Fuji Bearing Lock Nuts
Quality, Secure Bearing Locking Nut Solutions
Fuji bearing lock nuts are designed for high-performance shaft fastening and accurate bearing positioning. Unlike conventional locking systems that require machined keyways, tab washers or additional components, the one-piece Fuji locknut provides a compact and reliable solution for securing bearings directly onto shafts.
Each bearing locking nut features a spring-peened friction ring that generates controlled prevailing torque, ensuring secure bearing retention and precise axial positioning of bearings, gears or pulleys. This self-locking design improves shaft balance, reduces vibration and delivers long-term fastening reliability in rotating assemblies.
Manufactured in carbon steel, high-carbon steel and stainless steel, Fuji bearing locknuts are precision-machined with ISO metric threads and available in sizes M10 to M150, with IEC stocking M10 to M100 as standard. Installation tools are available up to M50 for efficient fitting and maintenance.
These lock nuts for bearings are widely used across industrial machinery, automotive manufacturing, power generation, material handling and machine tool assemblies, as well as defence and aerospace applications where secure retention under dynamic loads is critical. By eliminating keyways and multi-component locking systems, they help improve assembly efficiency and maintain shaft integrity in high-speed equipment.
For full technical specifications and sizing information, see the full Fuji Locknuts Catalogue.
- Slim design & simplified bearing installation – no keyway machining or tab washers required
- Re-usable, self-locking action – retains prevailing torque for up to 100 installs
- Wide size range for shaft retention – standard M10 to M150, tools available up to M50
- Improved shaft balance & integrity – reduces vibration, shock, and rotational imbalance in rotating machinery
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Fuji Bearing Locknuts Catalogue
FUJI BEARING LOCKNUTS
The Fuji Fine-U-Nut was developed to simplify the assembly and reduce costs involved in securing ball bearings.
The manufacturer has more than 30 years experience in locknut technology and their factory is ISO 9001 approved.
Construction & Function
The Fuji Bearing Locknut is a one piece item where the locking function is performed by a spring peened into the top of the nut. In use the spring bears on the flank of the shaft thread with force (P) generating reaction force (P’) in the screw threads with a resulting high friction torque (prevailing torque). The nut therefore remains locked in position.
Fuji Bearing Locknuts are manufactured in carbon, high carbon and stainless steel and are a stock item at IEC in sizes from M10 to M100.
KEY BENEFITS
- Unique slim body design
- Secure locking without keyway and tab washer
- Improved shaft strength and balance
- Simple infinite adjustment
- Re-usable up to 100 times
- Sizes from M10 to M150
- Carbon, high carbon and stainless steel versions
- Resists vibration and shock
- Equally effective for rotation in either direction even with rapid reversals
- One piece construction reduces stock and allows simpler, quicker assembly
PROOF LOAD & MAXIMUM TIGHTENING TORQUE
| Part No | SS (Low Carbon Steel) | SC (High Carbon Steel) | SUS (Stainless Steel) | ||||
| Prevailing Torque (Nm) | Proof Load (N) | Max Tightening Torque (Nm) | Proof Load (N) | Max Tightening Torque (Nm) | Proof Load (N) | Max Tightening Torque (Nm) | |
| FU00 | 1.4 | 9500 | 13.3 | 12860 | 17.6 | 7710 | 8.9 |
| FU01 | 2.2 | 11080 | 18.9 | 15000 | 24.8 | 9000 | 12.7 |
| FU02 | 3.1 | 17810 | 36.7 | 24120 | 48.6 | 14470 | 24.3 |
| FU03 | 3.7 | 20180 | 46.9 | 27330 | 62.2 | 16400 | 31.0 |
| FU04 | 4.7 | 29020 | 77.8 | 39300 | 103.7 | 23580 | 50.9 |
| FU05 | 9.8 | 41160 | 139.4 | 55740 | 185.3 | 33440 | 91.7 |
| FU06 | 12.7 | 49400 | 199.4 | 66890 | 265.5 | 40130 | 130.6 |
| FU07 | 16.2 | 66500 | 309.4 | 90050 | 413.3 | 54030 | 201.5 |
| FU08 | 19.6 | 87080 | 458.4 | 117920 | 613.9 | 70750 | 296.9 |
| FU09 | 23.5 | 109720 | 645.6 | 148580 | 865.9 | 89150 | 416.6 |
| FU10 | 29.4 | 134580 | 877.2 | 182250 | 1177.5 | 109350 | 565.2 |
| FU11 | 35.3 | 145140 | 1041.1 | 196540 | 1397.3 | 117920 | 670.8 |
| FU12 | 41.2 | 158330 | 1238.1 | 214410 | 1662.1 | 128640 | 797.6 |
| FU13 | 50.0 | 188680 | 1595.2 | 255500 | 2142.5 | 153300 | 1026.5 |
| FU14 | 54.9 | 203190 | 1847.0 | 275160 | 2481.8 | 165090 | 1187.4 |
| FU15 | 66.6 | 237500 | 2310.9 | 321620 | 3105.9 | 192970 | 1484.9 |
| FU16 | 70.6 | 295560 | 3049.8 | 400230 | 4104.9 | 240140 | 1953.2 |
| FU17 | 76.4 | 336460 | 3679.8 | 455620 | 4956.0 | 273370 | 2353.5 |
| FU18 | 83.3 | 356250 | 4123.1 | 482430 | 5554.0 | 289450 | 2636.2 |
| FU19 | 88.2 | 401110 | 4889.4 | 543180 | 6590.0 | 325900 | 3122.3 |
| FU20 | 96.0 | 448610 | 5748.4 | 607500 | 7750.5 | 364500 | 3668.1 |
SOCKET TOOLS FOR BEARING LOCKNUTS
Sizes available up to M50.
