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HET Third Year Powertrain SAIT > 190303C > Flashcards

190303C Flashcards

Powershift and Automatic Transmission Mechanical/Electronic Components

1
Q

What are the two general categories of powershift and automatic transmission application?

A

cycling
hauling

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2
Q

how do these applications differ from each other?

A

by the arrangement of speeds and input/output direction that tranny offers

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3
Q

what are the two general categories of power shift and auto trannys based on design of internal gearing?

A

planetary type
countershaft type

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4
Q

what is the function of a transmission?

A

to modify engine power to propel heavy equipment through operating conditions it was designed for

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5
Q

what torque/speed relation would you need with heavy loads or a steep grade?

A

high torque, low speed

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6
Q

what torque/speed relation would you need with light loads or even ground?

A

low torque, higher speed

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7
Q

what is another function that transmissions provide?

A

power can be drawn off to drive components. (PTO)

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8
Q

What is the similarity between power shift and automatic transmissions?

A

they allow speed and direction change with no interruption to power flow from engine

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9
Q

How does a power shift tranny differ from an auto?

A

speed and direction changes are made at the discretion of the operator

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10
Q

all auto trannys are power shifts, but not all______ are autos

A

power shifts

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11
Q

how many reverse speeds are there on a power shift tranny?

A

as many as there are forward speeds

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12
Q

how does an auto tranny differ from a power shift?

A

spend changes are made independent of the operator action

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13
Q

how does an auto tranny make shifts?

A

receives info from ground speed and operator demand for power

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14
Q

what application uses power shift trannys?

A

cycling applications (repeated forward and reverse)

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15
Q

what units perform cycling applications?

A

loaders, dozers

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16
Q

what application uses auto trannys?

A

hauling applications

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17
Q

what does an auto tranny allow the operator to do?

A

focus their attention on maneuvering the machine

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18
Q

the gears used in planetary gear sets are in constant mesh, what does this prevent?

A

grinding and missed shifts when changing gears

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19
Q

a smaller, more compact planetary gear set is capable of transmitting the same amount of torque as a larger spur gear set because gear tooth loading is spread among all of the contact points in the gear set
T or F

A

True

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20
Q

why can smaller bearings and thrust washers be used on planetary gear sets?

A

axial and radial thrust loads are offset in a planetary set

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21
Q

planetary gear sets are extremely versatile in that they are capable of providing many _____ of speeds and directions particularly when multiple sets are used

A

combinations

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22
Q

Why are planetary gear sets used in heavy equipment power shift and auto shift trannys?

A

to modify torque and speed from engine

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23
Q

What gear style is usually seen on planetary gears?

A

straight cut spur or helical

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24
Q

what can the planetary carrier metal be made from?

A

cast iron, aluminum, steel

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25
Q

what do planetary gears commonly rotate on to reduce friction between gears and pinion shafts?

A

needle bearings

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26
Q

how is end thrust absorbed between gear ends and carrier?

A

on brass or steel thrust washers

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27
Q

what conditions can a simple planetary gear set create?

A
  1. reduction in fwd ranges
  2. reduction in reverse ranges
  3. direct drive
  4. neutral
  5. overdrive in fwd and reverse
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28
Q

what does gear ratio refer to?

A

of revolutions the input (drive) gear makes to complete one revolution of the output (driven) gear.

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29
Q

what are planetary pinions only used for?

A

transfer torque or change direction

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30
Q

what is gear reduction?

A

input speed is higher than output speed

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31
Q

what is overdrive?

A

torque reduced, speed increased

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32
Q

what is neutral/freewheeling?

A

power input but no power output

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33
Q

What are two speed reduction conditions?

A

first speed slow, second speed fast

34
Q

what are two overdrive conditions?

A

first speed slow, second speed fast

35
Q

what are two reverse speed conditions?

A

first speed reduction, second speed overdrive

36
Q

When does first speed reduction occur?

A

when the sun gear drives the carrier. smallest turning biggest. ring held

37
Q

when does second speed reduction occur?

A

when ring gear drives carrier. medium turning biggest. sun held

38
Q

what is a constant fact in planetary overdrive?

A

carrier being input member is always an overdrive

39
Q

what is a constant fact in planetary reduction?

A

carrier being the output member is always a speed reduction

40
Q

when does a first speed overdrive occur?

A

when carrier drives ring gear. sun held. biggest driving medium. mild

41
Q

when does second speed overdrive occur?

A

when carrier drives sun. biggest driving smallest. ring gear held

42
Q

what is a constant fact in planetary reverse?

