Editor's Comment: Time for a revolution?

By Chris Sleight10 May 2011

Chris Sleight, Editor, International Construction

Chris Sleight, Editor, International Construction

If you were to try and list the big revolutions in construction equipment over the years, what would they be? First the replacement of horses by steam power and then the diesel engine early in the 20th century. Fast-forward to the 1970s and the introduction of high pressure hydraulics changed the industry again, but since then what has there been?
Computer control has led to refinements and efficiency gains. Other technologies have improved environmental performance in areas like engine emissions and noise, and a better understanding of ergonomics and the effects of vibration have improved operator comfort. But in terms of the building blocks of construction equipment, the basics are still diesel engines and hydraulic or mechanical drive.
So 40 years on from the last great revolution in the industry - hydraulics - are we now due another one. So it would seem if you read this month's interview with Caterpillar group presidents Gerard Vittecoq and Stu Levenick.
To paraphrase their views, the rising price of oil means diesel is going to become a much less attractive fuel from an economic standpoint. What's more, there are other fuels out there that are inherently more attractive. Look at natural gas for example, which produces much less CO2 when it is burnt than other fossil fuels.
The other, more radical idea is to use engines as onboard electrical generators, rather than linking them up to mechanical drives, with machine functions being taken care of with electric motors. Diesel electric trucks have of course been around for decades in the mining industry, and Caterpillar has taken the concept further with its D7E dozer, which is +25% more fuel efficient than conventional machines. This is because there are so many losses in mechanical drives due to friction between all the moving parts.
And there are other advantages too. Electrical systems are simpler due to the reduced number of moving parts, and they are easier to configure because you only have to route wires around a machine instead of mechanical linkages and hoses. Another important point is that the engine can run at a steady state as a generator, rather than revving up and down, which improves fuel efficiency and will also prolong its life.
And then of course there is the idea of purely electric machines. Again, these are a feature of the mining industry, with equipment like semi-stationary face shovels being powered by electricity. This is idea is already being embraced in other areas - look at the electric compressor Doosan launched at ConExpo in reaction to the spiralling cost of low emission diesel engines.
But what about battery powered mobile machines like the battery powered mini excavator Hitachi showed at Samoter? One of the great advantages in construction equipment is that, unlike road vehicles where the weight of batteries is a penalty, in our industry many machines need that extra mass as a counterweight.
Maybe not next year, but soon I think you will find yourself plugging in construction equipment to charge overnight instead of filling the tank with diesel.

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