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MAINTENANCE
STANDARD TIGHTENING TORQUES FOR BOLTS AND NUTS
STANDARD TIGHTENING TORQUES FOR BOLTS AND NUTS
TORQUE LIST
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.
Thread
diameter
of bolt
(a)(mm)
Width
across
flats
(b)(mm)
Tightening torque
Target value Service limit
N
·
mkgf
·
mlbft N
·
mkgf
·
mlbft
6
8
10
12
14
10
13
17
19
22
13.2
31
66
113
177
1.35
3.2
6.7
11.5
18
9.8
23.1
48.5
83.2
130.2
11.8-14.7
27-34
59-74
98-123
157-196
1.2-1.5
2.8-3.5
6.0-7.5
10.0-12.5
16.0-20.0
8.7-10.8
20.3-25.3
43.4-54.2
72.3-90.4
115.7-144.7
16
18
20
22
24
24
27
30
32
36
279
382
549
745
927
28.5
39
56
76
94.5
206.1
282.1
405.0
549.7
683.5
245-309
343-425
490-608
662-829
824-1030
25.0-31.5
35.0-43.5
50.0-62.0
67.5-84.5
84.0-105.0
180.8-227.8
253.2-314.6
361.7-448.4
488.2-611.2
607.6-759.5
27
30
33
36
39
41
46
50
55
60
1320
1720
2210
2750
3280
135.0
175.0
225.0
280.0
335.0
976.5
1265.8
1627.4
2025.2
2423.1
1180-1470
1520-1910
1960-2450
2450-3040
2890-3630
120.0-150.0
155.0-195.0
200.0-250.0
250.0-310.0
295.0-370.0
868.0-1085.0
1121.1-1410.4
1446.6-1808.3
1808.3-2242.2
2133.7-2676.2
Apply the following table for Hydraulic Hose.
Thread
diameter
a (mm)
Width
across
flats
b (mm)
Tightening torque
Target value Permissible range
N
·
mkgf
·
mlbft N
·
mkgf
·
mlbft
10 14 14.7 1.5 10.8 12.7 - 16.7 1.3 - 1.7 9.4 - 12.3
14 19 29.4 3.0 21.7 27.5 - 39.2 2.8 - 4.0 20.3 - 28.9
18 24 78.5 8.0 57.9 58.8 - 98.1 6.0 - 10.0 43.4 - 72.3
22 27 117.7 12.0 86.6 88.3 - 137.3 9.0 - 14.0 65.1 - 101.3
24 32 147.1 15.0 108.5 117.7 - 176.5 12.0 - 18.0 86.8 - 130.2
30 36 215.7 22.0 159.1 176.5 - 245.2 18.0 - 25.0 130.2 - 180.8
33 41 255.0 26.0 188.1 215.7 - 284.4 22.0 - 29.0 159.1 - 209.8
4 - 16
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