Eliminating Loose Bolts on a Class 1 Double Diamond with THU Locknuts
A busy Class 1 double diamond faced frequent loose and seized bolts, causing weekly maintenance headaches and high costs. J.Lanfranco THU locknuts provided predictable locking, eliminated weekly replacements, and saved $50,000 in six months.
Replacing Weak Fastener Technology with a Better Solution
The Challenge: Unreliable Fasteners Disrupt Railway Traffic
A Class 1 double diamond in the American Midwest handles heavy traffic from four different railways. Inspections revealed a critical problem: almost every bolted joint was either loosening or completely unloaded.
- Locking washers were shattered.
- Nuts no longer provided any prevailing torque.
- Maintenance crews faced roughly 60 loose or broken bolts per week, requiring 3,000 replacement assemblies annually.
Track maintenance occurs while trains are running, leaving crews minimal time to work safely. Seized nuts during installation or removal forced weld crews to cut fasteners free, sometimes damaging through holes and increasing maintenance costs.
The root cause: the existing prevailing torque nuts used deformed threads, producing irregular torque. Some nuts failed to lock, while others seized during installation. Over time, repeated installations caused fatigue and further unreliability.
The Operational Impact: Safety, Cost, and Track Availability at Risk
The combination of loosened or seized fasteners meant:
- Frequent service interruptions
- High labor and replacement costs
- Increased risk for maintenance crews working in live track conditions
- Reduced track availability and operational efficiency
Operators needed a fastener that provided predictable locking, minimized maintenance, and could be installed safely in live conditions.
Defining a Practical Objective & Installation of THU Locknuts
To address these issues, operators selected J.Lanfranco THU locknuts.
- 70 THU nuts (1”3/8-6 UNC Gr.8) were installed using a hydraulic impact tool.
- Existing on-site bolts were reused.
- Installation was completed without problems or downtime.
The objective was clear: eliminate weekly maintenance, improve track safety, and maintain bolt integrity over repeated inspections.
Proven Results: Reduced Maintenance and Significant Savings
Since installation:
- No loosening has been observed during inspections.
- Weekly changeouts have been eliminated.
- Over six months, the site saved nearly $50,000 in labor and replacement costs.
THU locknuts corrected flawed bolting installations, improved maintenance safety, and enhanced track availability—all without altering standard procedures or requiring specialized fasteners.