Quotations/dimensions for larger sockets can be supplied on request.
| Order Ref | Nut | D | L | h1 | h2 | s |
| FU00 | M10x0.75 | 23 | 36 | 4.4 | 24 | 9.52 (3.8″) |
| FU01 | M12x1.0 | 27 | 37 | 4.6 | 25 | |
| FU02 | M15x1.0 | 31 | 38 | 5.7 | 26 | |
| FU03 | M17x1.0 | 34 | 39 | 5.8 | 27 | |
| FU04 | M20x1.0 | 38.5 | 40 | 6.9 | 28 | |
| FU05 | M25x1.5 | 45.5 | 46.5 | 8.1 | 30.5 | 12.7 (1/2″) |
| FU06 | M30x1.5 | 53 | 50 | 8.1 | 34 | |
| FU07 | M35x1.5 | 60.5 | 53.5 | 9.2 | 37.5 | |
| FU08 | M40x1.5 | 67 | 57 | 10.2 | 41 | |
| FU09 | M45x1.5 | 74.5 | 60.5 | 11.2 | 44.5 | |
| FU10 | M50x1.5 | 80 | 64 | 12.2 | 48 |
AXIAL IMPACT VIBRATION TEST
| Sample size | M20 x 1.0 |
| Frequency | 21Hz |
| Excitation stroke | 11mm |
| Impact stroke | 10mm |
| Vibrating acceleration of excitation table | 10G |
| Test time | 60 minutes |
| Direction of impact | Bolt axis direction |
| Clamping torque | 53.9N.m (550kgf.cm) |
| Sample Nut | Excitation Time (Minutes) 10 20 30 40 50 60 | Test Results | |
| Standard bearing nut with tongued washer | Looseness
|
Nut came off | |
| FUJI Locknut |
|
No effect |
Fuji Locknuts Rotational Life Test
| Sample size | M55 x 2.0 | |
| Speed of revolution | 2,300rpm | |
| Testing cycles | One cycle (forward rotation, stop, reverse rotation, stop): 10 seconds | |
| Stopping time | One forward rotation: 0.30 seconds. For reverse rotation: 0.27 seconds |
| Internal force applied to the nut during stopping | ||
| Sample Nut | Inertial Force : N.m (kgf.cm) | |
| For forward rotation | For reverse rotation | |
| Standard Bearing Nut | 0.14 (1.42) | 0.15 (1.57) |
| FUJI Locknut | 0.15 (1.52) | 0.17 (1.69) |
| RESULTS | ||
| Sample Nut | Sample No | Result on endurance text |
| Standard Bearing Nut & Washer | 1 | Washer damaged & nut came off at approx. 110,000 cycles |
| 2 | Washer damaged & nut came off at approx. 330,000 cycles | |
| FUJI Locknut | 3 | No change after 500,000 cycles |
| 4 | ||
| External view of testing machine | External view of damaged & detached washers (sample No 2) |
BEARING LOCKNUT DIMENSION TABLE
| SC Series | SS Series | SUS Series | Designation of Thread D1 | D3 | D4 | g | T | S | h | H | Perpend-icularity of Bearing Surface | |||||
| FU00SC | FU00SS | FU00SUS | M10x0.75 | 18 | 0-0.5 | 13.5 | 0-0.5 | 14.4 | 0-0.5 | 1.8 | 3 | +0.2 | 4 | 5.2 | +0.3 | 0.05 |
| FU01SC | FU01SS | FU01SUS | M12x1.0 | 22 | 17 | 18.4 | 1.8 | 3 | 4 | 5.4 | ||||||
| FU02SC | FU02SS | FU02SUS | M15x1.0 | 25 | 21 | 21.4 | 1.8 | 4 | 5 | 6.5 | +0.5 | |||||
| FU03SC | FU03SS | FU03SUS | M17x1.0 | 28 | 24 | 24.2 | 1.9 | 4 | 5 | 6.4 | ||||||
| FU04SC | FU04SS | FU04SUS | M20x1.0 | 32 | 26 | 28.4 | 1.8 | 4 | 6 | 7.7 | ||||||
| FU05SC | FU05SS | FU05SUS | M25x1.5 | 38 | 32 | 34 | 2.0 | 5 | 7 | 9.1 | ||||||
| FU06SC | FU06SS | FU06SUS | M30x1.5 | 45 | 38 | 41 | 2.0 | 5 | 7 | 9.1 | +0.8 | |||||
| FU07SC | FU07SS | FU07SUS | M35x1.5 | 52 | 44 | 48 | 2.0 | 5 | 8 | 10.2 | ||||||
| FU08SC | FO08SS | FU08SUS | M40x1.5 | 58 | 50 | 53 | 2.5 | 6 | 9 | 11.2 | ||||||
| FU09SC | FU09SS | FU09SUS | M45x1.5 | 65 | 56 | 60 | 2.5 | 6 | 10 | 12.5 | +1.0 | |||||