A

carrier being held is always a reverse condition

43
Q

when does a first speed reverse occur?

A

sun drives ring gear. small driving medium. carrier held. reduction

44
Q

when does second speed reverse occur?

A

ring gear drives sun. medium driving smallest. carrier held. overdrive

45
Q

what are 2 ways to achieve neutral from a single planetary set?

A
  1. when there’s an input but no held member
  2. when there’s no input to gear set
46
Q

what are 2 ways to achieve direct drive from a single planetary set?

A
  1. locking 2 members together
  2. driving 2 members at the same speed (rpm) in the same direction
47
Q

all clutches are hyd applied, ______________

A

spring released

48
Q

what do clutches hold together in a planetary tranny?
what do brakes hold together in a planetary tranny?

A

2 components together

a component to the housing

49
Q

What is a quick way to remember what clutches/brakes are held for reverse?

A

first clutch, last brake

50
Q

what is the definition of a differential planetary gear set?

A

has a simple planetary with three rotating members, for dual input single output

51
Q

What happens to carrier speed when the sun and ring gear are turning the same direction?

A

carrier speed always in between both speeds.

52
Q

when the sun and the ring gear rotate in same direction, are there more or less teeth?

A

less teeth per rotation

53
Q

what does a rotating clutch do?

A

hold 2 components together, rotates with components

54
Q

what does a stationary clutch do?

A

hold component to tranny housing. “brakes” internal gear

55
Q

the output speed and torque of the differential planetary set with sun and internal gear inputs is determined by?

A

tooth speed of the sun and ring gear

56
Q

what does tooth speed refer to?

A

number of teeth passing by a given point in a given period of time. measured in teeth per second.

57
Q

if ring gear is rotated in opposite direction of sun gear, what does the carrier speed do?

A

decreases

58
Q

if ring gear is rotated at an equal negative tooth count speed to the sun gear, what does the carrier do?

A

carrier speed goes to 0

59
Q

rotating the ring gear in reverse to the sun at a higher speed causes the carrier to?

A

start to travel in reverse as well

60
Q

a direct drive within a planetary set exists when?

A

2 rotational speeds are equal, not tooth speed.

61
Q

if tooth speeds are equal in opposite directions, what is the carrier doing?

A

carrier is not moving

62
Q

All transmission clutches are _____ released?

A

spring

63
Q

where do tranny clutches get their oil from?

A

tranny charging pump

64
Q

what are 2 types of clutch discs used?

A

clutch discs (friction discs)
clutch plates

65
Q

what are clutch discs?

A

made from sintered bronze or composite, steel discs that have friction material bonded to them.

66
Q

what do the grooves on friction discs serve as a purpose for?

A

when disc is disengaged, allows oil to lubricate the groove lines
when disc engaged, allows oil to escape from grooves

67
Q

what is the purpose of clutch disc teeth?

A

spline to the compound to be held reactionary

68
Q

what are clutch plates?

A

located between every pair of clutch discs. provide a reaction surface where the clutch discs can act

69
Q

what are the tangs on the outside of the clutch plates for?

A

holding a component stationary ( to tranny housing)

70
Q

what are teeth on the outside of the clutch plates for?

A

spline to a clutch drum to hold 2 components together

71
Q

what is used to apply the clutch?

A

hyd actuated pistons

72
Q

what type of seal is common on a clutch piston?

A

lip seal

73
Q

what is the difference between manual and power shift trannys regarding the gears being held?

A

gears in power shift/auto are held to their countershafts with multiple disc oil applied clutches rather than mechanical clutches

74
Q

do countershaft transmissions use stationary clutches?

A

no, only rotating

75
Q

what are high-low countershaft units for?

A

providing various speed ratios, from deep reduction, direct drive, or overdrive.

76
Q

where do the clutch plates and discs spline to in a high-low countershaft unit?

A

clutch plates spline to the drum
clutch discs spline to the hub on the output shaft

77
Q

the planetary gear set component that meshes with the sun and internal gear is called the planet carrier
T or F

A

False
it is the pinions not the carrier

78
Q

what condition is it when both internal and sun gear rotating forward at the same tooth speed?

A

reduction

79
Q

what condition is it when internal gear rotates forward and sun gear rotates in reverse at same tooth speed as internal?

A

neutral

80
Q

wha condition is it when internal gear is rotating in reverse at a much higher tooth speed than the sun gear is rotation forward?

A

reverse

81
Q

what condition is it when the internal gear and sun gear are rotating forward at equal rpm?

A

direct drive

HET Third Year Powertrain SAIT (8 decks)

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