Johnston sweeps in with truck-mounted model
Johnston Sweepers' latest VT550 model has a payload of more than 2 tonnes and only requires a standard driving licenceJohnston Sweepers has launched a new truck-mounted sweeper which can be driven with a standard driving licence. The Johnston VT550 has been developed on the back of demand for a large-bodied, truck-mounted sweeper with a payload of at least 2 tonnes and which could be driven in the UK on a standard licence.
The resulting model is a 7.5 tonne truck-mounted sweeper with a 5.5m3 hopper, which sits between Johnston's CX400 mid-sized machine and its other truck-mounted V Range sweepers, and which has a genuine payload of more than 2 tonnes.
Designed primarily for municipal use, the VT550 is ideal for street and channel sweeping and can be driven on a standard licence by those who passed their tests before 1997 - which is a significant factor in driver recruitment.
The launch of the machine marks the culmination of a two-year engineering programme which set Johnston designers some tough challenges, the most significant of which was to achieve the 2 tonne payload.
Johnston's engineering director Clive Offley explains the design difficulties. "The lightest available truck chassis is 3 tonnes before we start, and the body and sweep gear on our current V range weighs just under 4 tonnes, leaving just half a tonne for payload," he says.
"The challenge was to take 1.5 tonnes out of the V range weight, without impeding the design integrity in terms of durability, reliability and performance."
The challenge was met through some design ideas to reduce the weight of most major components.
Firstly, alternative materials were sourced for the fuel tanks, which are now produced in rotaformed polypropylene, and for the cowl access door, which now uses vacuum-forged ABS plastic. The body itself is a new design in stainless steel with integral water tanks, which further reduces weight by optimising the function of every piece of steel used.
The control systems have also been redesigned, largely using pneumatics to control the sweep gear on the basis that aluminium cylinders filled with air are somewhat lighter than steel ones filled with hydraulic oil. The only hydraulics used on the new machine are for tipping the body and opening the rear door.
The search for lighter components even went as far as taking the copper out of the wiring looms. And now the sweeping functions of the machine are controlled by Johnston's CANbus JPlex display system.
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