Ensuring Smooth Railway Traffic with the THU Locknut
Recurring fastener loosening at a busy railway diamond meant daily inspections. See how THU Locknuts solved the problem and maintained reliability in extreme conditions.
Fastener Integrity Is Critical to Reliable Railway Operations
The Challenge: A High-Risk Diamond Under Constant Stress
One of North America’s largest Class 1 railways had to contend with the ongoing challenges of operating a diamond that is relied upon by three different railways. Every year, the diamond is subjected to heavy tonnage and environmental damage caused by repeated freezing and thawing cycles.
Ongoing Loosening Under Service Conditions
After trying various locking washers, rivet-type bolts, and conventional locknuts, the only reliable method for keeping traffic moving and ensuring the integrity of the diamond was to schedule daily on-site maintenance inspections to re-tighten loosened bolted joints. In winter, the crew had the added responsibility of transporting equipment to blow snow from the track to carry out the maintenance.
Defining a Practical Objective & Installation of the THU Locknut
In December 2017, operators sought to eliminate the need for these daily maintenance visits. Working with J.Lanfranco, they installed 1”3/8 UNC Gr.8 THU locknuts using existing track bolts on both interior and exterior locations. The nuts were torqued to existing values and then monitored — at first daily, then monthly.
Clamp force was consistent even six months after installation.
After more than three months with no movement or loosened nuts, heel blocks and steps were also outfitted with THU locknuts. In February 2019, after being subjected to two freezing and thawing cycles, none of the installations experienced any loosening. And best of all, standard bolts, tools, and installation procedures were used by the crews.
Why use the THU ?