NEWS & REVIEWS
On the face of it, the announcement that Scarab Sweepers was to introduce a new, auxiliary-engined, truck-mounted sweeper was something of a shock - perhaps akin to discovering that the Americans had, after all, decided that soccer was superior to American football, or that the French were abandoning boules in favour of cricket.
Surely, the whole thrust of Scarab marketing over the past two decades has been to insist that a single power unit - the one powering the truck itself - was more than sufficient, when coupled with a hydrostatic pump/transmission unit, to power the sweep systems.
Indeed, it could be argued that Scarab's success in world markets has been based almost entirely on this assertion. The company has undergone dramatic and constant expansion over the past two decades, to the point where it is now a major player in the domestic UK market, as well as a regular supplier of machines to Europe (France in particular), the former Eastern Bloc countries, Russia, Australia, New Zealand and other Pacific Rim markets. Of course, most compact sweepers today have hydrostatic transmission, but the purpose-built Scarab Minor has continued to sell well round the world, in spite of competition from a number of other manufacturers. Originally designed to replace the East German-built Multicar chassis, Scarab initially produced its own chassis/cab unit with a Ford engine, then a VW and - more recently and most successfully - with a compact 2.8 litre VM turbo diesel, producing 59 kW.
All Scarab Minors are hydrostatic but, in the larger truck-mounted, sector, Scarab was still in a minority, as auxiliary-engined designs remain the most common solution.
According to marketing manager Vic Beckwith, the ever-increasing demand for Scarab products has resulted in some logistical problems, particularly when it comes to the larger single-engined, truck-mounted sweepers. These require a hydrostatic package engineered into each specific truck chassis. 'The problem is that a different mounting assembly is needed for each make of truck chassis. We could, of course, bring each truck chassis into our factory in the UK for hydrostatic installation and bodying, but this is hardly practical on a large scale, or for more distant world markets, 'he explains. 'While we have set up local production facilities for single-engined, truck-mounted, hydrostatic sweepers in countries such as Australia, this solution is not always practical.
According to marketing manager Vic Beckwith, the ever increasing demand for Scarab products has resulted in some logistical problems, particularly when it comes to the larger single-enginAnother approach was required, especially as, in many previously strong markets for Scarab truck-mounted sweepers, operational changes were jeopardizing the purchase of completed units from the UK. Vic Beckwith explains: 'where open-trade agreements between the UK and other countries like Australia are in place, import tariffs have not been a barrier. But in countries where sweepers were previously purchased by government departments without import duties being incurred, today the situation has radically changed. In many cases, previously commercial contractors have replaced government-run departments. In such cases, the duty exclusions enjoyed by the government department do not continue to apply to their contractors, and with import duties running at up to 60% in some countries, this can make our equipment prohibitively expensive. 'A continuing stream of enquiries suggested the need for a long-term solution. While contending that a full hydrostatic package was the most environmentally acceptable configuration for a truck-mounted sweeper, Scarab design engineers did at least have the satisfaction of noting that, in terms of durability, reliability and everyday operating efficiency, all the other standard components that go to make up the Scarab Merlin and Scarab Magnum hydrostatic truck-mounted machines had achieved an excellent reputation in their own right. Indeed, hadn't the introduction of the gearbox PTO-driven Unidrive option on the truck-mounted ranges - originally produced for the tough, price-sensitive, UK highway-resurfacing contractor market - already made the point that Scarab machines need not always be fully hydrostatic?
No performance shortfall
Unlike the Scarab Merlin and Magnum hydrostatic machines, it was necessary to select first - or sometimes second - gear, when in sweep mode, and then start the second engine. This served to remind me how much more driver-friendly the infinitely variable Scarab hydrostatic system is when trying to match travel speed with changes in litter density. When it was necessary to stop and reverse back to clean out heavily soiled areas, reverse gear had to be selected manually, rather than with the simple forward/reverse control on fully hydrostatic Scarab machines. At least the sweeping brushes were still raised automatically when reverse gear was selected. In all other respects, the sweeping performance was indistinguishable from that of other well-established Scarab products.
