Feb 19, 2020 Aggregates blog

Safer and easier fastening of jaw dies

Fastening crusher jaw dies is not an easy task. To ensure that the hammer screws are tightened properly and securely, heavy hydraulic tools are needed. That makes working on the difficult-to-access hammer-head screw-spring units clumsy and complicated. In addition, if the screws are not well fastened, the jaws might drop and damage the crusher. Tri-Nut makes fastening crusher jaw dies safer and easier.
Tri-Nut System for fastening crusher jaw dies.
Tri-Nut System for fastening crusher jaw dies.

Tri-Nut has its origin in the exchange of ideas between your on-site experts and our service staff in the field. In contrast to the traditional solution using double nuts, fastening jaw dies, using the Tri-Nut system can be done by hand and with light-weight tools. Only three small screws must be tightened, which can easily be loosened again later. Using the Tri-Nut system, you can easily gain a couple of hours during jaw dies changeouts. The noticeably reduced maintenance breaks lower downtime and operating costs and ensure you run a safer workplace.

This fastening system can be used to replace the normal hexagon nuts on all models of the Nordberg C-Series jaw crusher and can also be used on other jaw crushers, considering the available thread sizes (M30, M36 and M48).

A set consists of a special nut and three hexagon screws and replaces the normal hexagon nuts on each hammer head screw and spring unit. One Tri-Nut replaces two normal hexagon nuts. The number of hammer screw spring assemblies varies depending on machine / jaws. So if there are 16 spring assemblies in a C110 jaw mounting, there are normally 32 hex nuts. If you replace those with the Tri nut solution, you will need only 16 tri nuts. Since 2019, almost all Metso jaw crushers have been delivered with the Tri-Nut fastening system. Customer Service is a mutual exchange, not just eliminating a specific customer problem, but also working together on the sustainable optimization of a situation in need of improvement.

How to correctly install a Tri-Nut

  1. Remove the jaw die hammer screw hex nuts. When only replacing the hex nuts, remove the hex nuts from one hammer screw at the time.
  2. Before installing the spring assembly, make sure that it is constructed as shown in the picture below.
Tri-Nut installation manual.
  1. Install the spring assembly. The cup springs (2) are not yet tensioned.
  2. Tighten the Tri-Nut until it touches the washer (1). The Tri-Nut is rotated to the hammer screw by hand. 
Installing Tri-Nut

The cup springs (2) are not yet tensioned.

 Tri-Nut is tightened.
Tri-Nut is tightened but cup springs are not yet tensioned.
  1. Tighten the Tri-Nut bolts (blue) to achieve right tension in cup springs. The washer (1) must be on same level with the spring casing edge (3).
Tri-Nut installation image.
  1. Check the compression of the cup springs (washer on the same level with the spring casing edge) shortly after re-start of the jaw crusher. Retighten if necessary.

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