• Simple - Only a spanner wrench required for installation
  • Safe - Ideal for applications where reliability is critical
  • Secure - Exceedingly high anti-loosening effect

How the Hard Lock Nut Works:

Figure 1 - Forcing a wedge into the gap between the cylinder and its surrounding tube makes it possible to create a powerfully locked assembly.

Figure 2 - Creating matching key grooves in both the nut and bolt, and then using a hammer to drive a wedge into those grooves does provide a powerful self-locking effect. However, this method is unsatisfactory from the standpoint of operability.

Figure 3 - The solution is to use two nuts to play the roles of the hammer and wedge respectively. A small eccentricity in the sliding part of the convex top of the lower nut acts as the wedge. When the concave upper nut is tightened, the effect produced is exactly the same as that produced by a hammer driving in a wedge. Moreover, it is much more effective to use a screw as this makes it very easy to force the wedge into place.

Hard Lock Nut Standard Dimensions (inch)

Hard Lock Nut Standard Dimensions (mm)


S H (lower nut) H1 (upper nut) B (width) C ℓ (total height) h Set/
Weight
Margin Coarse Fine Std. Dimen. Toler-ance Std. Dimen. Toler-ance Std. Dimen. Toler-ance Approx Approx Approx g
M6 1.0 - 5 0-0.48 5 0-0.48 10 0-0.6 11.5 8.3 3.3 3.3
M8 1.25 1.0 6.5 0-0.58 6.5 0-0.58 13 0-0.7 15 11 4.5 8.6
M10 1.5 1.25 8 // 8 // 17 // 19.6 13.5 5.5 17.6
M12 1.75 1.5 10 // 10 // 19 0-0.8 21.9 17 7.0 27.3
M14 2.0 1.5 11 0-0.7 11 0-0.7 22 // 25.4 18.5 7.5 39
M16 2.0 1.5 13 // 13 // 24 // 27.7 22.5 9.5 52.8
M18 2.5 1.5 15 // 15 // 27 // 31.2 25.5 10.5 80
M20 2.5 1.5 16 // 16 // 30 // 34.6 27.5 11.5 105
M22 2.5 1.5 18 // 18 // 32 0-1.0 37 31.5 13.5 130
M24 3.0 2.0 19 0-0.84 19 0-0.84 36 // 41.6 33 14 180
M27 3.0 2.0 22 0-1.84 22 0-1.84 41 // 47.3 38 16 246
M30 3.5 2.0 24 0-1.84 24 0-1.84 46 // 53.1 42 18 375
M33 3.5 2.0 26 0-1.84 26 0-1.84 50 // 57.7 46 20 480
M36 4.0 3.0 29 0-1.84 29 0-1.84 55 0-1.2 63.5 50 21 630
M39 4.0 3.0 31 0-2.0 31 0-2.0 60 & 69.3 54 23 935
M42 4.5 4.0 34 0-2.0 34 0-2.0 65 // 75 59 25 1080
M45 4.5 4.0 36 0-2.0 36 0-2.0 70 // 80.8 63 27 1330
M48 5.0 4.0 38 0-2.0 38 0-2.0 75 // 86.5 67 29 1595
M52 5.0 4.0 42 0-2.0 42 0-2.0 80 // 92.4 75 33 2055
M56 5.5 4.0 45 0-2.0 45 0-2.0 85 0-1.4 98.1 79 34 2410
M64 6.0 4.0 51 0-2.2 51 0-2.2 95 // 110 89 38 3172


Pdf Lower nut (tightening nut) Upper nut (locking nut)
Material classification: Tightening torque
standard reference value list (Unit: Nm) 		Materials are uniform
Class4 (SS400 or equivalent) Class8 (S45C or equivalent) Class10 (SCM435 or equivalent) A2,A4
(SUS304, 306 or equivalent) 		Tightening torque (Unit Nm)
4.8（320N／m㎡ 8.8（640N／m㎡ 10.9（900N／m㎡ 50（210N／m㎡） 70（450N／m㎡）
2.3～6 - - 1.5～4 3.3～9 4～5
5.6～15 11.2～30 15.8～42 3.7～10 7.9～21 9～13
11～30 22～59 31～84 7～20 16～42 18～24
19～52 39～104 55～146 13～34 27～73 27～39
31～82 62～165 87～232 20～54 44～116 40～58
48～129 97～257 136～362 32～84 68～181 70～100
66～177 133～354 187～498 44～116 93～249 100～150
94～251 188～502 265～706 62～165 132～353 120～200
128～341 256～683 360～960 84～224 180～480 150～250
163～434 325～868 458～1220 107～285 229～610 160～300
238～635 458～1269 669～1785 156～416 335～892 250～390
323～862 646～1723 909～2424 212～566 454～1212 270～440
440～1173 879～2345 1237～3298 289～770 618～1649 290～490
565～1506 1129～3012 1588～4235 371～988 794～2118 340～590
731～1949 1462～3898 2056～5481 480～1279 1028～2741 390～640
904～2411 1808～4821 2542～6780 593～1582 1271～3390 440～690
1128～3309 2257～6018 3174～8463 741～1975 1587～4231 490～740
1358～3620 2715～7240 3818～10181 891～2376 1909～5091 540～780
1755～4681 3510～9361 4937～13164 1152～3072 2468～6582 590～830
2183～5820 4365～11641 6139～16370 1432～3820 3069～8185 640～880
3288～8769 6577～17537 9248～24662 2158～5755 4624～12331 690～930


