TIPPERS AND TANKERS
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si Angus Spooner, General Trailer's tipper manager, warns bulk operators to be careful when upgrading existing tippers to 44 tonnes. "We have produced 9.5m, 10m, 10.5m and 11rn length tippers over the last six years, but only the 10.5m and urn tippers have long enough wheelbases to meet the 8m criteria," he says. Spooner points out that for low density products the 43.6m3 body that is standard across much of the bulk industry will have to increase to at least 46.6m3 to make full use of the available payload.
Operating at 44 tonnes when the traffic demands it and at 40 tonnes the rest of the time might seem an ideal solution, but it is fraught with difficulties. The problem is the impact the legal dimensions have on getting the weight distribution correct for both 2+3 combinations at 40 tonnes and 3+3 combinations at 44 tonnes. The risk is accidental overload of either the tractor drive axle or the trailer bogie.
The maximum permitted kingpin to centre-of-last axle dimension for 44-tonne operation is 8,135m, but any trailer measuring at least 8m has to comply with turning circle rules. So, if your trailers are 7.7m or 7,8m wheelbase (as many trailers currently in service are) they should, in theory, comply. However, the longer the trailer measurement, the better the weight tolerance, which is why trailer wheelbases of 8.2m and 8.3m are being recommended for operation at 44 tonnes.
But Ray Cattley, Volvo's legislation and environmental manager, believes existing trailers might be better used at 42 or 43 tonnes. "It eliminates any risk of overloading the trailer bogie," he points out.
Operations
Weight distribution is also an issue if long-wheelbase trailers specified for 44-tonne operations are hooked up to two-axle tractors for 4o-tonne trips. "The longer the wheelbase the more weight is imposed through the kingpin," points out Ian McGilloway of Renault. "Not all 4x2 tractors can accommodate the pin load," Trailer strength is also an issue.
Hyva believes dog-house-mounted tipping gears such as its FE183 will be most popular for higher weight tippers because they reduce the gap between tractor and trailer, thus transferring weight onto the tractor drive axle. However, the company warns that not all tipping rams are capable of handling the higher forces when tipping 44 tonnes. The larger bore rams need more oil to reach full stroke, and there are concerns that not all current wet kits on tractors have the four to five-gallon oil reservoir required.
Some tankers will need stretching, but maximising payload at 44 tonnes is relatively simple, say the tanker manufacturers, because operators know exactly how much space each litre of a particular liquid takes.
Renault's Ian MaGilloway says Hazchem operators need to check that their tractors meet the tougher ADR rules on braking performance for 44-tonne operation.
Many trailers built in the past five years may be designed for 44tonne operation but some have also been built to maximise payload at 40 tonnes. Chris Curzon, marketing director at Montracon, warns that some could suffer fatigue problems early than usual;
Some trailer chassis under 6.5 tonnes just aren't designed to cope with the extra stresses imposed from the extra three tonnes weight." The company's 44-tonne curtainsider design weighs 6.8 tonnes, and more steel has been incorporated in the neck and in the rear cross-members.
A new design of 44-tonne trailer was one of the first results of the new partnership between Krone and Southfields Coachworks. Krone continues to sell complete trailers in the UK but it is also supplying Southfields with chassis.
Distribution
One of the first 44-tonne trailers Southfields has produced is a Safeloada for distribution company Ferg-usons, which is putting 20 into service on a British Gypsum contract. The Safeloada combines Southfields' Urbanloada bodywork with Krone's Safeliner spaceframe chassis.
In place of the conventional I-beams ladder construction the Safeliner has two horizontal 16omm-high sections at each side, connected with vertical cross
beams. The top of the side sections are level with the floor platform and the bottom is 280/11M above the road. This design is claimed to save weight, as well as offering greater strength and impact-resistance.
The rear of the trailer is enclosed; the design creates series of aluminium-alloy co partments which provide a s ondary floor between the by edges of the space frame. Acct to the compartments is via g strut hinged doors, which can locked for extra security.
Double-deck sales have been steadily increasing and are likely to be helped by the weight increase to 44 tonnes. Montracon, for example, expects to sell more double-deckers in 2001 than in the past four years together.
Moving decks cost upwards of £30,0011 Trailer manufacturers have begun to develop double-decking systems that keep the cost down for general haulage work and maintain flexibility to carry a wide range of load sizes. Swivel decks have been around for some years and are popular with groupage operators as they permit mixed loads.
The Ratchet deck is a mechanically lifted adjustable deck from Don-Bur which costs about £8,000. Up to four 3Jm decks can be fitted in a 13.6m trailer; each deck has a three-tonne payload and weighs 800kg. The deck is lifted with a fork-lift truck and has retractable lugs which engage in side pillars as the deck is raised.
The Schmitz double-deck trailer comprises a Flexes curtain-sided body with steel corner posts for additional strength. The operator locates aluminium beams between each pair of sliding side posts to create the second deck. Five posts each side are needed to ensure the cross-beam pitch is close enough to support the maximum number of Euro pallets on the second deck. The height of the beams can be adjusted to suit the load. Each cross-beam can carry 160kg, with a maximum top-deck capacity of 13 tonnes.
Deck length can be adjusted and mixed-height loads can be accommodated. The extra weight of the double-deck system is 840kg, including the steel corner posts. The cross-beams can be stowed anywhere convenient on the vehicle, including in the pallet box or roof For payloadcritical trips when the double-deck system is not needed they can be removed and left in the depot