'Civilised' waste service
Page 17
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A joint West Sussex CC/Volvo exercise has succeeded in removing larger loads of British rubbish at a lower cost. By a special correspondent
TATISTICS show a steady rise .1 the amount of rubbish we irow away. The recession does ot make even a dent in the -aountain of waste produced. Local authorities burn, pulvese, shred, dump, bury and rocess it. They face increasing ommitments in terms of refuse isposal on the one hand and ghtening financial strictures on le other.
West Sussex County Council 3ced this problem at the end of ist year, by which time a key 'art of its bulk refuse vehicle eet had reached the point when :s reliability and performance ad fallen as low as 62 per cent vailability.
The council then opted for iremium spec vehicles for Teeter reliability and, after a .ehicle appraisal programme, lecided to buy two 6x4 and two lx4 Volvos.
To achieve maximum effiiency with the eight-wheelers, Vest Sussex's group engineer, vaste disposal, G. G. Russell, rnd principal engineer, John RoJerson, specified a 1 6-ton payload of the pulverised waste naterial. However, this material as a 0.26 tonnes per cubic netre density which meant a )ody of 60cm (80cuyd)l But such size body is impractical.
To avoid the necessity of tipaing, the council officers and (olvo engineers considered hoizontal discharge. This allows he use of a bigger body and a onger chassis. If the load is to )e discharged by a ram, thought he team, why not strengthen he back door and use the same am to compress the material to achieve greater payloads?
An artic 32-ton-gcw vehicle vith a 65cuyd body and compacion equipment was considered )ut its gross weight of over 18 ons gives a payload of only 14 ons.
Trials convinced the team that nany problems could be )vercome if the ejection ram :ould be used to compact the oad as well. Only a low corn)ression ratio of 35 per cent was .equired. So a specification was )roduced for a 5.6-metre chassis with a 26ft long 60cuyd body not o exceed 6 tons in weight, and :apable of increasing the density yf the refuse by 35 per cent. It
was specified that the body had to provide for a total payload of 30 tonnes should future legislation allow.
Volvo engineers, together with TTB (Fabrication) Ltd of Dartmouth, part of the Boughton Group, then got to work. TTB designed and produced the 46cuyd air-space body and ram equipment capable of dual operation, ejection and compression.
The resultant Volvo F7 8x4 vehicles, supplied by distributor Princes Commercials (Southampton) Ltd, are fitted with the Volvo TD7OF engine and 16speed range-change gearbox. The 5.6-metre chassis is fitted with heavy-duty-stack leaf suspension. The high-tensile steel body, 8.03 metres overall length, 3.038 metres high and 2.5 metres wide contains a six-stage single hydraulic self-supporting ram with a stroke of 6.096 metres.
The blade or platen, set at a vertical angle of 45°, is of an offset chevron shape, a configuration determined by trials to give maximum payload space and an extremely clean ejection.
Two separate hydraulic control operating stations are provided — the low-pressure compression controls are positioned on a catwalk above the cab to allow the operator a view inside the body and the highpressure ejection controls are mounted in the cab. The driver can slowly move the lorry forward during the ejection cycle.
Built-in microswitches cut out the controls should the doors not to be in the correct position. The heavy rear door is designed to withstand 14 tonnes force.
One of the 8x4s operates out of a refuse processing plant at Burgess Hill, making three or four round trips a day to the landfill site at Small Dole 15 miles away.
Loading beneath the overhead conveyor system takes around three quarters of an hour.
The second 8x4 with identical equipment operates out of the council's Littlehampton refuse amenity site and travels 15 miles to the council's landfill site at Sompting.
Different seasons produce different refuse — hedge and tree clippings in the autumn give a lower density of rubbish so Mr Russell is considering a slightly higher compression rate at these times to keep payloads up.
The 8x4s replace rigid and drawbar container vehicles, but the container system is retained for various operations and two new F7 6x4 rigids were pur chased to operate this system.
Containers are required at Burgess FILII to handle waste collected by private contractors and household items brought in by residents to special sites. But the containers have another advantage. When the 8x4 bulk refuse vehicles are not loading, the pulverised waste can be loaded into containers which act as buffer stores to give constant capacity at the pulverising plant.
The two 6 x 4s have the R62 eight-speed gearbox and heavyduty rear suspension. The 18m rigid and drawbar combination operates at 32.5 tonnes gross weight and is fitted with Multilift IVIL20 chain-lift equipment for lifting and dropping containers. A vehicle weight of 13.5 tonnes (including container) with its five tonnes drawbar trailer (and container) gives a payload of 14 tonnes.
In operation the drawbar trailer is disconnected at the tip's hardstanding and the rigid drives on to tip from its container. The vehicle then returns to the hardstanding, drops the empty body and takes on the full container from the drawbar trailer. It then goes to the tip again, empties the container and returns to the hardstanding. Here it replaces the container on the trailer, picks up its own empty Container and drives back to Burgess Hill.
The 6x4 rigid and drawbar outfits have been designed with future legislation in mind and West Sussex CC would hope for, say, an extra 4 tons payload bonus should plated weights go up to 36 tons for these vehicles.
For flexibility of operation and optimum performance, the 6x4 outfits operate with 18 containers and six drawbar trailers.
The new 8x4s, with the compression facility for greater loads, are saving the equivalent of two drawbar outfit trips to the tip every day.
Mr Russell is pleased with these initial results. "The indications are that the very modest increase in investment for the ram ejection is paying off with increased payloads and we should easily get our money back on the amount paid for the additional equipment in less than a year."