Obviously, when stationary, the noise of the VM auxiliary engine mounted behind the truck cab was noticeable at start-up. Scarab uses a larger diameter suction fan than many comparable competitors and this is retained on the Mistral design, as is the option of a 5.5, 6.5, or 7.5 m3 hopper assembly. Water for the dust-spray suppression system comes from a separate 1300-litre water tank mounted ahead of the auxiliary power unit. And in all other respects - aside from the need to start and stop the auxiliary engine - the controls and features are familiar from other Scarab models. The big question is: did the presence of the auxiliary engine compromise the efficiency or power of the sweep systems? After running over surfaces covered in a carpet of wet, fallen leaves and other debris from several stormy days, I have to say that the answer is 'no'. Was there an unacceptable increase in either in-cab or exterior noise? Factory tests concluded 'not significantly', but I wanted to compare the Mistral with several other new hydrostatic machines undergoing tests round the factory. My experience was not conclusive: there is more start-up noise - indeed, as previous Scarab marketing material has pointed out, a single engine produces lower emission rates for both noise and exhaust pollution. But when sweeping, the extra noise in the cab was not as significant as I had expected, having driven a number of other auxiliary engined sweeper designs on other occasions. Why was this? Design engineer Andy Duncan provided the answer: 'We've used the same VM engine as we use on our Minor,' he explained. 'This has enabled us to use the same fluid-drive system to power the sweep systems. As well as being well proven and efficient, it enables us to get rid of the need for various drive belts, pulleys and gearbox angle-drives used by our competitors. It is simpler to manufacture and assemble, more likely to be reliable in service in harsh environments and, above all, we are sure it helps cut down on both noise and vibration'. The only minor level of vibration discernible during my test was finally pinned down as coming from the truck, rather than the sweeper installation - although Andy Duncan added that noise suppression equipment would offer additional refinements on production machines.
What started out as a project aimed at enabling Scarab Sweepers to compete more widely on world markets, has ended up as a clever amalgamation of advanced production procedures and simple common sense. The new Mistral product line is not, as might be expected, a 'me too' copy of existing competitors' auxiliary-engined truck sweeper designs. Instead, it is a fresh look at the problem of getting an efficient, modern sweeper design out into developing markets. By combining new technology with a high content of existing, well proven components from other production machines. Scarab has come up with a machine that is bound to blow new life into the sweeper market.
General Manager Dominique Declercq of 3d had the pleasure of handing over the keys to Hubert Matuzewski from Sepur to celebrate him buying the 1000th Scarab Sweeper to be sold in France. The celebration was held at the Pollutec Show in Lyon where Managing Director of Scarab Sweepers John Affleck and Jean Claude Fayat of the Fayat Group exchanged Commemorative Plaques to celebrate the efforts of those involved in this great success. Mr Hubert Matuzewski of Sepur received his new Scarab Major 5001 (Merlin) he was also presented with a 1000th Vehicle commemorative plaque from both John Affleck of Scarab Sweepers and Jean Claude Fayat of the Fayat Group of which 3d belong.
Scarab, of course, pioneered the single-engine sweeper which uses the vehicle engine to power its suction fan and brushes via hydraulic drive. The absence of the auxiliary engine, its fuel tank and cooling system used on all other sweepers in Ireland means more than one tonne more pay-load and a bigger hopper.The advantages of having only one engine are obvious, but until Scarab came along some 20 years ago the problem had been how to keep the lorry engine running at sufficient rpm to power the suction fan and brushes, while keeping road speed down when moving - yet still retaining normal travel speeds.
