401Da: Transmission Fundamentals Flashcards
What are the three basic functions of a transmission?
- Multiply Torque
- Reverse
- Neutral
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If input torque is 1000ft/lbs and gear ratio is 2:1, what is the output torque?
2000ft/lb
What is the formula to find output speed if given the input speed and gear ratio?
Input Speed ÷ Gear Ratio = RPM
What are two primary considerations when selecting a transmission for a vehicle?
Horsepower and torque curves
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If a transmission has a 35% ratio step between gears, does it have a smaller or larger step between each gear as compared to a 20% ratio step?
Larger ratio step
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What is another name for the transmission input shaft?
Clutch shaft
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What are the other names for a transmission input shaft gear?
- Transmission drive gear
- Main drive gear
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Is neutral a gear position?
No
How many gear ratios does a transmission usually use at the same time?
2 gear ratios
Except direct drive
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What is used to control axial thrust on a transmission’s floating mainshaft gears?
Thrust washers with snap rings or lock pins
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What is the purpose of synchronizers in a transmission?
- Match the speed of the mainshaft gear with the mainshaft durring a shift
- Connect the selected mainshaft gear with the mainshaft
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What are three types of transmission synchronizers?
Block - Automotive use
Pin - Heavy duty use
Plate & Disc - On Mack trucks
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How are the inserts in the block type synchronizer hub held out?
Spring force
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What is the function of the insert in a block type synchronizer?
- Holds shift collar in centered position
- Allow blocker ring to line up the two gears, before joining together
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What are the 3 stages/phases of synchronizing?
- Braking/Energizing
- Synchronization
- Engagement
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What is used on some pin type synchronizers to provide spring-loaded resistance?
Split pins
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Is a shift lever generally a one or two piece design?
Two piece
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What is used in a shift lever to reduce transmission noise and vibration from entering the cab?
Isolator
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What would be the purpose of a spring-loaded plunger on the first/reverse shift block?
To ensure that the operator is making a conscious effort to select first or reverse.
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What is the purpose of an interlock?
To prevent operator from selecting more than one gear at the same time
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Where is an interlock pin located?
In the shift rails
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What is used in a transmission to help hold the shift rail in the selected position?
Detents
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What is an advantage of a multiple countershaft transmission?
- Bearings can be smaller & lighter
- Housing can be lighter
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By using a multiple countershaft transmission design, what type of gears can be used?
- Spur gears can be used
- Gears can be narrower
- No neeed for thrust washers
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Why were remote auxiliary transmissions a bad idea when they had shift linkages?
Susceptible to wear and damaged from falling objects
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Why is important to drain the air tanks daily on a truck with an air shift auxiliary transmission?
Air Filter Regulator is susceptible to clogging from mosture and rust
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What stops oil from leaking out of the transmission at the input shaft?
Windback seal on the input shaft
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On a multiple countershaft transmission, all the gears are the same size on the opposite shaft, except which ones?
PTO gears
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Where are the timing marks usually found on multiple counter shaft transmissions?
On the countershaft gears
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Multiple countershaft transmissions can use several housings. How are these housings kept in allignment?
a) shoulder bolts
b) precise doweling
c) tapered plugs
d) floating cap screws
b) precise dowelling
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The shift lever direclty moves the _______ in the shift bar housing.
a) shift fork
b) shift rail
c) sliding clutch
d) air valve shaft
b) shift rail
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In a 5 speed overdrive transmission, what gear would be direct?
a) first
b) reverse
c) fourth
d) fifth
c) fourth
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