With people being increasingly concerned about the impact that air pollution has on health and the urban environment, Rodger Hoadley, founder and Managing Director of Scarab Sweepers Ltd, is convinced that environmental legislation is set to favour `single engined` sweepers.
"It is not enough to produce something at a low price with satisfactory cleaning performance," he says "it must also be clean. This is the principle on which all our sweeper ranges have been designed, and our new machine, the Scarab Monic, is no exception."

A Key report published in January 1998 by the independent expert committe on the Medical Effects of Air Pollutants (COMEAP) for the Department of Health was the first official attempt to quantify the impact of short term pollution on the health of people living in the UK. It suggested that the deaths of between 12,000 and 24,000 vunerable people may be brought forward each year and that between 14,000 and 24,000 hospital admissions and re-admissions may also result from poor air quality. According to the report, these effects are attributed to three of the eight pollutants for which objectives have been set in the National Air Quality Strategy: Particulate Matter (PM10) - which is estimated to bring forward 8,100 deaths annualy; sulphur dioxide - 3,500 deaths, and ozone - from 700 to 12,500 deaths.

Burning fuel creates pollution and Rodger believes that the effective subsidy of rebated red fuel for the auxiliary second engine on road sweepers will surely become an area for investigation in the future by the UK Goverment, particuarly if the income could be `ring fenced` to finance solutions for environmental issues elsewhere.

"The single engined sweeper can save 10,000 litres of fuel a year. I don`t believe that operators will tolerate the significant price rise if they have to use road priced fuel in both engines," he comments "And this is before the pollution that 10,000 litres of fuel creates is taken in to account."

With regard to the development of alternatives to "Twin engined" sweepers, Rodger believes that Scarab have made a significant contribution. "Any road suction sweeper requires engine power for propulsion, for their brushes and fans. Machines of the 1960s had mechanical drive from the prop shaft. When the vehicle stopped so did the fan, and it took several seconds to spin up to speed again, with a long uncleaned stip left each time the vehicle moved off as a result.

"Powering the brushes and the fan required some 50-60bhp and lorry engines of this era did not have this much power to spare. The industry found the optimum solution at the time was a second, smaller engine to power the brushes and fan, and during the time I spent working with Blaw Knox, there were half a dozen makes of sweeper, all using the twin engine arrangement."

Rodgers argument know however, is that with the major enhancement of engine efficiency available today, even a small lorry has enough power for sweeping services taken from the chassis engine. Back in the mid-70s, however, when Rodger established Scarab, he tackled the problem from another direction, using all in-house designed hydrostatic drive to move the vehicle at low speeds so that the truck engine rpm could be maintained for fan & brushes; between sites, the hydrostatic drive is disengaged and the truck drive in the normal way. More recently came the Scarab Maxim, which uses normal clutch and gearbox for travel, as would a twin engined sweeper, and a mechanical PTO for the fan, instead of a second engine, thereby still adhering to the single engine principle.

The company have now taken another step forward in `single engine` technology with their latest hydrostatic drive machine, the Scarab Monic, which has been designed to offer widely variable road speeds for city work. Initial development has been based on, an Isuzu chassis-cab which is only 2m wide, saving 200mm over most 7.5 tonners. The engine drives a pump which supplies sweeper services and the hydraulic motor which replaces the gearbox and clutch.

"I am convinced that the Euro 2 requirement will present twin engine sweeper manufacturers with difficulties" , says Rodger, advantages for Scarabs Single Engined sweepers including around one tonne greater payload, and more space in the hopper, because the donkey engine, cooling system or extra diesel tank has been eliminated."

"At Scarab we feel that our philosophy translates directly the task that the Goverment has set manufacturers to ensure that vehicles are more fuel efficient, less polluting, quiter and less resource intensive."

"With exhaust emmisions being the predominant source of air pollutants from road transport and with the main thrust of measures being to improve exhaust emission performance of new vehicles, it is suprising that the principle of auxiliary engines has remained for so long. This is partly as a result of the mandatory vehicle emissions being applied in principle only to the chassis and not the total vehicle operation.

"At the end of the day, it is unavoidable fact that the majority of road sweepers have a clear impact on local urban air quality as their operating pattern is focussed in towns and cities. The increasing emphasis on reducing pollution due to exhaust emissions is an issue which which this sector cannot, therefore afford to ignore in the future."