In my last article 'Ultra by name, ultra by class' I referenced the increasing size of haul trucks used in Mining, with the largest truck now able to carry a whopping 450 metric tons. While no one would argue that they're not an engineering marvel, the machines designed to load these trucks are in many rights the top of the apex and the kings of their jungle. Be it a digger aka excavator or face shovel, these machines are being built to be bigger, faster and more reliable to meet the ever-increasing demands of society. With so many moving bits, these giants of the 'sand pit' (and excuse me if I'm sounding a little like David Attenborough here) work around the clock in some of the harshest and most intolerable conditions known to man.
As a frontline machine, such excavators are expected to work an average 6,000 hours per annum swinging backwards and forwards, up and down, day and night. These large diggers can be acquired in two configurations, the first (and most popular in Australia) is known as a hydraulic excavator, with the second called a face or front shovel. Fit for purpose, the key difference between these machines relate specifically to the way they dig dirt, where one pulls material towards itself (excavator/backhoe) and the other (face/front shovel) moves in an upward motion moving material away from the machine. With a high break force, the front shovel is particularly good at excavating heavily compacted dirt and rocks and because of its short boom and stick, must be closer to the material it is digging.
Fitted with buckets (the big 'scoop' at the front of the machine) these machines carry large capacities of material and are primarily used to load heavy-duty haul trucks. In the case of the front shovel, buckets come in two formats, front or bottom dumping. In bottom dumping shovels, the bucket separates in the middle, so that the material can drop through the bottom like a trapdoor instead of tilting the bucket forward and dumping out the front. Simply amazing. Alas, like any high performer, these machines are measured upon the amount of dirt they can move, in the shortest possible time. In an industry where time is money, and metric tonnes directly correlate to dollars earned, terms such as 'swings', 'pass overs' and 'cycle times' are common on a mine site. Put simply, they give an indication to just how quickly they can fill the truck their loading so that the next truck can takes its place.
Want to know more, just have a look at the video below to see firsthand the sheer volume of material these machines can carry.
This article was originally published by the Components Only team in the April - May 2017 issue of "@ The Coal Face" magazine.Published 20 April, 2017