Custom manifolds help Scarab clean up

A compact, lightweight aluminium manifold block developed for Scarab Sweepers allows all the company's machines' sweeping and tipping functions to be hydraulically controlled.

Since 1979, Scarab Sweepers has been helping to clean up the environment.

From compact Minor to the massive 7.5m3 capacity Mistral and Magnum models, Scarab's street sweepers have become a familiar feature of our urban environment handling the thousands of tons of discarded fast food wrappers, plastic cups and all the other evidence of our consumer society.

But, unlike many sweepers, Scarabs are themselves designed to be environmentally friendly.

Sweepers used to be built by mounting a self contained sweeper body onto a conventional truck chassis.

The vehicle was propelled by the truck engine and transmission, and the sweeper's main suction fan, main sweeping brush, side brushes and tipping gear were operated by a second auxiliary engine.

But Rodger Hoadley, Scarab's founder and Managing Director changed all that.

Hoadley knew that it would be far more cost effective - and environmentally cleaner - to do away with the donkey engine, saving weight and releasing valuable extra capacity for the hopper and water tank.

The problem was how to drive all that sweeper equipment and the vehicle with a single engine.

The answer was relatively simple: to add a transfer box into the driveline, and use the engine to drive a hydraulic pump and thus generate the required hydraulic power.

Thus the Scarab hydrostatic drive was created.

With the hydrostatic drive disconnected, Scarab vehicles can travel at speed between jobs, or to and from waste sites.

Only when the hydrostatic drive is engaged is power provided to drive the vehicle, the suction fan, the brushes and spray systems.

The result is a range of lightweight sweepers with the highest payload per gross vehicle weight, lowest fuel consumption and lowest exhaust emissions currently available.

As Hoadley puts it: "As far as the environment is concerned, one engine is always cleaner than two".

The key to Scarab's success is hydraulics.

For more than ten years Scarab has worked closely with Hallmark Hydraulics a local distributor and Sterling Hydraulics' design centre.

Sterling Hydraulics is a world leader in the design and manufacture of screw-in hydraulic cartridge valves and custom manifold blocks.

Sterling Hydraulics has built a reputation for working closely with its customers to find the best solutions for their specific hydraulic requirements, and Sales and Marketing Director David Symes is clearly delighted with his company's relationship with the market leader in sweeping vehicles.

"Space and weight are two of the biggest challenges facing vehicles designers", explains Symes.

"Perhaps the most difficult task is fitting all the components required into the available space - after all, the less the machine weighs the greater the payload it can carry or, alternatively, the smaller and less expensive the chassis".

"This is where Sterling Hydraulics can contribute most".

Sterling Hydraulics expertise is in the design and manufacture of compact custom manifold blocks which accept its range of common cavity screw-in cartridge valves.

The custom manifold block is a good example of how standard products can be used to create a cost effective solution to an hydraulic engineering problem.

The Sterling Hydraulics standard range of screw-in cartridge valves includes two and three position solenoid valves, pressure and flow control valves, check valves, diverter valves and shuttle valves as well as manual valves.

In fact all the components necessary to create complex control systems.

Connecting individual components together by hydraulic hoses is untidy, space consuming and prone to leaks because of the many joints involved.

The custom manifold block brings all the components together in a single block of steel or aluminium in which flow channels or galleries are machined.

The individual valves simply screw into precision engineered cavities and switch the flow of hydraulic fluid between the galleries.

The block has ports for connection to the hydraulic supply pump and to hydraulic motors, actuators and cylinders which have to be controlled.

The ports are machined to meet the size and thread requirements of individual customers.

It is the hydraulic equivalent of a printed circuit board.

For Scarab, Sterling Hydraulics designed a compact, lightweight aluminium manifold block which allows all of the machine's sweeping and tipping functions to be hydraulically controlled.

Scarab sweepers spend most of their working life on roads but have to travel to landfill and waste sites to discharge their payload.

"Many of these sites have poor access roads which leave hydraulics vulnerable to damage", says David Symes.

"Custom manifold blocks eliminate many hydraulic hoses and make the hydraulic system rugged".

"And screw-in valves make maintenance and repairs much quicker so Scarab vehicles spend more time on the road and less in the service bay".

The use of custom manifold blocks has allowed Scarab to design smaller machines that are more manoeuvrable - and that is important for pedestrianised areas to avoid inconvenience to the public - whilst providing a wide range of pushbutton controls that mean greater comfort and safety for the sweeper operator.

The reduced gross vehicle weight means not only lower fuel consumption, particularly when Scarab's single engine design is taken into account, but quieter vehicles - a real benefit for both the driver and the public.

The custom manifold block also reduces the potential leakage points for hydraulic fluid, as compared with conventional piping.

Leakage is always an inconvenience and, in the case of street sweepers, potentially a hazard, particularly if the sweepers were to lose oil in pedestrian areas.

So custom manifold blocks help to mitigate the health and safety risk to the public whilst providing improved environmental protection.

Sterling Hydraulics offers an hydraulic system design service from concept and development of the circuits to prototype and final production.

This, together with the company's comprehensive range of valves with working pressures up to 420bar and a choice of materials of construction, means that they can provide a very special tailor-made service.

"Our experience of working with Scarab has been mutually beneficial", says David Symes.

"We can offer price competitiveness, drawing on our considerable experience".

"And we are innovative - always prepared to look at new designs and concepts and able to develop special products if necessary".

"The end result means clean, modern, effective, efficient and acceptable street sweepers that lead the field".

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