The Rise of the Excavator

Reprinted with permission from ACP Media. (Deals on Wheels - Issue 161.)

Innovation has made the excavator king of construction

Back in 1956, wee lads used to sneak out to see a marvellous machine that had turned much of the flat land around Clyde in Central Otago into a vast landscape of shingle. It was “EARNSCLEUGH”, the last working gold dredge in the area, and when built in 1939 it was the last word in gold excavation.

You could hear the groaning and screaming for miles and it sounded like a mammoth monster giving birth. Coming over a mountain of tailings you looked down on a puddle of dirty water with a huge corrugated barn floating on it, at the front of which was an enormous arm of buckets picking up earth and dragging it into its bowels.
What went inside was a complete mystery but a conveyor belt sticking out the back deposited shingle behind it in an unending stream. Even then you could understand that the days of contraptions like this were over. It was built for one job only, and obviously it had more than one person driving it and needed to take its puddle everywhere with it.

Today just over the hills from Clyde, one of the largest mining excavators in New Zealand works around the clock at Oceana Gold Ltd’s Macraes Operation. The huge Hitachi 3600-5 excavator gulps up just as much ground using its 22m2 bucket to get 39 tone bite and it is controlled by one operator. What makes this possible?

War did, really. During the WWII and the cold war period that followed, research and development into tank design (hydraulics and diesel engines) and aviation (metallurgy and high pressure hydraulics) increased dramatically. The availability of this technology in the late fifties coincided with the development and need for a fully tracked, 360-degree back hoe style digger that up until then had mainly relied on wire rope type pulley systems. The rest, as they say, is history.

Since then, hydraulic armed multi-purpose excavators have come to dominate the market. Gone are the draglines that cut ditches, gone are the grade-all style truck mounted road excavators, and tractor mounted backhoes are getting fewer and fewer. Who needs a Hamilton crane to lift pipes into place, and why hire a demolition ball crane for smaller structures when all you need to do is drive into it?

The popularity of the excavator can be easily summed up – it’s versatile. With available attachments it can dig, break stones, scoop up soil and rocks, vibrate fill, drive in fence posts, drill holes, mole plough, cut concrete and metal, grab all sorts of things, harvest trees, lift all sorts, poke holes in things, fight fires and so on. Farmers can use them to dish out silage, clean drains, drill post holes, and build culverts. They are small, big, very small and very big.

There have been many improvements over the last thirty years - more powerful engines, better hydraulics, quick hitch coupling, joy stick controls, dozer blades and a slew of attachments. Offset booms and zero overhang have improved performance and productivity in enclosed work places. At times there seems to be as many excavators about as cars and they are as useful. The key word is productivity, and that is the reason they are so popular – they improve the productivity of any operation they are used in.

Interestingly although we have used them here in New Zealand for thirty odd years, incredibly the Americans only cottoned on to them in the last ten years or so. In the 1970s and 1980s, the US sales were less than 10,000 units a year and it wasn’t till this century that they crept up to 20,000 units.

What will we see in future developments?

Tier 3 power trains are arriving already. They have more power output with greater loadings to improve productivity while saving in fuel economy. Machines will become quieter with features like repositioned engines, more insulation, improved mufflers and anti vibration mounts. More ergonomic cabins with vastly improved comfort, visibility and safety also are coming.

The trend toward “intelligent” equipment will continue, where the engine, transmission and hydraulic system electronics are integrated into one system, improving efficiency and performance. Environmental considerations will result in the wide use of water-based paints, biodegradable lubricants, improved emission controls, and recyclable components.

Some technical refinements of present systems have already brought performance gains, eg the reduction of oil flow resistance which increases hydraulic horsepower; improved access to service needs with modular components will improve serviceability and remote sensing for scheduling maintenance will reduce down time.

Experimental operations overseas are trialling remote control so an operator can operate the machine from hundreds of yards away in inhospitable terrain (radioactive) but which could have applications in other unsafe environments. Other tasks could ecome routine and have one operator operating several robotic machines. All this in the name of productivity.

These coming innovations and ones yet to be presaged are certain to continue the reign of the excavator as the king of construction.

By Graham Scott

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