do auxiliary transmissions use helical cut gears or straight cut gear?
Helical gears to handle torque
56
Operator complains of a whine/squeal, what could be the cause?
Insufficient clearances PTO w/out backlash mix matched gears
57
What could cause a transmission to get stuck in gear?
``` twisted mainshaft worn shift tower housing worn input shaft splines misadjusted clutch/clutch brake counter shaft brake ```
58
What are some things that should be visually inspected when there is a transmission fault?
Engine and Transmission mounts Clutch system condition driveline condition shift mechanism operation
59
If an operator regularly coasts down hill with the clutch pedal depressed, what could be the fault they are causing?
Over heating
60
True or False | A vehicle being driven under 32km/h constantly will have no faults?
False - unless adequate coolers are used
61
What are three things that can cause a transmission to growl?
Broken gear teeth Incorrect timing - will show up immediately after rebuild Bad Bearings
62
What type of bearing(s) support a mainshaft?
1 friction and 1 anti-friction
63
What causes spalling on transmission gear teeth?
Overloading over a short period of time
64
What can cause gear clash?
Improperly adjusted clutch damaged clutch brake seized pilot bearing damaged splines on shaft
65
A gear rattle can be cause by?
A rough running engine
66
True or False. | Frosted gears should be replaced immediately?
False - normal wear
67
True or False | Initial pitting is mild, usually 0.030" depth?
True
68
What is used to measure clearance between gears on a selective mainshaft?
feeler blades
69
Where would a selective washer be found on a NON-selective mainshaft assembly?
For reverse gear
70
Chassis air supply pressure is at a minimum of?
90 PSI
71
What is the final check on a transmission overhaul?
Road test - Leak check
72
A green or blue plugs might be an indication of what in the transmission?
Synthetic oil
73
After refiling a transmission with oil, when should oil level be rechecked?
After letting the engine run for a short period to fill the cooler and after the road test
74
How large should a buffer zone be around a diesel electric hybrid?
1 m all around
75
Who can repair hybrid vehicles?
Trained/certified personnel
76
A "00" glove class is good to what voltage rating?
0.5kV
77
A "4" glove class is good to what voltage rating?
36.0kV
78
What must be worn over insulated rubber gloves when working with high voltage?
Leather protectors
79
How often should protective gloves be checked?
Every use
80
What air pressure is needed to activate the splitter cylinder?
58-63 PSI
81
Upstream from the air filter/regulator, what should air pressure be (minimum)?
90 PSI
82
How low does the voltage need to be before working on High voltage system?
Below 30 volts
83
How is gas charge from an accumulator vented?
Connect a proper venting tool
84
How many groves are on a non-selective main shaft?
3 groves

HET4 (39 decks)

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