The solution was twofold. First came the remarkable increase in engine power outputs, so a relatively small truck had the neccessary 50 to 60 bhp in reserve to power the sweeping services as well as moving along the road. The second development was hydrostatic drive, achieved by fitting a hydraulic pump to the engine and a motor on the drive shaft. While sweeping the Scarab becomes an automatic, with forward-reverse shuttle lever and speed from 0-30km/h controlled by the accelerator. For travel, the Scarab hydrostatic drive is disengaged and the vehicle is driven in the normal manner.
While most contractors now accept hydrostatic drive, as fitted to telescopic handlers, fork trucks, dozers and most compact sweepers, the fact remains that it does cost more. So five years ago Scarab came up with Unidrive, which is based on a 13t to 19t chassis with normal gearbox and fitted with a camshaft-driven hydraulic pump to drive the sweeping services. It competes head to head on price with the twin-engined sweeper, which also rely on the normal chassis gearbox for sweep speed control.
The demonstrator Magnum on a DAF LF55 chassis made its Northern Ireland debut at IWM Newcastle in April, and I was able to try it next day.
It`s an impressive machine when opened up, with a 6.5m3 payload volume in its stainless steel hopper and an 1800 litre water tank against the 1250 litre of a typical twin-engined sweeper which looses hopper space to accommodates its auxiliary engine and fuel tank - not to mention loosing an extra tonne of payload.
Unidrive components are the same as those on the hydrostatic machine, as are features such as steel pipes to replace rubber hoses, manual over-ride on control valves and steel rather than cast suction nozzle boxes. I liked the automatic fan wash which comes with the optional high pressure lance, otherwise it`s fairly easy access above the tailgate.
Some machines induce dislike from first acquaintance, some improve with experience, a few feel just right. For me the Magnum falls into the third category, due to the brilliant DAF LF chassis. Any driver will love the DAF for its low noise, smoothness and cab comforts, while its nine-speed gearbox, light controls and excellent lock make it an ideal basis for sweepers.
"Just use crawler gear and take your time", said demonstrator Tony Lawrence, "and you`ll find it`s easy". And he was right.
The cruise control is used to set engine speed to about 1000 rpm. Switching on the fan and imposing its 45 bhp load makes no difference to engine speed or noise, such are the wonders of electronic diesel control. With 180 bhp available the DAF isn`t even trying, and letting out the clutch in crawler gear produces effortless progress at 1.6 mph.
With both side brushes and centre brush extended the Magnum swept a 3.2m path around a long neglected car park with many loose stones. The surface was left spotless, leaving only a light stain where cement powder had been scatterd on oil spillages. Even this disapeared when the optional high-pressure front water jets were selected, the powerful suction leaving the surface almost dry. On lighter work the machine will sweep happily in fourth gear and full width.
The wander hose is equally impressive, bricks and rocks being lifted from several inches away and light material from up to a metre. In fact the suction is so strong that the fan speed must be reduced slightly to prevent the hose locking onto the ground.
Like most people, I expected a cost advantage from using red diesel for an auxiliary engine rather than the all too expensive white required by the motive power. But because the Scarab has only one engine working in its most efficient torque band it uses less fuel than a twin-engined sweeper with one idling and its auxiliary working hard, doubling friction and thermal losses. In fact the Scarab uses as much as one-third less, according to tests carried out by the Paris municipality.
Mr Lawrence says the Magnum is hard pressed to use eight litres per hour on the heaviest work, which compares with up to 12 litres for a typical auxiliary engine alone and easily cancels out the `red` cost advantage. The Scarab produces lower emmisions and makes less noise, of growing importance as contractors move to the enviromental standard ISO14002. And there is only one engine to fuel and maintain.
The DAF engine is very quiet, like those on all modern trucks. An auxiliary engine produces more noise particularly for the driver, which I find very tiring whether it`s a sweeper or a fridge rumbling away behind my head. And the public is becoming less tolerant of noisy machinery.
The Magnum Unidrive has to be a strong contender for the price-conscious contractor who wants to stay with a manual gearbox yet enjoy the Scarab economy and enviromental benefits. However for following a planer or municipal work the extra cost of Scarab`s hydrostatic drive would be well justified.