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View from the cab

PLANT HIRE

MECALAC is better known in the road-rail sector for its four-wheel drive articulated steering excavators equipped with two-piece booms to perform a multitude of ear thmoving and materials handling jobs.

But now the French maker has diversified into the more competitive mainstream excavator sector.

The 714MC is convent ional only up to the slewring and from then on embraces Mecalac's innovat ive design and its approach to producing a machine to perform a wide variety of construction tasks.

It is a short-tailswing machine on a fairly standardsized undercarriage with the option of a blade. It is available with a two-piece boom with conventional 'over the top' dipper arm operation, a two-piece boom with 'underslung' dipper arm operation, and a mono boom.

We had intended to see how the 714 performed as a standard excavator with the mono boom, but such are the demands of sales and marketing departments that the proposed test machine was out on demonstration and not available, so we opted to test the 714MC in twopiece boom specif icat ion used just as an excavator.

But we were impressed with its performance.

It has modern styling with a capacious cab and a patented door mechanism, which is a combination of sliding and slam operation that combines the advantages of both.

Naturally the KAB seat is fully adjustable and can be air suspended and heated as an option. The liquid-cooled Deutz engine is located alongside the cab; the cooling fan noise is a little intrusive but Mecalac is confident it can significantly reduce this with a revised fan design.

By preheating the fuel, the firm also reduces fuel detonation noise and as a consequence cuts noise levels by around 2 dBA.

Latest technology in hyd raulic system design combines a single element, variable, high-f low pump with a closed centre control valve. Flow sharing is determined by the travel on the control lever as opposed to load sensing and gives easy and smooth multiple service operation.

The control lever layout is conventional but the electronically controlled operating system has been designed for the professional operator and not the faint-hearted. With three power modes ? high, standard and economy ? plus two control pattern options and the facility to move some of the control functions around the joysticks to suit operator preferences, there are endless combinations on this machine.

It is necessary to explain that in ISO mode the secondary boom has to be adjusted by an addit ional foot pedal, but in the Mecalac pattern the dipper arm and secondary boom move collectively as you operate the dipper lever.

The test site was heavily compacted, built-up ground comprising very wet clay and soil ? a tough test for any excavator. Mecalac's operator chose to use the ISO control pattern in the high power mode for the tests. It's a configuration I guess most operators would choose, probably to the exclusion of all other options.

Extending the two-piece boom gives an amazing outreach of over 8 m, but only the unwise would put a loaded bucket out that far. In contrast, bringing the secondary boom in allows the bucket to be brought right up to the blade ? as a result, the length of trench that can be dug from a single position is impressive.

There is plenty of digging force, very lit tle fazed th is machine, and in Mecalac mode there seemed to be even more digging force, to the extent it was preferable to have the blade at the front while excavating to anchor the machine and prevent it from being pulled towards the hole.

Track ing can be hand or foot operated but the lever travel is excessive and uncomfortable, coupled with blade control on the left hand ISO lever, activated by a button on the back of the joystick. The two-speed tracking button is on the instrument panel and the combination of functions took a bit of getting used to.

A more conventional layout of blade lever on the right and two-speed change on the same lever would bring it line with most other makes and make it more productive.

Again there was loads of power and grip, as the 714MC performed very well.

Our operator chose to use a wide bucket to backfill the trench to demonstrate the 714's versatility. It also revealed the benef it of that except ional out reach as f rom one side of the trench it was possible to reach the far side of spoil and bring it back into the excavation. It was, without doubt, a quick method, but only suitable if you can position alongside the trench opposite the spoil and any standard excavator could accomplish the same result given correct positioning.

All maintenance can be conducted from ground level and the large access covers give easy reach to all components.

With up to 60 greasing points, it is for tunate that there is a semi automatic system that greases the main points f rom a single bank of th ree nipples, though the dipper end and bucket linkage nipples need individual attention.

Mecalac recommends intervals of every eight hours, which is a bit out of line with other modern excavators which are offering up to 500 hour greasing intervals.

Mecalac's 714MC with its two-piece boom is a mass of hydraulic pipes, wires, relays and solenoids. There's no getting away from its complexities, but in the hands of a skilled operator it will reward you with performance and a level of versatility that few others will be able to get close to.

The mono boom model needs to be a little less complicated to be attractive to UK plant hire, where there is a dependence on self-d r ive, but if it performs any thing like the two-piece boom model we tested , it will be an excellent machine.