Komatsu D31EX-21, Operation & Maintenance Manual, Page: 195 / 256

MAINTENANCE
STANDARD TIGHTENING TORQUES FOR BOLTS AND NUTS
4-15
STANDARD TIGHTENING TORQUES FOR BOLTS AND
NUTS 4
TORQUE LIST 4
CAUTION
If nuts, bolts, or other parts are not tightened to the specified torque, it will cause looseness or damage to
the tightened parts, and this will cause failure of the machine or problems with operation.
Always pay careful attention when tightening parts.
Unless otherwise specified, tighten the metric nuts and bolts to the torque shown in the table below.
If it is necessary to replace any nut or bolt, always use a Komatsu genuine part of the same size as the part that
was replaced.
Apply the following table for Hydraulic Hose.
Thread
diameter of
bolt
(a)(mm)
Width
across flats
(b)(mm)
Tightening torque
Target value Service limit
N·m kgf·m N·m kgf·m
6
8
10
12
14
10
13
17
19
22 13.2
31
66
113
172
1.35
3.2
6.7
11.5
17.5
11.8-14.7
27-34
59-74
98-123
153-190
1.2-1.5
2.8-3.5
6.0-7.5
10.0-12.5
15.5-19.5
16
18
20
22
24 24
27
30
32
36 260
360
510
688
883 26.5
37
52.3
70.3
90
235-285
320-400
455-565
610-765
785-980 23.5-29.5
33.0-41.0
46.5-58.0
62.5-78.0
80.0-100.0
27
30
33
36
39 41
46
50
55
60 1295
1720
2210
2750
3280 132.5
175.0
225.0
280.0
335.0 1150-1440
1520-1910
1960-2450
2450-3040
2890-3630 118.0-147.0
155.0-195.0
200.0-250.0
250.0-310.0
295.0-370.0
Nominal - No. of
threads (a)
Width
across
flats (b)
(mm)
Tightening torque
Target value Permissible range
N·m kgf·m N·m kgf·m
9/16 -18UNF 19 44 4.5 35 - 63 3.5 - 6.5
11/16 -16UN 22 74 7.5 54° 93 5.5° 9.5
13/16 -16UN 27 103 10.5 84° 132 8.5° 13.5
1 -14UNS 32 157 16.0 128° 186 13.0° 19.0
13/16 -12UN 36 216 22.0 177° 245 18.0° 25.0