Auto-Lok nuts are all-metal self-locking nuts for demanding industrial applications, where vibration, temperature changes and strict safety requirements make standard nuts unreliable.
Get to know Auto-Lok self-locking nuts
Auto-Lok nuts are high-performance self-locking nuts designed to combine safety, functionality and reusability. Their double-slotted design delivers consistent prevailing torque without deforming or damaging the bolt thread.
They are ideal for industries such as rail, energy, heavy machinery and transportation, where fasteners must stay tight under vibration, load and extreme temperatures.
Key benefits of Auto-Lok nuts
- Dual locking slots for secure, reliable locking.
- Suitable for automatic assembly in Class 8 and 10 applications.
- High resistance to mechanical loads, temperature and vibration.
- High reusability with consistent performance over multiple cycles.
- Stable, predictable locking performance for safety-critical joints.
- Multiple materials and plating options to match your environment.
- Simple, one-piece functionality – only one component to assemble.
- Certified to European rail standard CF 00-040.
- Network Rail approved: PA05/03451.
- Reusable up to 5 times with minimal performance loss (ISO 2320).
Plating & material options
Auto-Lok nuts can be supplied in different base materials and coatings to match your corrosion and performance requirements.
Plating options
- Zinc plated
- Dacromet plated
- SITAL BHT (anti-galling)
- Copper plated
Materials
- Class 6–8–10–12 steel
- Stainless steel INOX A2 / A4
- Brass
- Aluminium
- Titanium
Technical advantages of Auto-Lok nuts
No thread damage
A double-slotted Auto-Lok nut does not deform the bolt thread. Standard deformed nuts can crush or mark threads, forcing you to replace the bolt or repair (“chase”) the thread. This is time-consuming, costly and sometimes impossible in the field. Auto-Lok nuts avoid this problem and help preserve the integrity of the bolt.
Reusability
Auto-Lok double-slotted nuts can be reused at least five times while maintaining almost unchanged removal prevailing torque, thanks to strict manufacturing standards. They are specified in demanding rail applications, including French high-speed trains (TGV) and other rolling stock.
Vibration proof
The locking mechanism delivers excellent vibration resistance. Performance is unaffected by oil, petrol or other liquids and vapours. Once correctly tightened, the self-locking nut will not come loose under normal service vibration conditions.
Consistent torque & extreme conditions
Consistent locking torque in line with NF EN ISO 2320 ensures predictable assembly and removal. Different torque levels can be specified if your application requires a specific prevailing torque range.
Temperature resistance: Auto-Lok® double-slotted nuts operate reliably from –50 °C to +450 °C, making them suitable for extreme cold, heat and rapid temperature changes.
Corrosion protection: by choosing the right material and plating, Auto-Lok® nuts can be tailored to standard industrial, outdoor or more aggressive chemical environments.
Benefit
Tough and versatile, Auto-Lok is one of the most adaptable self-locking nuts for demanding industrial applications.
Suitable for multiple environments, Auto-Lok nuts perform in both high and low temperatures without loss of locking performance and are resistant to many chemicals.
A wide range of finishes and coatings is available, and the low prevailing torque allows repeated assembly without damaging the thread. The double-slotted Auto-Lok ALNd can be assembled with the locking elements leading onto a male thread.
Fast
Whether it’s delivering product on the requested date or answering a technical question quickly, Auto-Lok support is there for you.
With rapid responses to enquiries and a dedicated technical team, we help you find the right solution for your application without delay.
Lean on more than 20 years of experience with self-locking nuts and global deliveries to customers in many industries.
Definition
Auto-Lok nuts are self-locking nuts that are gentle on bolt threads yet superior in safety and functionality.
They support efficient production, especially when many different types in smaller quantities are required.
Self-locking nut: a nut that provides prevailing torque without the need for a separate locking element such as a washer. Auto-Lok achieves this with a single component, reducing assembly time and parts count.