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General Information
General Information
When to Inspect the Clutch
The clutch should be inspected during the regularly scheduled
lubrication intervals as dictated in the Lubrication section or
when one of the following occur:
•
Clutch Free Pedal - If the clutch free pedal is one-
half of OEM specifications, not less than one-half
inch. During normal clutch use, the release bearing
will move toward the fork fingers and reduce “in
cab” free pedal.
•
Clutch Is Slipping - If the clutch is slipping, it may
require adjustment. If proper internal (clutch
adjuster) and external (clutch linkage) adjustment
has been made and the clutch still slips, it is likely
worn beyond its useful life and needs replacement.
Inspection for Clutch Life
If your vehicle is equipped with a Eaton Solo or Solo XL
(Extended Lube) Clutch, the clutch is equipped with a clutch
wear indicating tab that can be seen through the inspection
window. To calculate the expected life of a Solo, apply a paint
mark indicating the start point of the clutch wear indicating
tab. Record the mileage when this mark was made. After a few
months, reinspect the position of the clutch wear indicating
tab and record the new mileage. The difference between the
two readings can be used to estimate when the clutch will
need to be replaced.
For Example:
Starting Mileage = 10,000
After six (6) months mileage = 75,000
Clutch wear indicating tab movement = 0.625" (16 mm)
75,000-10,000 = 65,000 miles
65,000 miles/.625" = 104,000 miles per inch of tab movement
3.5" remaining tab movement
3.5" remaining tab movement X 104,000 miles per inch of tab
movement = 364,000 expected clutch life.
Designing a Clutch for a Specific
Application
There are three parts to designing a clutch for a specific appli-
cation. If the correct clutch is chosen, the truck will have good
engagement, protection for the driveline, long clutch life, and
minimal loss of torque.
1.
Check the Flywheel Bore (15.5" Clutch) - The fly-
wheel environment must be checked to make sure a
clutch can be used with it. The bore is important
when deciding what type of driven disc to use. The
bore must be large enough to allow for a proper fit of
the disc. See chart below.
2.
Torque Capacity - A clutch must be chosen that has
a torque capacity that is greater than or equal to the
peak torque of the engine. This is very important
today when an engine can be easily adjusted elec-
tronically to produce greater torque. There are two
factors in determining torque capacity. These two
factors are friction force and damper capacity.
•
Friction force is a product of the cover assem-
blies clamp load (also called plate load). This
factor was explained in the previous section,
and is stated as F(f) = uNPr. Determining the
friction force is important because if this force is
not greater than or equal to the peak torque of
the engine, the clutch will slip.
•
Damper capacity is what allows the clutch to
provide torsional protection for the entire drive-
line. If the peak engine torque exceeds this
capacity, the driveline will be abused. This abuse
will cause faster wear and possible destruction
of driveline components. Since damper capacity
is a product of the springs used in the damper,
changing the number and type of springs
changes the stiffness of the entire system.
3.
Application - Service replacement clutches should
have the same plate loads, damper and friction mate-
rial. Substituting from the original could shorten the
life of the clutch and drivetrain components.
# of Sp
r
i
n
gs Bo
r
e size
8-
S
p
r
i
n
g 7 1/4" (184.15mm)
10-
S
p
r
i
n
g 8 9/16" (217.48mm)
7-
S
p
r
i
n
g 9 3/4" (247.65mm)
9-
S
p
r
i
n
g* 9 3/4" (247.65mm)
*Mack/Volvo E
n
gi
n
e 2007 a
n
d
n
ewe
r
o
n
ly
Meas
ur
e
bo
r
e size
E
n
gi
n
e
Flywheel
