Locknuts J.lanfranco Railroad track tools parts critical joint barsJ.Lanfranco THU locknuts were designed to help railroads solve an age-old problem: waste. A waste of money, a waste of time, and a waste of parts. These self-locking nuts are proven to greatly decrease railroad track maintenance time, broken components, and damage to castings. Locknuts that will diversely lower your expenditure, and help your company and the railroad stay on budget and on schedule.

The traditional nut-and-lock-washer method used on critical bolted joints requires regular labor every other day for tightening (or at the very least, once per week) to maintain normal operation. THU’s built-in self-locking technology has been proven in the field to hold tight without loosening, regardless of the amount of vibration your critical joints endure. And unlike other locking systems that require the purchase of both a locking nut and a bolt, J.Lanfranco’s nut sizes are compatible with any standard bolt on your joint and can be installed with standard tools such as an impact wrench. This makes them ideal for smaller crews working in remote areas.

The efficiency, reliability, and proven track record of J.Lanfranco’s THU locknuts will lead to tremendously lower labor costs, a reduction in track maintenance and service interruptions, and fewer damaged components and castings.

What are they?

THU is a dual-slotted, all-metal, self-locking hex nut. Its full-height, single-piece design requires no inserts. And because the dual-locking slots function independently of bolt tension, the parts can be removed and reused. They possess superior resistance to vibration, shock, and impact, so the nuts stay put even when subjected to heavy train loads.

How do they work?

As the nut is tightened onto the bolt, the locking slots expand and tightly grip the thread flanks of the bolt, locking it in any position. The locking torque applies evenly over two planes and on opposite sides. These anti-galling nuts resist adhesive wear, can be reused, and are immune to corrosion even at extreme temperatures. Simple to install and remove, they require no anti-seize paste or grease.


J.Lanfranco locknuts were installed and marked on this critical joint in early summer. Industry Railway’s product management team returned to inspect them midwinter and confirmed they had not loosened, proving that THU’s performance is unaffected by extreme temperatures.

J.Lanfranco locknuts were used on one of the busiest diamonds in Eastern Canada. When checked more than a year later, the locknuts showed no signs of loosening, according to company officials.













Quick install of the THU on a critical joint