Any machine with moving pivots will inevitably experience lug wear. The most common occurring to machines in applications such as mining and construction, where they are subjected to heavy loads and vibrations. In fact, any moving pivot in just about any application will experience lug wear at some point.
Three main reasons why lug wear or pivot wear is inevitable when using straight pins:
1. Lugs are typically made from softer material than the pin. This causes them to deform when the two meet.
2. There is no pressure distribution in the lugs, due to the play between the lug holes and the pin (which is needed to mount the pin). When the pin is loaded, all pressure from the pin is forced onto thin lines in the lug holes.
3. The play enables the human force being applied to the pin to hit the lug holes with full power, as the equipment’s moving direction changes.
The three most common solutions to lug wear (and not the best solutions) are:
1. To repair the lugs with welding and line boring. The first step in this process is to unload the pivot and dismount the pin. The line boring equipment is then required to be lined up and mounted to the equipment. The worn lugs are rebored, filled with weld and finally rebored with a fine cut to the original diameter and tolerance. After removing the line boring equipment and repainting the lugs, a new replacement pin is installed.
This entire process can take anywhere from a few hours to a few days depending on the size and complexity of the installation and during this time, the machine cannot be operated adding to the already hefty maintenance costs.
2. Using a pin that fits as tightly as possible in the lugs holes, eliminating any play between the two. This option not only makes the pivot expensive and difficult to mount, but overtime the lug hole will eventually expand anyway.
3. The temperature method is the third method commonly used and is where the pin is frozen and then allowed to get warmer and expand, creating the perfect press fit in the lugs. A common misconception is that pivots with frozen axles are maintenance free, where as they are actually impossible to maintain, due to the difficulty in removing the axle.
Unfortunately, none of these options will ever completely remove the need for costly and time-consuming lug repairs, with lug wear inevitably returning and the repair procedure needing to be repeated. In a typical application, this occurs three to four times during a machines lifetime or every 3,000 to 4,000 hours. If the Expander Pin System is used pivot wear is eliminated for good and the long term cost savings can amount to thousands of dollars for each machine by avoiding the pitfalls of conventional lug wear methods.
The Expander System has a pin design with tapered ends and an expanding sleeve on each side. When installed, these sleeves expand radially to fill the lug, creating an exact press fit. As the sleeves expand into the lug, they can take up the unevenness or deformity in the lug eliminating the need for welding and line boring and significantly reducing the time needed for installation and downtime. Couple this with the manufacturers 10 year or 10,000 hours warranty and the Expander Pin System is the only solution when it comes to pivot wear.
Contact Fortus on 1300 363 969 or [email protected] and our customer support team will assist you in choosing an Expander Pin System for your machine.