| FU10SC | FU10SS | FU10SUS | M50x1.5 | 70 | 61 | 65 | 2.5 | 6 | 11 | 13.5 | ||||||
| FU11SC | FU11SS | FU11SUS | M55x2.0 | 75 | 67 | 69 | 3.0 | 7 | 11 | 13.5 | 0.07 | |||||
| FU12SC | FU12SS | FU12SUS | M60X2.0 | 80 | 73 | 74 | 3.0 | 7 | 11 | 13.5 | ||||||
| FU13SC | FU13SS | FU13SUS | M65x2.0 | 85 | 79 | 79 | 3.0 | 7 | 12 | 15.0 | +1.5 | |||||
| FU14SC | FU14SS | FU14SUS | M70x2.0 | 92 | 85 | 85 | 3.5 | 8 | 12 | 15.0 | ||||||
| FU15SC | FU15SS | FU15SUS | M75x2.0 | 98 | 90 | 91 | 3.5 | 8 | 13 | 15.8 | ||||||
| FU16SC | FU16SS | FU16SUS | M80x2.0 | 105 | 95 | 98 | 3.5 | 8 | 15 | 18.6 | ||||||
| FU17SC | FU17SS | FU17SUS | M85x2.0 | 110 | 102 | 0-0.75 | 103 | 3.5 | 8 | +0.3 | 16 | 19.2 | ||||
| FU18SC | FU18SS | FU18SUS | M90x2.0 | 120 | 108 | 112 | 4.0 | 10 | 16 | 20.3 | ||||||
| FU19SC | FU19SS | FU19SUS | M95x2.0 | 125 | 113 | 117 | 4.0 | 10 | 17 | 21.3 | ||||||
| FU20SC | FU20SS | FU20SUS | M100x2.0 | 130 | 120 | 122 | 4.0 | 10 | 18 | 22.3 | ||||||
| FU21SC | – | – | M105x2.0 | 140 | 126 | 130 | 4.0 | 12 | 18 | 22.3 | ||||||
| FU22SC | – | – | M110x2.0 | 145 | 133 | 135 | 5.0 | 12 | 19 | 23.3 | ||||||
| FU23SC | – | – | M115x2.0 | 150 | 137 | 140 | 5.0 | 12 | 19 | 23.3 | ||||||
| FU24SC | – | – | M120x2.0 | 155 | 138 | 145 | 5.0 | 12 | 20 | 24.3 | ||||||
| FU25SC | – | – | M125x2.0 | 160 | 148 | 150 | 5.0 | 12 | 21 | 25.4 | 0.10 | |||||
| FU26SC | – | – | M130x2.0 | 165 | 149 | 155 | 5.0 | 12 | 21 | 25.4 | +1.5 | |||||
| FU27SC | – | – | M135x2.0 | 175 | 160 | 163 | 6.0 | 14 | 22 | 26.6 | ||||||
| FU28SC | – | – | M140x2.9 | 180 | 160 | 168 | 6.0 | 14 | 22 | 26.6 | ||||||
| FU29SC | – | – | M145x2.0 | 190 | 171 | 178 | 6.0 | 14 | 24 | 28.6 | ||||||
| FU30SC | – | – | M150x2.0 | 195 | 171 | 183 | 6.0 | 14 | 24 | 28.3 | ||||||
Fuji BEARING LOCKNUT MATERIALS
| Material | JIS | ISO | BS |
| SS Low Carbon Steel | SS400 (or equivalent) | 1.0044 | 43B |
| SC High Carbon Steel | S45C (or equivalent) | 1.0503/1.1191/1.1201 | 070M46/080M46/080A47 |
| SUS Stainless Steel | SUS304 (or equivalent) | 1.4301 | 304S31 |
NOTES ON USE
Fine-U-Nuts are used for fastening critical components. When using Fine-U-Nut, strict compliance with the following is required:
A lead in chamfer equivalent to one thread pitch is required. The screw thread should be to ISO 965. (Tolerance Class 6g)
Lubricate the shaft before assembly or removal of the nut. With shafts of low hardness use a high performance lubricant.
To maximise effectiveness ensure there are at least two full threads beyond the friction ring.
The squareness specified for the mating face is achieved with a tightening torque equivalent to x2 the prevailing torque – see our literature.
Do NOT use a high rotational speed impact wrench.
Do NOT use the nuts on shafts with keyways.
Do NOT screw in the nut from the friction ring side.
Stop using the nut when excessive deformation or other fault is found in the friction ring and the clamp.
For severe or unusual applications please ask for our advice on 01202 339559.
Utilise our customised Bearing Selector tool here.
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