190303B Flashcards
Torque Converter Fundamentals and Service (120 cards)
1
Q
What do torque converters act as?
A
coupling devices, increase torque received from engine
2
Q
What is the principle behind hydrodynamic drives?
A
energy transfer from one component to another through fluid motion
3
Q
what are other names for hydrodynamic drive?
A
fluid couplings or fluid clutches
4
Q
What is the principle behind hydrostatic drives?
A
use fluid under pressure to achieve drive
5
Q
Energy transfer in a fluid coupling depends on three things:
A
Volume, Velocity, Viscosity Rating
6
Q
What is volume controlled by in an energy transfer?
A
physical size of impeller (pump) vane size, number of vanes, structure of vanes
7
Q
What is velocity controlled by in an energy transfer?
A
physical size of converter, actual size of the vanes and angles of vanes, speed of impeller
8
Q
What are the two elements that make up a fluid clutch?
A
impeller and turbine
9
Q
how does an impeller and turbine work as a coupling device?
A
transmits torque from an engine to driveline or directly to a tranny through moving fluid (kinetic)
10
Q
What is kinetic energy?
A
energy of motion
11
Q
how is kinetic energy created in a fluid coupler?
A
from the impeller
12
Q
what energy conversions does the turbine create?
A
kinetic to mechanical
13
Q
Where does the impeller receive torque from>
A
the engine flywheel, driven by flywheel.
14
Q
What causes the oil brought into the impeller to be moved outward?
A
centrifugal force
15
Q
what energy conversions does the impeller create?
A
mechanical to hydraulic/fluid energy
16
Q
Advantages of fluid couplers?
A
No mechanical connection
Shock absorption (created from sudden engine torque)
Gradual start up of a load
17
Q
Where is slippage the highest in a fluid coupler?
A
at low speeds
18
Q
why does slippage occur?
A
from the use of oil as a torque transfer medium
19
Q
Disadvantages of fluid couplers?
A
Efficiency lost from slippage
Slippage creates heat
Can’t get to a 1:1 ratio bc of slippage
Fluid couplings can transmit torque, but can’t increase or multiply
20
Q
Why does a fluid coupling unit not transfer 100% of the input torque?
A
bc both members in a fluid coupling have straight radial blades
21
Q
All torque converters are fluid couplings, but
A
all fluid couplings are not torque converters
22
Q
What is vortex flow?
A
flow of oil from impeller to turbine, back to impeller. circular movement like a spiral
23
Q
When does vortex flow happen?
A
when turbine is turning at a lower speed than the impeller.
24
Q
characteristics of vortex flow?
A
high heat, low output speed, high torque
25
what phase is vortex flow?
converter
26
What is rotary flow?
oil flows in same direction as the impeller is turning.
27
When does rotary flow happen?
when impeller and turbine are turning at almost the same speed. when impeller, turbine, and oil move together
28
characteristics of rotary flow?
low heat, high output speed, low torque
29
what phase is rotary flow?
coupling
30
Where is a split guide ring?
in the impeller and turbine, its a half shaped donut in the middle of the unit above the vanes (oil passes beneath it)
31
Purpose of a split guide ring?
prevent turbulence within the unit (smooths and directs oil flow)- laminar flow
32
What is a torque converter?
a fluid coupler with a third element: a stator
33
Can a torque converter multiply torque received by engine?
yes no shit
34
What are the energy conversions when using a torque converter?
mechanical (engine), into kinetic fluid energy, into mechanical energy (tranny or driveline)
35
What is a remote torque converter?
a torque converter not mounted directly to the engine, uses a short drive shaft in-between
36
what is the impeller element often referred to as?
pump element
37
How is the impeller connected?
to the engine flywheel (input). turns whenever flywheel is turning
38
purpose of having angled vanes on the impeller?
increases force and accuracy of fluid flow onto vanes in turbine element
39
how is the turbine connected?
bearing mounted in rear of torque converter housing, drives output shaft. physically sits closer to the flywheel
40
What's another name for a stator?
reaction member
41
purpose of a stator?
change direction of oil flow to assist in torque multiplication
42
what does increasing torque multiplication do for the torque converter?
increases efficiency
43
how does the change in direction allow kinetic energy to be used?
