HET 4 CLUTCH 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 held 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
True or False
In a spring-loaded clutch, when engaged two out of three components rotate together at the same speed?
FALSE all three components rotate together at the same speed
Pressure plate, clutch disc, flywheel friction surface
What dictates a clutch is a PUSH or PULL type?
The direction the release bearing is going
Pull-type clutches are used on what level of vehicles?
medium to heavy duty
The release bearing pushes or pulls on what part of the component?
Release levers
When the clutch disc is disengaged what moves together?
Clutch cover/pressure plate assembly rotates with the flywheel
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
Spring strength comes from what?
Its compression
When a spring has to travel further what happens to its pressure application ability?
it gets weaker
When adjusting clutch’s lever pivot point what are we adjusting?
The spring force available
Does free play become more or less when the clutch is worn severely?
Less free play
In medium - heavy duty truck, what is the common clutch type?
Pull type
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
Where is a flywheel mounted to making it run at engine speeds?
Crankshaft flange
What are two types of flywheels?
Flat and Countersunk
How many reservoirs does a hydraulic clutch master cylinder have?
ONE
If a hydraulic clutch actuation mechanism fails, what is the complaint?
Clutch will not disengage
What type of air is used in a air over hydraulic assist for clutch use?
compressed air
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 over Hydraulic
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
Flat flywheels are used on a single or a double disc clutch assembly?
Both
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
What law is followed in hydraulics?
Pascall’s law
Do perpendicular spring clutches have helper springs?
NO
What spring clutch has helper springs?
Angle springs
In an air over hydraulic clutch mechanism, where do the clutch master cylinder send pressurized fluid to when the pedal is pushed on?
To the integral hydraulic cylinder
What is the air chamber’s default position in an air over hydraulic clutch mechanism?
Exhaust to atmospher
List the controlled and assist pressures in an air over hydraulic clutch mechanism?
Hydraulic - Control
Air - Assist
True or False
If clutch discs are the same size they can handle the same torque loads?
False, diameter is not the only thing that matters when rating a clutch disc
Do flywheels need to be measured for thickness and true rotation when replacing the clutch or troubleshooting a clutch fault?
Yes, its a wearable component
What drives the intermediate plate in a system with a countersunk flywheel system?
Flywheel
What is the point of an intermediate plate?
Additional friction surface
Clutch covers are usually made from?
Cast iron
or
Stamped steel
Which is better for heavy duty applications, cast iron clutch covers or stamped steel?
Cast iron is heavier and can absorb more heat
Why can a clutch design with 2 clutch discs handle more torque?
Larger surface area (double)
What are two PROs to stamped steel clutch covers?
Higher engine speeds and Lighter
Anything directly coupled to the flywheel/crank are considered what kind of member?
Driven or Drive
Drive
Anything directly coupled to the transmission is considered what kind of member?
Driven or Drive
Driven
Rigid clutch discs how is the lining connected to it?
Bonded or riveted
Where are rigid clutches used? What type of application?
Where there is a limit amount of engagement and disengagement occur
Dampened clutch discs are considered flexible or rigid?
Flexible
What is used on a dampened clutch disc to absorb torsional shock loads?
spring-loaded, limited-movement mechanism
What do dampened clutch discs do to 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
Organic clutch linings in CANADA are made with asbestos?
No, asbestos is not legal in Canada
BUT it can be used when manufactured in another country
In an NAO clutch disc lining what could be added to the material?
binders, resins, fillers, metallic particles
Is it more likely for a ceramic clutch disc lining to last longer than a organic clutch disc lining?
Yes