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11

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Factors Affecting Tightening Torque

The tightening torque is affected by

a wide varie ty of facto rs inc luding the

following. After tightening, always check

the torque with a torque wrench.

1) Voltage

When the battery pack becomes nearly

discharged, the voltage decreases and

the tightening torque drops.

Bolt Tightening Conditions

20
(
204
)
40
(
408
)
60
(
612
)
80
(
816
)
100
(
1020
)
120
(
1224
)
140
(
1428
)
165
(
1683
)
12 3
M12
M10
M14
M16
Tightening time (Sec.)M10, M12, M14, M16 Standard boltTightening torque
N • m
(kgf-cm)
M10
M8
M12
M14
20
(204)
40
(408)
60
(612)
80
(816)
100
(1020)
120
(1224)
140
(1428)
165
(1683)
12 3
Tightening time (Sec.)M8, M10, M12, M14 High tensile boltTightening torque
N • m
(kgf-cm)
Bolt
Nut
Washer
Steel plate
thickness 10 mm (3/8")
Washer
Spring washer

Tightening conditions

* The following bolts are used.

Standard bolts: Strength type 6.8

High tensile type 12.9

Explanation of the strength type
Bolt yield point
(80% of tensile strength)
48 kgf/mm2 (68000 psi)
Bolt tensile strength 60 kgf/mm2
(85000 psi)

2) Tightening time

Longer tightening time results in

increased tightening torque. Excessive

tightening, however, adds no value and

reduces the life of the tool.

3) Different bolt diameters

The size of the bolt diameter affects the

tightening torque.

Gene ral ly, as t he bolt diamet er

increases, tightening torque rises.

(EY7271 only)
(EY7271 only)
EY7270(EU).indb 11 2006/05/25 13:25:06