if energy isn't used in first pass of oil, that kinetic energy in oil goes back to impeller and gains even more energy as it's flung around again to increase the velocity of the oil
44
what does increasing the velocity of oil do in relation to torque?
increases engine torque by approx 2.00:1 to 3.00:1 ratio
45
what does the exact amount of torque multiplication depend on in a stator?
angle of the vanes in the elements
46
What torque condition is happening when the impeller rotates faster than the turbine and the stator is stopped?
torque multiplication
47
how does torque multiplication happen in a torque converter?
kinetic energy in the fluid leaving the stator gets sent back to the impeller and increases torque. recirculating fluid with kinetic energy
48
why do you need an overrunning clutch?
to prevent oil from turning the stator in the opposite way of impeller motion, reducing the torque
49
two types of stators?
fixed and freewheeling
50
how is a fixed stator positioned in the housing?
attached to converter housing stub shaft, does not move. splined to a sleeve.
51
can a fixed stator achieve rotary flow?
no. that means its a single phase converter
52
what is a freewheeling stator?
a stator with an overrunning clutch.
53
what stage is a freewheeling stator turning at and stopped?
freewheels in coupling phase
stationary in converter phase (torque increase required)
54
When does the freewheeling stator lock up?
when the turbine speed is lower than impeller speed
55
how many conditions does a freewheel stator have?
two (locked and freewheeling) so its a two phase converter
56
what does a lockup clutch do?
mechanically connects turbine and impeller to eliminate small amount of slippage.
57
what is a benefit of using a lockup clutch?
1:1 drive ratio for fuel efficiency.
58
when should direct drive be used?
when machine is empty, on level ground, or at high speed low torque.
59
how can the lockup clutch be activated?
manually, pneumatically, hydraulically, electrically
60
how does a lockup clutch work?
friction surface area pressing together, actuated by hydraulic pressure at the back of the piston pushing them to the turbine
61
When is maximum ratio accomplished in a torque converter?
at stall
62
when is minimum ratio accomplished in a torque converter?
when impeller and turbine are at approx the same speed
63
What is a phase?
relationship of the impeller and turbine relative to energy transfer
64
what is a stage?
number of times oil strikes the turbine before returning to impeller
65
3 phases?
converter, coupling, lockup
66
What is the converter phase?
occurs when turbine is slower than impeller (vortex flow)
67
what is the coupling phase?
turning turns approx same speed as impeller (rotary flow)
68
what is lockup phase?
turbine and impeller are locked to each other mechanically
69
how are stages classed?
number of turbine elements
70
what kind of stators do multi-stage converters have?
fixed, always in converter (vortex) phase
71
what is stall speed?
turbine stopped, impeller turning at rated engine speed, or when turbine and impeller at at the greatest difference in speed
72
What is a downside of stall?
high heat
73
a coupling phase, converter phase, and stall speed are considered to be what in a torque converter unit?
functional changes
74
purpose of a variable capacity torque converter?
increase or decrease torque capacity within its ratio range according to torque demand
75
3 types of variable capacity converters?
multiple impeller, multiple turbine, variable pitch stator
76
how does a multiple impeller work?
first impeller attaches to flywheel, constantly driven, other freewheels. second one controlled when piston pushes 2 together
77
when would you use the multiple torque impeller?
for when you need high torque
78
how is the benefit of using a multiple impeller achieved?
inner impeller send oil to other impeller, more circumference. oil needs to go faster to reach outer blades, so a change in velocity is created
79
how do multiple turbines work?
2 turbines connect with an overrunning clutch. only use 2 when needing high torque
80
How do variable pitch stators work?
changing angle of stator vanes changes amount of vortex flow= more or less torque
81
when is the highest torque produced on a variable pitch stator?
when its in the open position. smaller piston pushes bell crank and opens vanes= proper vortex flow
82
what does the charge pump do on a torque converter circuit?
deliver oil to converter and tranny
driven by impeller or off flywheel
83
what does the converter inlet relief valve do?
protects converter from excess pressure
main pressure control
84
what does the pressure regulating valve do?
maintains working pressure in converter.
normally closed but always open
prevents cavitation and aeration
on converter outlet
85
where is the temp sender gauge located?
converter outlet port
86
what kind of oil should be used in a converter?
light oil. ATF, or diesel (early models)
87
what happens if oil is too heavy in a converter?
it could cause converter to not use a gradual start up method.
