THE NEED
Western Australia is blessed with a wealth of minerals. It also has a lot of swampy salt lakes. The search for minerals sometimes requires heavy drilling rigs to traverse the salt lakes to drilling locations. Getting bogged is not unusual and rescuing bogged drilling rigs is even more challenging. Drill rig operators are often forced to trade-off the quantity of supplies they wish to bring onto a salt lake with the need to restrict the total weight of the drilling rig and support equipment.
Western Australia also has an emerging salt lake potash industry with two projects aiming to commence production in 2020 and five other projects being pursued. The projects will be operating on swampy salt lakes with the same challenges as the drilling industry.
THE PROBLEM
The industry standard approach for many years has been to create an oversize track assembly with extra width using mild steel RHS sections, increasing the track’s surface area to reduce the ground pressure. This has enabled the drill rigs to get onto the salt lakes, but has suffered from several problems:
- The RHS swamp tracks support a lot of weight. The mild steel RHS tracks are easily bent if the drill rig travels over any surface that creates an uneven weight distribution on the tracks.
- The mild steel RHS sections add substantial weight to the drill rig, reducing the pay load that can be taken onto the lake and/or increasing the risk of being bogged.
- The gaps between the RHS sections open up as the track travels over the final drive and idler. The gaps close up when the track is in the weight bearing position (underneath the body of the drill rig). The continuous opening and closing of the track pads can lead to stones being trapped between the RHS sections which causes structural damage to the track.
- The RHS sections act like a continuous steel plate when they are in the weight bearing position with minimal gap between them. This reduces the surface grip, particularly on clay type surfaces, which increases the risk of slipping and bogging of the drill rig or crawler vehicle.
THE SOLUTION
Goldmont Engineering has designed the Trapezoid Swamp Track using Hardox® hardened steel. The advantages of using the stronger and lighter steel are:
- The tracks are much more robust thanks to the higher yield strength of Hardox® steel and users can expect a much longer service life. They will flex and return to their original shape when travelling over small rocks or uneven surfaces. This was demonstrated by workshop testing of 1.4 metre lengths of the trapezoid profile used in the Goldmont Trapezoid Swamp Track and the 1.4 metre length of two (welded together) 75x75x5mm RHS profile used in the “industry standard” swamp track. The trapezoid profile returned to its original shape after 40mm deflection. The mild steel RHS profile did not rebound after as little as 5mm of deflection.
- The tracks are 70% lighter than the “industry standard” tracks, thanks to the high strength to weight ratio of Hardox® steel. This translated to a 1,265kg weight saving on the first crawler vehicle built by Goldmont with the trapezoid tracks.
The benefit of Goldmont’s trapezoid shaped design is the retention of a space between the sections when the swamp track is in the weight bearing, flat portion of its travel. This means:
- less chance of stones damaging the track by being trapped in between the sections; and
- more grip on the swampy salt lakes because the swamp track is not acting like a flat plate. More grip means less chance of getting bogged.
“The answer is simple once you’ve seen it”
