MAINTENANCE
TIGHTENING TORQUE SPECIFICATIONS
TIGHTENING TORQUE SPECIFICATIONS TIGHTENING 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. The tightening torque is determined by the width across the flats of the nut and bolt. 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. Tightening torque Thread diameter a (mm)
Width across flat b(mm)
N•m
kgf•m
N•m
kgf•m
6
10
13.2
1.35
11.8 – 14.7
1.2 – 1.5
Target value
Service limit
8
13
31
3.2
27 – 34
2.8 – 3.5
10
17
66
6.7
59 – 74
6.0 – 7.5
12
19
11
11.5
98 – 123
10.0 – 12.5
14
22
177
18
157 – 196
16.0 – 20.0
16
24
279
28.5
245 – 309
25.0 – 31.5
18
27
382
39
343 – 425
35.0 – 43.5
20
30
549
56
490 – 608
50.0 – 62.0
22
32
745
76
662 – 829
67.5 – 84.5
24
36
927
94.5
824 – 1030
84.0 – 105.0
27
41
1320
135.0
1180 – 1470
120.0 – 150.0
30
46
1720
175.0
1520 – 1910
155.0 – 195.0
33
50
2210
225.0
1960 – 2450
200.0 – 250.0
36
55
2750
280.0
2450 – 3040
250.0 – 310.0
39
60
3280
335.0
2890 – 3630
295.0 – 370.0
42
65
3830
390.0
3430 – 4220
350.0 – 430.0
45
70
4650
475.0
4413 – 4903
450.0 – 500.0
48
75
1960 N•m {200 kgf•m} (1446.6 lbft) + Additional tightening angle
Apply the following table for Hydraulic Hose. Tightening torque
Nominal No. of threads (a) (mm)
Width across flat b (mm)
N•m
kgf•m
N•m
kgf•m
10
14
14.7
1.5
12.7 – 16.7
1.3 – 1.7
14
19
29.4
3.0
27.5 – 39.2
2.8 – 4.0
18
24
78.5
8.0
58.8 – 98.1
6.0 – 10.0
22
27
117.7
12.0
88.3 – 137.3
9.0 – 14.0
24
32
147.1
15.0
117.7 – 176.5
12.0 – 18.0
30
36
215.7
22.0
176.5 – 245.2
18.0 – 25.0
33
41
255.0
26.0
215.7 – 284.4
22.0 – 29.0
4-14
Target value
Permissible range
