To most people, street sweepers are little more than rotating brushes on the end of a motor-driven shaft. In truth, however, there is far more to these innovative little vehicles than meets the eye.
For instance, Stock Sweepers is taking the technology to new levels by launching a hydrogen-injection system for the auxiliary engine on its road sweepers. The system introduces hydrogen gas – which it generates on-demand using nothing but distilled water – into the air intake of the auxiliary engine.
This makes the diesel fuel burn much quicker, which helps reduce emissions to an all-time low and increase fuel efficiency by up to 30%. The upgrade is believed to be the world’s first use of hydrogen on-demand technology on production road sweepers, and is available on any of Stock’s new-build road sweeping vehicles.
The system sees autonomous electrolysers, developed in collaboration with Water Fuel Engineering (WFE) of Yorkshire, fitted to the auxiliary engine (which powers the vehicle’s brushes and vacuum). It was produced following seven years of development supported by the European Union and the University of Sheffield. Although Euro 6 automotive engines have been compulsory on new vehicles since 2014, auxiliary engines have been known to be heavy polluters, and been allowed to operate without the same levels of legislation.
The WFE HydroGen 3.1 electrolyser works synergistically within the conventional diesel engine, to introduce oxy-hydrogen gas into the combustion chamber. There is no need to refuel with hydrogen, as the electrolyser delivers oxy-hydrogen on the go and on-demand. The richness of the mix reduces fuel consumption by a minimum of 15%, and emissions by as much as 80%.
Stock Sweepers and WFE are now collaborating on the introduction of an electrolyser on the main Euro 6 engine too. The Office for Low Emission Vehicles has invited the two companies to put forward a proposal that will deliver ultra-low emission levels to enable 2020 targets to be met, or even exceeded.
Standing out from the herd
Clearly, the need for market differentiation is crucial in a segment where demand remains high. Vehicles that can demonstrate genuine gains for customers are sure to secure orders; at least, that is the experience of FAUN Zoeller, which has recently sold a pair of Viajet 6 sweepers with ‘Dual Sweep’ option mounted on DAF LF 16,000kg chassis to Fylde Borough Council in Lancashire.
FAUN Zoeller consulted with Fylde Borough Council over many months during the procurement process, taking care to ensure the delivery of a tailored solution. There was particular emphasis on operational capabilities, with feedback given directly by operators.
A detailed specification was put together, discussed with the drivers, and then demonstrated. The latter was essential as the council’s existing equipment lacked durability – the coastal routes in Fylde tend to collect a lot of sand. In addition, the council required the system for other functions, such as road clearances after traffic incidents.
After a successful demo, FAUN Zoeller received the order. The specification includes a complete stainless steel hopper, an uprated fan, John Deere auxiliary engine, pneumatic wander hose and a high-pressure system that incorporates the extended package with water jet bars to the channel and roller brushes.
Of course, it’s not just councils driving demand for the latest in street sweeping technologies. A case in point can be seen at Countyclean, an environmental service company from East Sussex which recently ordered a Merlin and a Magnum Plus Titanium from Scarab.
The latter is the company’s flagship sweeper and is suitable for civil works and specialist applications including airport runway and aprons, milling work, high pressure surface cleaning and glycol removal. It can be mounted on a chassis of choice in the range of 18 to 19 tonnes, which can be combined with Scarab’s hydrostatic drive system and its CANbus control and diagnostics system.
The specification can be enhanced further by Scarab’s Titanium options. These include a 2.5m full-width suction nozzle system mounted to the rear of the vehicle coupled with high-pressure water systems. Additionally, a fully articulating spray bar can be controlled from within the cab to slew left and right, as well as up and down.
Many brush options are available including front brushes for sweeping or weed-ripping, as well as an optional auxiliary channel brush with extended reach.
Further high-profile takers of this type of technology are airports. Indeed, Heathrow Airport has recently added a batch of six new Swingo 200+ sweepers from Aebi Schmidt to its service equipment fleet. It is the third Swingo order from Heathrow.
Debris collected by the Swingo 200+, which has a speed of up to 50kmph, is conveyed by two or three disc brushes to the suction nozzle before ending up in a large 2m³ hopper. The sweeping process takes place in connection with circulating water, which combines with the debris. In this case, a resource-saving pressurised water recirculation system with water separation and recovery can be used which also ensures that only clean and low-dust air is released into the environment. The low-emission EuroMot 3B or Euro 6 diesel engine with particle filter and urea injection further contribute to environmental balance.
New to the market
So, what of truck-mounted sweepers?
Well, among the latest market entrants is the VT (vehicle mounted twin engine) model from Johnston Sweepers. Being independent of the truck chassis, the axillary engine powers the sweeping functions and vacuum system, so both engine and chassis can be tailored to the application. A range of chassis can be supplied with either manual gearboxes, automatic Alison 3000 series gearboxes or 12-speed automated gearboxes. Auxiliary engines come in 55 or 93kW to tier 4 final/stage3b standards, or 85kW to stage 3a standard.
Once set to an operating performance, the twin engine sweeper system will perform at the same level regardless of gradient and travel speed. Furthermore, the sweeping operation can be paused or stopped and sweep gear lifted to allow the driver to transit from one location to another without having to disengage a separate drive.
Although the high torque 55kW engine is more than capable of sweeping road chippings, heavy detritus and planings, the 85 and 93kW variants provide additional power and speed when simultaneously sweeping and/or full-width nozzles are required.
Twin engines can be adjusted from 1,200rpm, suitable for light city sweeping, to 2,000rpm for maximum suction performance. What’s more, the auxiliary engine can be supplied with its own fuel tank, allowing tax-free diesel to be used where applicable and to carry additional fuel for longer on station time. Fuel consumption is said to be as low as 5.8l/h combined for both chassis and axillary engines.
In another development from Johnston Sweepers, the company has teamed up with Iveco to design and develop a new generation of road sweeper chassis for the UK market. The launch model was a New Eurocargo 150E25K chassis, built on a 3690mm wheelbase and featuring a 12-speed EuroTronic gearbox, manufactured by ZF. However, the New Eurocargo sweeper chassis is offered in 7.5, 12, 15 and 18-tonne models.
“The low-speed environment and frequent stop/start nature of sweeper work is a perfect match for our HI-SCR technology,” says Martin Flach, product director at Iveco. “We are confident that sweeper operators will recognise the advantages of a Euro 6 solution, which avoids the need for forced regeneration.”