Hardlock Nuts

Steelrod is the Australian distributor for Hard Lock (HL) anti-loosening lock nuts - nuts that do not have to be seated and require only a spanner to install. 


Hard Lock Nuts are designed to withstand loosening from vibration and are ideal for use in a range of applications including; Industry:- Public Sector, Electricity & Gas, Construction, Iron and Steel, Cement, Electrical Machinery, Transport Machinery, Ship Building, Nuclear Power, General Industrial Machining. (See below for applications).

They are available in a variety of materials with a range of surface treatments to meet the needs of varying applications. Shapes include standard, semi-thin, thin and round, with custom shapes available as an option. Semi-thin and thin Hard Lock Nuts are also available.

locking mechanism

They have been tested and last longer than any other fastener on the market. Ideal for critical mechanical applications, the Hard Lock ensures a secure connection for enhanced safety and reduced maintenance and inspection costs as they can be reused dozens of times with no reduction in performance.

The hexagon nuts work on the same principle as a wedge. When a wedge is driven between two fixed objects a strong unifying force is exerted on both. A wedge driven between two surfaces in conjunction with a bolt creates a powerful anti-loosening effect.

Hard Lock nuts incorporate this principle into the nut itself. The lower nut has an eccentric, tapered convex cone machined onto the top face. The upper nut has a concentric tapered concave spigot machined into the bottom face. As the upper nut is screwed down the bolt, the tapered spigot comes into contact with the tapered cone and a locking torque between the two nuts is generated.

Alternatively, the assembly can be inverted, with the lower nut tightened onto the upper nut with the same results.

locking mechanism

Hard Lock nuts are maintenance free, saving users inspection costs as well as losses incurred by loosening. They meet the American National Aerospace standards NAS3350 and 3354 for vibration and impact resistance.

The nuts are available in a range of metric and imperial sizes. They are available in semi-thin and thin types.

The semi-thin nuts are approximately 85% the size of standard nuts. They are useful for applications where a narrow nut is needed but substantial tightening torque is still required. Thin nuts are approximately 70% the size of standard nuts. They are useful for applications where anti-loosening properties of the nuts are more important than the locking force.

The nuts are available in low carbon steel, high carbon steel, and AISI-304/316 stainless. Zinc-plated and hot dip galvanised finishes are available. The nuts are made to equivalent classes of  4.6, 8.8 and 12.9.

locking mechanism
locking mechanism

Steelrod also distributes Hard Lock Bearing Nuts (HLB) which require only a hook wrench to install. They do not require a tooth lock washer or any keyways to the shaft. They offer the same anti-loosening properties, impact resistance, and vibration resistance as the HL nuts.

The anti loosening properties of the Hard Lock Bearing Nuts allow them to be rigidly positioned at any point along a threaded shaft. When the lower nut is not seated, it is held in place by a wrench while the upper nut is tightened. These nuts can be used for adjusting tapered roller bearings or thrust bearings, or to hold critical position after minute adjustments to machinery are made.

Both nut types are used in a wide range of applications including railways, highways, bridges, skyscrapers, industrial machinery, mechanical structures and in any application where a superior lock nut is required. 

locking mechanism

locking mechanism

Contact Details

Steelrod Pty Ltd

3-7 Sodium St

Narangba QLD 4504

07 3888 2341

ABN: 89 009 934 810

This email address is being protected from spambots. You need JavaScript enabled to view it.

Screenshot 2020 12 03 Steelrod1