PRODOCT ROONDOP There's been a flurry of activity in the
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trailer sector recently: Fruehauf, SDC and York all have new owners. And the dry freight trailer market is buzzing with material and design innovations... CM looks at the highlights.
It's been a case of chequebooks at dawn in the trailer sector. SDC has been bought by Powerscreen International, a Northern Ireland-based construction and quarrying equipment group (which also owns Moffett Engineering, best-known for Mounty truckmounted forklift trucks).
Fruehauf's parent, French-based Societe Europeenne de Semi-Remorques, has been sold to Littlejohn and Co; an American investment group. And Wordsworth Holdings, owners of York Trailers since 1991, has teamed up with American trailer builder Utility to set up Utility International which builds trailers at York's Northallerton plant.
4. TRAILER CHASSIS
Owners may change but one key issue always remains—saving weight without compromising durability Operators now rely on trailer manufacturers to preserve payloads, especially in the face of higher tractor weights. High-tensile steels and computer-aided design are the main weapons in the weight war.
Darlington-based Tinsley Trailers, for example, and its parent British Steel, collected data on 14 dynamic loadings on a trailer chassis, including running over potholes and hitting kerbs, while developing a new all-steel trailer chassis, which weighs just 4.95 tonnes. Changes include thicker (510mm) main rails with thinner (8mm) flanges. More than 50 are now in service, says Tinsley.
York, as it was then, used similar computer design techniques on its ZT chassis, cutting a typical curtainsider weight from nearly 7.0 tonnes to 6.1 tonnes. Savings include 100Icg on a redesigned fifth-wheel rubbing plate.
Manufacturers have been making big efforts to reduce the weight while improving the durability of trailer floors and some are prepared to back their claims with longer warranties. Southfields, for example, now guarantees some floors for five years. Typical measures included closer-pitched rear crossbearers to reduce point loadings from fork-lift trucks, and aluminium to save weight.
• CURTAINSIDERS
Abolition of border controls within the European Union has led continental operators to realise what British hauliers have appreciated for years: when it comes to speed and flexibility of loading, a curtainsider beats a TIR tilt body hands-down.
Curtainsider specifications can be tailored to suit operations (Fruehauf, for example, offers 30 variations on its Speedliner). Angled front corner pillars, recessed rear door locks and hinges provide enough interior length to carry 34 pallets; wrap-round curtains maximise side aperture width; and concertinastyle roofs remove aperture-height restrictions on loading and also allow goods to be loaded through the roof.
UK manufacturers can get close to or below the magic 6.0-tonne figure without resorting to aluminium in the chassis or superstructure.
Don-Bur won Commercial Motor's 1997 Dry Freight Trailer of the Year Award for its Palletmaster 2001 curtainsider. The standard Palletmaster has an all-steel chassis, bolted galvanised steel superstructure and an aluminium roof. It weighs 6.2 tonnes, but aluminium sideguards and air tanks reduce this to around 6.0 tonnes. Don Bur is confident that 5.5 tonnes is possible with more aluminium components.
The Palletmaster reflects the vogue for allbolted curtainsiders. They are supposedly easier to repair than welded ones, but Cartwright and Montracon are among those who argue that welded frames are stronger and better able to resist twisting stresses. Lawrence David, which pioneered bolted construction on its Traccess curtainsider, says it solves this problem by mounting its bodies on neoprene rubber blocks that spread the stresses.
Southfields' Elite curtainskier combines the two methods. It has a welded front bulkhead buttress for strength and bolted rear frame for easy repair.
Galvanised steel frames and anodised aluminium bulkheads, also pioneered by Lawrence David, are now widely available. They prevent rust spots and do not have to be painted.
Prestressed cant rails, whether steel or aluminium, are widely used to eliminate sagging turfs. The rail is bowed, not straight, Sc) it resists the downward force exerted on it when curtains are tensioned.
Lawrence David's Traccess is the only curtainsider with unobstructed side access. All its rivals have one or more posts each side to support the roof, usually moveable to improve access.
The roof can drop when the side post is released, making repositioning difficult. Boalloy's solution is a pivoting post that swings clear of the side and can be moved a limited distance along a channel under the side rave while still supporting the roof.
Cartwright and Grahams make similar captive posts, but the one on Fruehauf's Speedliner post literally goes further: it has a hinged rear section at the bottom that stays permanently located in a full-length side-rave channel even when the post is pulled outwards to slide it along.
Montracon's Speedtrack and Cartwright's Easy Glide are designed to cure the problem of rollers jamming against one side of the curtain track which makes opening and closing curtains hard work, especially in wind. Locating curtain poles correctly can also be tricky. Fruehauf's Speedliner curtainsider has a clever hinged top-corner capping combined with a profiled aluminium channel to guide the pole into its correct position.
Instead of buckles, the curtain on Don-Bur's Palletmaster 2002 body has a tensioning system that tightens all the straps at once. Each strap has a hook and roller at the end. The hook is pushed over a cable running behind the side rave and supported on nylon rollers. A ratchet under the rave shortens the cable, tightening all the curtain straps at the same time with equal tension.
DOUBLE-DECKERS
Improved reliability of lifting floors is boosting sales of double-deck trailers, say the manufacturers. Lifting floors offer the potential for faster, more flexible loading than fixed decks and floor heights can be varied to suit the load.
Cartwright and Ray Smith are experienced in hydraulics for demountable-body operations. Both use hydraulic rams in their lifting decks, one in each corner. Cartwright uses flow dividers to ensure the floor stays level; Ray Smith uses electronic sensors in each of its rams to ensure they all move at the same speed, irrespective of load.
Don-Bur and Wilson Double-Deck Trailers both use cables to support the second deck, with lifting and lowering handled by a single hydraulic ram mounted in the deck itself. Because one ram is used for all cables, the deck movement is equalised whatever the load distribution.
An upper deck that swivels into a vertical position forming a centre longitudinal bulkhead is popular with some hauliers, reports Grahams. Light, bulky loads can be carried on one trip, and pallets for a return load.
• DRAWBARS
EU Directive 96/53 on vehicle dimensions, which is being incorporated into UK Construction and Use regulations, is likely to encourage shorter bodies with less demand for extendable drawbar couplings.
Until now, many UK operators have taken advantage of a UK derogation permitting bodies up to 8.1m up to an overall drawbar length of 18m. This combination is now outlawed and those already in service will only be allowed to operate until 2006. Although the EU has increased overall drawbar lengths from 18.35m to 18.75m, the maximum body length is 15.65m, and the maximum distance from the back of the cab to the rear of trailer, including the coupling gap, is 16.4m. There's no point using extendable couplings, because reducing the gap will not allow longer bodies.
Abel's Malcom Brown says 750mm is unlikely to be enough with maximum-length till bodies because of the risk of clashing on inclines.
• BOX VANS
Van trailers are benefiting from lighter chassis and detail changes aimed at reducing maintenance costs. Recessed top marker lamps and door hinges save repair bills, while waterproof junction boxes and preassembled wiring looms with plug-in connections have increased electrical reliability. Pneumatic connections are tidier, and bulkhead-mounted tractor-trailer connections are better protected against reversing damage.
o by Sharon Clancy