88
do dry housings have PTO's?
no, wet housings do
89
Why do you need a scavenge system on a wet housing?
to prevent oil level from contacting outer circumference of converter= loss of power and heat
90
2 types of scavenging used on wet housings?
gravity (if converter housing above tranny)
pump (if converter housing and tranny are on same plane) driven by impeller
91
What does the torque divider combine?
single stage torque converter and a planetary gear set
92
how does a torque divider work?
splits varying percentages between converter and planetary (30% torque, 70%planetary)
93
functions of a torque divider?
provide auto clutching
multiply engine torque based on output shaft load
absorb power train shocks
94
in a torque divider, impeller connects to the:
and the turbine connects to the:
the planetary carrier connects to the:
sun gear
ring gear
output shaft
95
the difference of speed between the impeller (sung gear) and the turbine (ring gear) determines?
output shaft speed
96
on a torque divider, load or resistance on the output shaft determines the speed and direction of the?
turbine
97
power transmitted to the output shaft of the torque divider is controlled by ______ that affect the planetary gear set?
conditions
98
the amount of power applied to the input members will determine the speed and torque transmitted to the output shaft
T or F
True
99
What is happening in a torque divider when the engine is idling and output shaft stalled?
sun gear + impeller driven at engine speed, vortex flow not fast enough to make turbine + ring gear reactionary. the carrier is stalled, the planets act like reverse idlers. ring gear + turbine are idling in reverse direction bc of the sun gear.
100
what is happening in a torque divider when the engine is wide open throttle and output shaft speed stalled?
max engine torque multiplication. planet carrier gets max torque from sun gear but stays stationary. impeller at max speed. turbine rotates in reverse. lots of vortex flow
101
What type of housing does a torque divider have and where does that oil come from?
wet housing, comes from engine driven charge pump
102
2 types of mounting options for torque converters?
engine (integral) and remote
103
what does mounting the torque converter directly to the engine reduce?
the need to check proper torque converter/engine alignment
104
what torque converter gear design can be used to accommodate differences in misalignment between engine and torque converter?
rubber block tooth construction
105
since torque is transmitted through a fluid instead of a solid device, what vibrations are absorbed within the torque converter and are not passed on to the other powertrain components?
torsion vibrations
106
Benefit of remote mounting a torque converter?
better access to torque converter and transmission, don't need to disturb engine/engine mounts when removing converter/tranny
107
what is critical when installing or replacing a remote mounted torque converter?
proper driveline alignment
108
What is the first step when determining torque converter problems?
installing pressure and temp gauges at converter/tranny
109
where is the greatest amount of torque multiplication found?
when impeller is at greatest speed and turbine is stopped (stall condition)
110
What gear is the tranny in when performing a stall test?
the highest gear
111
what will happen if you perform a stall test in a low gear?
tranny/driveline damage from high amount of torque
112
what are 3 conditions that indicate a torque converter problem?
high stall speed
low stall speed
overheating
113
what does high stall speed indicate?
converter is not multiplying torque as required, or forward clutch in tranny is slipping
114
what does a slipping tranny clutch also cause?
high temp, look at temp when stall testing.
115
what does a low stall speed indicate?
engine not developing enough torque required, or a slipping stator overrunning clutch
116
what does overheating indicate?
operator is dumb and is in too high of a gear for the application
plugged converter oil cooler or fault charge pump
oil low from leakage
high oil level
117
what should you be aware of when removing a torque converter and tranny?
ensuring the torque converter doesn't fall off the tranny shaft
118
why should you check crankshaft end play after reinstalling a torque converter?
to ensure torque converter mounted properly, hasn't end loaded crankshaft
119
What are some other checks to make when reinstalling a torque converter?
flywheel housing bore diameter
flywheel housing bore eccentricity
flywheel housing face squareness
crankshaft hub eccentricity
crankshaft hub face squareness
flex plate flatness
converter axial location
crankshaft hub pilot diameter
shift linkages
120
when the output shaft on a torque divider is stalled and the engine is at max RPM the turbine is:
turning in reverse
