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Torque Specifications
Recommended fastener torque values are listed in the
following tables. For critical applications, as determined
by Toro, either the recommended torque or a torque that
is unique to the application is clearly identified and spe-
cified in this Service Manual.
These Torque Specifications for the installation and
tightening of fasteners shall apply to all fasteners which
do not have a specific requirement identified in this Ser-
vice Manual. The following factors shall be c onsidered
when applying torque: cleanliness of the fastener, use
of a thread sealant (e.g. Loctite), degree of lubrication
on the fastener, presence of a prevailing torque feature,
hardness of the surface underneath the fastener’s head
or similar condition which affects the installation.
As noted inthe following tables, torque values shouldbe
reduced by 25% for lubricated fasteners to achieve
the similar stress as a dry fastener. Torque values may
also have to be reduced when the fastener is threaded
into aluminum or brass. The specific torque value
should be determined based on the aluminum or brass
material strength, fastener size, length of thread en-
gagement, etc.
The standard method of verifying torque shall be per-
formed by marking a line on the fastener (head or nut)
and mating part, then back off fastener 1/4 of a turn.
Measure the torque required to tighten the fastener until
the lines match up.
Fastener Identification
Figure 1
Grade 1 Grade 5 Grade 8
Inch Series Bolts and Screws
Figure 2
Class 8.8 Class 10.9
Metric Bolts and Screws
Using a Torque Wrench with an Offset Wrench
Use of an offsetwrench(e.g.crowfootwrench)willaffect
torque wrench calibration due to the effective change of
torque wrench length. When using a torque wrench with
an offset wrench, multiply the listed torque recommen-
dation by the calculated torque conversion factor (Fig.
3) to determine proper tightening torque. Tightening
torque when using a torque wrench with an offset
wrench w ill be lower than the listed torque recommen-
dation.
Example: The measured effective length of the torque
wrench (distance from the center of the handle to the
center of the square drive) is 18”.
The measured effective length of the torque wrenchwith
the offset wrench installed ( distance from the center of
the handle to the center of the offset wrench) is 19”.
The calculated torque conversion factor for this torque
wrench with this offset wrench would be 18 / 19 = 0.947.
If the listed torque recommendation for a fastener is
from 76 to 94 ft--lb, the proper torque when using this
torque wrench with an offset wrench would be from 72
to 89 ft--lb.
Figure 3
(effective length of
torque wrench)
TORQUE CONVERSION FACTOR = A / B
A
B
(effective length of torque
Torque wrenchOffset wrench
wrench + offset wrench)
Product Records
and Maintenance