Railway Applications

There are many applications where threaded fasteners can loosen because of shock & vibration caused by trains.

Hardlock Nuts are a product that resists loosening by vibration. It enhances safety, improves reliability and reduces inspection and maintenance costs.

Japanese Railways have specified Hardlock Nuts for more than 40 years. In the UK, Network Rail have specified Hardlock Nuts for over 10 years, with new applications being added to all the time.

The Hardlock Nut is the best solution for nut & bolt assemblies on railway track, turnouts, crossings and overhead power systems.

The Problem

Vibration can loosen all bolted joints.

The Railways are a challenging environment, and the loosening of fasteners can have catastrophic results. For decades the railways of the world have struggled with this problem. Some solutions have proved to be better than others.

Increased frequency of inspection and maintenance is not a cost-effective solution.

Japanese Railways and Network Rail have specified that Hardlock Nuts be fitted as a solution to loosening, eliminating broken bolts and missing fasteners. More applications are being identified and the problems are being solved by using Hardlock Nuts.

Vibration can affect a whole range of applications causing multiple failures, as illustrated in the images opposite.

UK mainline points system

Stretcher Bar Bracket

The Solution

The Hardlock uses a mechanical principle that makes it unique.  This is how it works:

The Hardlock functions by utilising two nuts that work together.  The cone on the lower nut is off-set, so that when tightened against the upper nut, vertical and horizontal locking forces engage the screw thread.

Explaination about how the Hardlock Nut works in a selection of languages can be found here.

The Evidence

As a result of a number of fastener failures in the rail industry comprehensive mechanical tests were carried out during 2006.  The conclusions of this report was made public. (RAIB 20/2008)

This video shows comparative performance of fasteners against the Hardlock Nut when tested using a Junkers vibration machine to DIN 65151 (2002).

Great Britain – Network Rail

The Hardlock Nut is used extensively on Network Rail infrastructure and is now standard across a number of applications.  The latest certification is for Hardlock Nuts for use on fishplates.

For the full story read this Rail Professional article – click here

The Hardlock Nut has now recieved updated certification to include its growing deployment across track applications.  Click on the image for a detailed view.

Would you like a depot demonstration?

Staytite is now taking bookings for Network Rail depot demonstrations.  Click here for more info.

Australia – QR Network

Hardlock is used extensively throughout the Australian railway network.  Click on the image for a detailed view.

Japan – Japanese National Railways

Hardlock is used extensively throughout the Japanese railway network including rolling stock, track and infrastructure.