A road sweeper is always a welcome sight in one's neighbourhood and driving one is - undeservedly - one of society's less respected jobs. An hour trying to get to grips with one of Johnston's smaller sweepers showed me that they are not an easily operated piece of plant - reports David Stokes.
Irecently had the pleasure of trying out the Johnston Compact 50, a small sweeper in the scheme of things but nonetheless daunting on one's first outing. When you sit in the cab the array of levers, switches, knobs and pedals can initially leave you flummoxed. It's clear that with years of development behind it the modern mechanical road sweeper has grown into a very complex piece of machinery indeed.
Two levers just in front of the handbrake lever operate the two 'out front' 850mm brushes - their speed is variable and they are capable of rotating from 0 - 125 rpm. Their job is to gather up the dirt into the range of the suction box. If the machine encounters drink cans, large leaves and bottles, you can enlarge the intake of the suction box at the press of a switch, but the power of the suction is less.
Visibility for the driver is important and Johnston is very much aware of this; the test machine had door mirrors each side and two mirrors at the top of the screen so the driver had a good view of the brushes. Facing rearwards is a CCTV camera, so backing up to cars, skips etc. is easy.
The driver virtually has eyes in the back of his head - an important feature especially when school is out. Schoolchildren - being what they are - find this tiny road sweeper a magnet. It seems unthreatening, it's a neat piece of machinery and to the bored school kid it's something to climb on to the rear bumper and get a free ride. The CCTV camera will at least tell the driver that there is a stowaway.
A multifunctional vehicle
The Compact 50 bristles with accessories. To shift difficult bits of 'stuck-on- grot' there is a high-pressure lance the driver can use. Just open a door on the nearside, pull out the lance (which is on a hose reel) switch on the pump and direct the spray. Street furniture can mean that rubbish may be out-ofreach for the Compact 50 - but for that refuse rblown about behind telephone kiosks and cabinets the operator can clear it away using the 'wanderhose.' It's 4” hose with a 3.5 metrereach.
It's located on the roof of the Compact 50; it is in effect a giant vacuum cleaner hose and this can clean up where the sweeper can't. On each side of the sweeper are saddle water tanks with a combined capacity of 157 litres. This is the 'lost' water that plays on to the brushes and, when empty, has to be filled at a hydrant.
Inside the rear of the vehicle is a 250-litre tank for the recirculating water that mixes with the dust as it enters the machine - this is filtered out into the hopper and reused.
Power is provided with a seemingly over large 2.7 litre diesel, however, when you take into consideration the many hydraulic motors and other systems it has to drive then it doesn't seem so extravagant. The VM Detroit 494 HT3 engine combines the excellent capabilities of high torque with low revs, which equates to low noise and low engine component wear.
What it feels like
You need to be as mentally and physically agile as a helicopter pilot when driving one of these machines. You need to have your wits about you when driving the Compact 50. Unlike larger machines where the brushes are static in relation to the vehicle, the Compact's brushes have the ability to be swung from side to side.
On a straight road - say - you steer the vehicle whilst keeping an eye to the front and the rear using the CCTV screen and the many mirrors as well as 'steering' the brush into the kerb and compensating for its irregularities AND being careful not to be accused of 'you-missed-a-bit'!
I have to say that I have a lot of respect for those under paid and under valued group of people who drive these vehicles because, it's a difficult job made harder with parked cars, poorly-designed and maintained roads and litter louts.