Still digging it

Don't bring a shovel to an excavator party. Here's a brief history and guide to the diggers in the region.

Not ideal for tight city centre jobs
Not ideal for tight city centre jobs

Don't bring a shovel to an excavator party. Here's a brief history and guide to the diggers in the region.

Those who have spent any period in the UAE should know the concept of 'Dubai time'. For those that don't, Dubai time is the tendency to over-promise on schedules that are by any standard, ridiculously tight.

This is particularly true in the construction industry, and in a city where time is money, the machines have to work around the clock if there is to be any hope of hitting an impossible target.

Perhaps the easiest way to keep on track is to ensure the earthworks are delivered on schedule, and no machine does this better than the hydraulic excavator.

As they have been imported, often secondhand, into the Emirates from all four corners of the globe, it is not unusual to find many kinds of rare breeds puffing out smoke in foundation pits and road projects everywhere, though spares availability keeps some going longer than others.

Steam shovel

While many of the machines are bruised and battered, most of them conform to modern design principals. However, excavators date back to the first half of the nineteenth century, when a chap named William Otis placed the first 'steam shovel' on the market.

This rail-mounted machine was patented in 1835, and looked as if it were powered by clockwork, as the flywheel and various cogs for the lifting gear were exposed for all to see (or walk in to). Although Otis died shortly after the contraption went on sale, iron-clad patents stopped anybody else from building a digger for a whole fifty years.

After the expiry, though, several firms, including familiar names such as Bucyrus and Priestman entered the market. Perhaps the largest early project completed with the aid of mechanisation was the Ship Canal dug in Manchester, England starting in 1887. Here. 58 Ruston steam shovels worked alongside 18 Priestman 'Clamshell' excavators as well as numerous other machines, including 173 locomotives, with 6,300 rail wagons to move 1.2 million cubic yards of dirt per month - far more than could be achieved by any amount of men with shovels.

Of course, these early machines were unwieldy, as they needed rail to be laid in order that they could move, the boilers needed a lengthy time to get up steam and of course the mechanism was cable operated rather than hydraulic.

Still, this didn't stop the 100-odd diggers moving 255 million cubic yards to build the Panama Canal a few years later.

Hydraulics

Cable machines remained the dominant technology right up until the 1940s. Though some experiments had been tried with hydraulics as far back as 1882, it wasn't until Bucyrus-Erie produced the 'Hydrohoe' in 1948 that a modern, fully hydraulic machine was readily available. This was a truck mounted backhoe, which had the functionality to become a small crane.

French first

However, it was the French firm Poclain that scored success with the first major selling hydraulic excavator. In the 1950s it developed the TY-45, an odd looking machine.

Unusually, the excavator did not use tracks, instead it had a skateboard like chassis, with a pair of rear driving wheels and an inboard third wheel (actually a double axle) for steering. It could also be towed reasonably easily behind a tractor or large truck. With more than 30,000 units sold, it remains the best selling excavator of any type, to this day.

Unusually, Caterpillar were reasonably late in putting a range of excavators on the market, with the first model, which was numbered 225, not being put on to the market until 1972. Models 235, 245 and wheeled 'rubber duck' model 214 appeared later.

All were extremely popular and remained in production until replaced by the 300-series. The 200 series is still extremely common across the GCC, with good spares support from regional Cat dealers Al Bahar and Zahid Tractor, though it's sucessor, particularly the 20-tonne model - remains the most common model by far across the region.

Another popular brand across much of the world is Case. This was an early name to the world of construction, as founder Jerome Increase Case demonstrated his first machine, a wheat thresher, back in the 1830s.

However a move to petrol in the 1890s, and then an early form of diesel in the early twentieth century made it an early player in the tractor market. After a complex string of mergers and acquisitions, the brand now produces the full line of construction machinery. Interestingly, while most of the firm's line-up is a distinctive orange, the excavators are construction yellow.

Japan

For a long time, companies in Europe and America had it their own way with the design, sale and manufacture of construction equipment.