Thin Type Dimensions

Pdf S H (lower nut) H1 (upper nut) B (width) C ℓ (total height) h Uper nut tight. torque SS400
Nm)
Margin Coarse Std. Dimen. Tolerance Std. Dimen. Tolerance Std. Dimen. Tolerance Approx Approx Approx
M16 2.0 10 0-0.58 10 0-0.58 24 0 -0.8 27.7 16.5 6.5 70～100
M18 2.5 11 0-0.7 11 0-0.7 27 // 31.2 17.5 6.2 100～150
M20 2.5 12 // 12 // 30 // 34.6 19.5 7.5 120～200
M22 2.5 13 // 13 // 32 0-1.0 37 21.5 8.5 150～250
M24 3.0 14 // 14 // 36 // 41.6 23 9.0 160～300
M27 3.0 16 // 16 // 41 // 47.3 26 10 250～390
M30 3.5 18 // 18 // 46 // 53.1 30 12 270～440
M33 3.5 20 0-0.84 20 0-0.84 50 // 57.7 34 13 290～490
M36 4.0 21 // 21 // 55 0-1.2 63.5 34 13 340～590
M39 4.0 23 // 23 // 60 // 69.3 38 14 390～640
M42 4.5 25 // 25 // 65 // 75 40 15 440～690
M45 4.5 27 // 27 // 70 // 80.8 45 18 490～740
M48 5.0 29 // 29 // 75 // 86.5 49 20 540～780
M52 5.0 31 0-1.0 31 0-1.0 80 // 92.4 53 22 590～830
M56 5.5 34 // 34 // 85 0-1.4 98.1 57 23 640～880
M64 6.0 38 // 38 // 95 // 110 63 25 690～930


*This product's lower nut tightening torque is approx. 60 ~ 80% of that of the «H-1» lower nut.
Semi Thin Type Dimensions

Pdf S H (lower nut) H1 (upper nut) B (width) C ℓ (total height) h Uper nut tight. torque SS400
Nm)
Margin Coarse Std. Dimen. Tolerance Std. Dimen. Tolerance Std. Dimen. Tolerance Approx Approx Approx
M16 2.0 13 0-0.7 10 0-0.58 24 0 -0.8 27.7 19.5 9.5 70～100
M18 2.5 15 0-0.7 11 0-0.7 27 // 31.2 21.5 10.5 100～150
M20 2.5 16 // 12 // 30 // 34.6 23.5 11.5 120～200
M22 2.5 18 // 13 // 32 0-1.0 37 26.5 13.5 150～250
M24 3.0 19 0-0.84 14 // 36 // 41.6 28 14 160～300
M27 3.0 22 // 16 // 41 // 47.3 32 16 250～390
M30 3.5 24 // 18 // 46 // 53.1 36 18 270～440
M33 3.5 26 // 20 0-0.84 50 // 57.7 40 20 290～490
M36 4.0 29 // 21 // 55 0-1.2 63.5 46 21 340～590
M39 4.0 31 0-1.0 23 // 60 // 69.3 46 23 390～640
M42 4.5 34 // 25 // 65 // 75 50 25 440～690
M45 4.5 36 // 27 // 70 // 80.8 54 27 490～740
M48 5.0 38 // 29 // 75 // 86.5 58 29 540～780
M52 5.0 42 // 31 0-1.0 80 // 92.4 64 33 590～830
M56 5.5 45 // 34 // 85 0-1.4 98.1 68 34 640～880
M64 6.0 51 0-1.2 38 // 95 // 110 78 38 690～930


Pdf d s e m & m1 L Unit Weight
Normal Size or Basic Major Dia. of Thread Width Across Flats Width Across Corners Thickness Hex Nuts Overall Height
Basic Max. Min. Max. Min. Basic Max. Min. Approx. Approx.
UNC 1/4 0.2500 7/16 0.438 0.428 0.505 0.488 7/32 0.226 0.212 0.370 3.3
UNC 5/16 0.3125 1/2 0.500 0.489 0.577 0.557 17/64 0.273 0.258 0.433 7.9
UNC 3/8 0.3750 9/16 0.562 0.551 0.650 0.628 21/64 0.337 0.320 0.535 17.6
UNC 7/16 0.4375 11/16 0.688 0.675 0.794 0.768 3/8 0.385 0.365 0.610 20.8
UNC 1/2 0.5000 3/4 0.750 0.736 0.866 0.840 7/16 0.448 0.427 0.724 28.1
UNC 5/8 0.6250 15/16 0.938 0.922 1.083 1.051 35/64 0.559 0.515 0.937 52.8
UNC 3/4 0.7500 1-1/8 1.125 1.088 1.299 1.240 41/64 0.665 0.597 1.106 105.0
UNC 7/8 0.8750 1-5/16 1.312 1.269 1.516 1.447 3/4 0.776 0.704 1.307 130.0
UNC 1 1.0000 1-1/2 1.500 1.450 1.732 1.653 55/64 0.887 0.811 1.500 246


Tightening Torque

Pdf Size Concave Nut
UNC 1/4 4 - 5 N•m
UNC 5/16 9 -13 N•m
UNC 3/8 18 - 24 N•m
UNC 7/16 27 - 39 N•m
UNC 1/2 40 - 58 N•m
UNC 5/8 70 - 100 N•m
UNC 3/4 120 - 150 N•m
UNC 7/8 150 - 250 N•m
UNC 1 250 - 390 N•m


*This product's lower nut tightening torque is the same as that of the«H-1» lower nut.