Looking over the horizon to new concepts in street sweeper design & engineering

Developments have thus far been largely driven by customer requirements and,

in recent years, by legislation,” explained Johnston Engineering’s Marketing

Manager Steve Douglas. “End-users are quite rightly demanding machines that

are simpler to operate and maintain, while delivering better performance

levels. Increasingly stringent European legislation has also resulted in

manufacturers concentrating development resource on reducing noise and

noxious emissions.”

Optimum mix

“The 5000 Series represents the optimum mix of features and performance

levels demanded by today’s customers and legislators. Our challenge as we

move into the 21st Century is to build on engineering knowledge and

expertise acquired since 1904, and continue to offer machines which fulfil

tomorrow’s customer needs as well as today’s.”

Mike Sandford is Johnston Engineering’s Scientific Project Leader, and is,

therefore, at the forefront of new generation product development. “What

would have been considered ‘Blue Sky’ technology as recently as 10 years ago

is now commonplace. Some of today’s Blue Sky concepts will inevitably become

core product, as the end-user requirements of safety, environmental probity

and legislative compliance become increasingly important,” stated Mr

Sandford. “There are several projects in the embryonic stage, and we are

working together with third parties to develop concepts into working

prototypes.”

‘Intelligent Sweepgear’

One development under research in conjunction with prominent Research

Institutions is that of ‘Intelligent Sweepgear’. Mr Sandford explained, “The

sweeping equipment could have sensors fitted which detect the size, bulk and

mass of material to be ingested. Once identified, engine speed, brush speed

and tilt, nozzle gap and water spray pressure would adjust automatically,

according to the needs of the immediate environment. Not only does this have

implications for efficient use of water and fuel, minimised emissions,

minimised wear and tear on the engine and sweepgear but perhaps the most

important benefits of such systems are the implications for the operator, as

he does not have to concentrate so much on material pickup.

“This increases safety and a major contributor to driver fatigue is

eliminated. Other benefits could be realised in lower overall noise

emissions and increased vehicle longevity.”

Microprocessor

As part of this ongoing research which focuses on man-machine interface,

voice activated microprocessor technology is being investigated as a

feasible alternative to joysticks and conventional control panels.

Other developments involve new engine technology, currently being pioneered

by major engine manufacturers.

Much development has already been undertaken to improve electronically

controlled engines, incorporating innovations such as pre-programmed

constant engine speeds and failsafe systems.

Mr Sandford continued, “Electronic feedback on the throttle control would

enable the engine speed to change according to the load demand, optimising

operational efficiency and fuel economy. Failsafe systems operated

electronically will incorporate a self diagnostic feature which will shut

down cylinders should a failure occur, allowing the engine to run on other

cylinders until the end of the shift. Using this ‘cycling’ technique, the

operator will be able to finish the job before having to diagnose the

failure.”

This not only allows continued productivity and minimal downtime as the

machine is capable of staying on the road, but running at constant speeds

minimises engine wear and tear, and gives consistent and economic fuel

consumption levels.

Fuels & emissions

No future technology focus would be complete without talking about fuels and

emissions. “We remain well below Euro legislation limits, and are working

together with engine manufacturers to ensure that total emissions are

continually driven down,” said Steve Douglas.

Hydraulics and fuel concepts

“We are also currently looking at other concepts for further development,

such as water hydraulics and alternative fuels for both chassis and

auxiliary engines. These include gas and electricity, although it is

possible that a hybrid (diesel-electric) engine will emerge before a fully

electrically powered engine,” concluded Mr Douglas.

End-user priority

These represent only some of the very real concepts which the largest

sweeper manufacturer in the UK is developing. But, concluded Mr Douglas, it

is still the end- user who remains the priority at Johnston. “All of these

ideas will enhance our ability to provide the tools to enable our customers

to run their businesses more productively and efficiently, which has always

been our aim. We are looking at the next generation of technologies to help

them do just that.”