However, it didn't take long for the Japanese to respond with the Hitachi Construction Machinery Company launching in 1965 a machine named UH03 - the first to be produced using Japan's own technology.

Today, Hitachi controls a major portion with HCME supplying machines to the Middle East, Africa and Europe. In the UAE Hitachi are distributed by Kanoo Machinery, and the region has just seen the arrival of no less than four giant 518-tonne EX5500 machines for work on a large infrastructure project. Speaking earlier in the year Allan Callaway, general manager, Kanoo spoke about opening a new workshop in Jebel Ali.

"If you look after the sales support, the sales will look after themselves and it sure doesn't happen the other way around" he said.

Hybrid power

Even larger than Hitachi, Komatsu has moved from humble beginnings. In the late 1960s it was tied in with Bucyrus-Erie to make hydraulic excavators. This deal was terminated in 1981 and today the firm is the largest manufacturer of excavators in the world, in terms of units sold at least.

In the UAE, the firm is represented by Galadari Trucks, with one of the most popular lines being the PC-200 series. However, one model in this range that won't be finding it's way to the Emirates just yet is the all-new PC200-8 Hybrid.

Currently only available in Japan, the machine offers real-world fuel savings between a quarter and a half, by using an electric motor to slew. This is powered by rapid-discharge capacitors charged by the engine, rather than the battery-electric combination used in other prototype construction machines.

If the machines sold in Japan prove successful, then the company has said the excavator will become a global product. This will be welcome given the soaring, yet disparate price of diesel across the Emirates.

Bucket wheel

Electric power, of course is nothing new in the world of excavators. The giants of the world's coal fields have been using electric motors for years, as no diesel would be able to provide the power and torque needed to operate such things.

Despite being electrically powered, not even the best PR could market these machines as being ‘green' as they routinely hog enough power to run 12,000 homes - as well as spending the day strip mining the landscape.

However, power consumption is at least steady and can be accurately projected.

Of these behemoths, the largest - and indeed the largest land vehicle in the world is the German-built Bagger 288. ‘Bagger' just means excavator in German, though technically this is a strip mining bucket wheel. Weighing 13,000 tonnes, the device was constructed for removing overburden at a mine in a place called Hambach, Germany.

The numbers about this vast machine are vast. It can excavate 240,000 tons of coal or 240,000 cubic meters of overburden daily - the equivalent of to 30 meters (98.4 ft) deep. The coal produced in one day fills 2400 trucks. The excavator is approximately 240 m long and 96 m high.

The large surface area of the tracks means the ground pressure is very low - about 24psi. This allows the excavator to travel over gravel, earth and apparently even grass without leaving a significant track. It has a minimum turning radius of approximately 100 meters, and can climb a maximum gradient of a steep 1:18.

The excavating head itself is 21.6 m in diameter and has 18 buckets each holding 6.6 cubic meters (7.9 yd3) of overburden. Incredibly, when it had cleaned out its first mine, the Bagger was 'driven' some 22 kilometers to another pit.

With no end to the construction boom in sight, one thing is for certain; We'll be still digging it for a long time to come.

Used Excavator checklist

1. The condition of the engine in any excavator is most important. Look for smoking from the engine and usual sounds coming from it.

2. Check the tracks. If at standstill they look to be sagging, then expensive repair bills will be required.

3. Obviously, the machine shouldn't be leaking any hydraulic fluid.

4. The more you know about a particular machine, the less likely you are to by a poor example. If you always by from the same firms and you know something about the way they train their operators, then you are much less likely to have a problem than buying an unknown machine.

5. Put it into gear and it should start moving. Put a wooden block in front and then put it in the forward gear and the truck should have the power to jump over.

6. Check the service history to see what has been replaced, and what needs to be changed soon.

7. Check the stick and the boom. They should not have been rewelded.

8. If the machine is a 'rubber duck' (wheeled excavator), check the tyres.

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