401A: Clutch Fundamentals and Service Flashcards
190401A CLUTCH
Spring loaded clutches have three styles of spring, what are they?
Perpendicular, diaphragm and angle
What are the two types of spring clutches?
Push and Pull type
When the operator pushes the clutch pedal to the floorboard, is the clutch engaged or disengaged?
Disengaged
The springs in the clutch are naturally in the engage or disengaged position?
Engaged
Where are the pressure springs usually located?
Between the clutch cover and pressure plate
When a spring-loaded clutch is engaged what happens to the clutch disc, pressure plate and flywheel friction surface?
The clutch disc is held tightly between the pressure plate and flywheel friction surfaces
What dictates a clutch as a PUSH or PULL type?
The direction the release bearing is moved to release the clutch
Heavy duty vehicles use what type of clutch?
Pull type
The release bearing pushes or pulls on what component within the clutch?
Release levers
When the clutch disc is disengaged what moves together?
Clutch cover/pressure plate assembly rotates with the flywheel
Clutch discs rotates with the transmission input shaft
When a clutch is getting ridden a lot what will wear?
a) flywheel
b) clutch disc
c) friction material
d) pressure plate
c) The clutch friction material - lining
When a spring has to travel further what happens to its pressure application ability?
it gets weaker
Does clutch pedal free play become more or less when the clutch is worn severely?
Less free play
What are two things that dictate if the clutch is a push or pull type?
Release bearing travel and release levers travel
What are the four ways to find the size of a clutch?
- Diameter of the disc
- Outside diameter of the clutch shaft
- Number of splines in the hub
- Number of dampening springs
What are two types of flywheels?
Flat and Countersunk
When an operator releases the pedal, what position is the clutch in?
Engaged
What are the actuation mechanisms used for clutches?
- Mechanical linkage
- Hydraulic
- Air
In a vehicle where the transmission/engine are VERY far from the operator pedal, what actuation mechanism is used?
Hydraulic
or
Air over Hydraulic
If the engine/transmission is close to the operators clutch pedal, what actuation mechanism is most likely to be used?
Mechanical Linkage
If a clutch pedal linked to a mechanical linkage has lots of free play but the clutch is adjusted correctly, what is cause?
The bearings, rod end and/or bushings in the linkage are worn
Out of the three clutch actuation mechanisms, which is the least expensive?
Mechanical linkage
If there are air bubbles in the hydraulic clutch system, what is the operators complaint?
Spongy pedal
If a clutch pedal has excessive side to side movement, what should a tech be looking for as the cause?
Worn bushings in the pedal linkage
What are basic inspections on a hydraulic clutch that a technician can do?
Check lines for damage and wear
Check for leaks
Pedal movement/feel
Reservoir level and fluid condition
When installing a new master cylinder in a hydraulic clutch assembly what should be done FIRST?
Bench bleed the master cylinder
A rod end link is considered failed when what movement is felt?
The ball can move separately from the socket
In an air over hydraulic clutch mechanism, which one is used for the control and which one is used as the assist?
Hydraulic - Control
Air - Assist
What drives the intermediate plate in a system with a countersunk flywheel system?
Flywheel
What is the purpose of an intermediate plate?
Additional friction surface when using multiple friction discs
Where are rigid clutches used? What type of application?
Where there is a limited amount of engagement and disengagement
Are dampened clutch discs considered flexible or rigid?
Flexible
What is used on a dampened clutch disc to absorb torsional shock loads?
A spring-loaded, limited-movement mechanism
What do dampened clutch discs do to the service life of the clutch?
Extend clutch service life
What are the two types of clutch disc linings materials?
Organic and Ceramic
What clutch disc lining should be used where high heat will be encountered?
Ceramic
An intermediate plate is used when?
Two clutch discs are used
What component helps stop intermediate plate vibrations and reduce noise?
Anti-rattle springs
How is the intermediate plate coupled to the clutch cover?
Drive Straps
Drive Slots
A clutch that sounds like it is “rattling” when engaged could be a result of?
A broken dampening springs in the clutch disc
A clutch is starting to feel like its causing hard shifts, what could be the cause?
Broken dampening springs in the clutch disc
How much gap should there be between the yoke and release bearing?
1/8”
Operator complains the clutch is feeling stiff or harder, what could be the cause?
Worn clutch disc
What generally causes premature failures of transmissions and clutches?
Abuse from operator
What can cause a failure of a self-adjuster in the clutch?
Contamination - tiny teeth
Which type of clutch can have an internal threaded ring that you must unlock first before adjusting the clutch?
Pull-type, manualy adjusted clutch
When does a clutch brake activate?
When the clutch pedal is fully depressed.
When the operator is shifting from neutral to first or reverse gear
What does a clutch brake prevent?
Gear teeth clash during gear selection
What is the purpose of the clutch brake?
To stop rotation of the transmission input shaft
True or False
The release bearing pushes up against the clutch brake when the clutch is disengaged.
True
At what point in clutch pedal travel should the clutch brake activate?
1/2”-1” from the floor (bottom of travel)
What can cause premature failure of the clutch brake?
contamination, improper use
Operator complains the truck is hard to get into 1st gear and reverse gear, what could be the cause?
Failed clutch brake
What is considered improper use of the clutch brake?
Engaging the clutch brake while traveling in 2-6th gear
If a clutch brake is able to slip, what will happen to service life of the component?
service life will be extended
What will prolong clutch service life?
regular inspection, adjustment, keep clean
Lubrication contamination of the clutch lining could give what symptom?
Chatteringing during engagement and disengagement
A glazed clutch disc that is worn in an unusual pattern could be caused by?
Lubrication contamination
What should be used when moving the heavy clutch assembly away from the engine?
Two Long Guide Studs
What should be used to help control the clutch discs while the clutch is installed?
Clutch disc aligning tool
What must be done before setting the clutch free pedal?
Check all of the external linkage for wear and signs of binding, must be properly lubricated
To check the flywheel bore runout, what position does the dial-indicator need to be in?
90° to the surface
Why should you check crankshaft end play more than once?
To squeeze out oil film, giving a more accurate reading
What should never be used to clean clutch components?
Grease, oil based products, varsol
An operator complains the clutch feels like it is dragging/grabbing. What could be the cause?
Flywheel face runout is beyond specs
What two forces do centrifugal clutches utilize?
Centrifugal force
Friction Force
What could cause a centrifugal force clutch to stay engaged?
Release/return springs have failed
Which component is spring controlled in a centrifugal force clutch?
Friction shoes
In what applications would a rigid clutch disc be used?
Where limited amount of engagement and disengagement occur
Push type clutches are usually used on what class of vehicle?
light-medium duty
What causes the MOST wear to a clutch friction disc?
Clutch slippage
The springs inside a clutch friction disc are called what?
Torsion Dampening springs
What are the two design types of clutch covers?
Cast Iron:
-Heavy duty use
Stamped Steel:
-High speed & light duty use
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What are the advantages of cast iron clutch covers?
Handles high heat and high torque loads
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What are advantages of the stamped steel clutch covers?
Lighter design and allow for higher engine speeds
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