Published 08/16/19 Control # 112-05 1-9
500E2 SERVICE MANUAL INTRODUCTION
National Crane
Table 1-1 Inch Series with Coarse Threads (UNC) – Zinc Flake Coated
Nominal Size, Threads per
Inch, and Series
Designation
Grade
Torque (ft/lb)
Maximum Nominal Minimum
1/4-20 UNC
5 6.6 6.4 6.2
8 9.3 9.0 8.8
5/16-18 UNC
5 13.5 13.2 12.8
8 19.1 18.6 18.1
3/8-16 UNC
5 24.0 23.4 22.8
8 33.9 33.1 32.2
7/16-14 UNC
5 38.4 37.4 36.5
8 54.3 52.9 51.5
1/2-13 UNC
5 58.6 57.1 55.7
8 82.8 80.7 78.6
9/16-12 UNC
5 84.5 82.4 80.3
8 119.4 116.5 113.5
5/8-11 UNC
5 116.6 113.7 110.8
8 164.8 160.7 156.6
3/4-10 UNC
5 206.8 201.7 196.5
8 292.3 284.9 277.6
7/8-9 UNC
5 333.8 325.4 317.1
8 471.6 459.8 448.0
1-8 UNC
5 500.3 487.8 475.3
8 707.0 689.3 671.6
1 1/8-7 UNC
5 624.0 608.4 592.8
8 1001.4 976.4 951.4
1 1/4-7 UNC
5 880.5 858.5 836.5
8 1413.1 1377.8 1342.5
1 3/8-6 UNC
5 1154.5 1125.6 1096.7
8 1852.8 1806.5 1760.2
1 1/2-6 UNC
5 1532.0 1493.7 1455.4
8 2458.8 2397.3 2335.8
Table 1-2 Inch Series with Fine Threads (UNF) – Zinc Flake Coated
Nominal Size, Threads per
Inch, and Series
Designation
Grade
Torque (ft/lb)
Maximum Nominal Minimum
1/4-28 UNF
5 7.5 7.3 7.1
8 10.6 10.4 10.1