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From the Drawing Boer

15th November 1980
Page 56
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Page 56, 15th November 1980 — From the Drawing Boer
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Which of the following most accurately describes the problem?

+IVEILED at MIRA a few weeks o by Transport Minister Nor3n Fowler, the safety artic3ted vehicle (SAV) is not so Jch a new design, rather an cumulation of all the safety iented concepts and devices lich have appeared in recent ars.

The outfit is the result of the mbined efforts of the UK hide and components industs along with the Department Industry and the Transport d Road Research Laboratory. le whole project was co-ordited by the Motor Industry Rearch Association, on whose emises the SAV was built.

At the SAV launch director of IRA Dr Cedric Ashley provided me background information to the reasons behind the pro:A by giving some statistics for :cidents involving heavy hides. For example in 1976, .4 people were killed in such cidents, which meant that 13 ?..r cent of fatal accidents volved heavy vehicles. (But, as • Ashley pointed out, this also eant that 87 per cent of fatal cidents did not involve heavy )ods vehicles!) In this same 1976 study it was und that only 67 hgv drivers are killed, which indicates that

e protection of other road us-5 in collision with heavy ?hides is statistically of greater gnificance than the protection the lorry driver himself. Of ese 67 drivers, 31 had acci3nts where no other vehicle as involved and, of these, 22 ere rollovers.

In 31 accidents between hgv id hgv, the circu'rnstances were sually too violent for trengthening of the cab ructure to have made any sigficant difference. So it was felt at the primary safety requirelents, such as improved roll 'ability are important, and 3condary improvements, !rough the use of seat belts, for +(ample, could help signifi3ntly.

Dr Ashley mentioned that lere is a run-on effect, that is if nprovements in roll stability reuce the number of roll-over .3cidents, then the importance I seat belts to prevent ejection also reduced.

In accidents involving cars and heavy vehicles, nearly twothirds of frontal impacts were underrun cases and these totalled no less than 20 per cent of all accidents involving hgvs. Impacts into the rear of heavy commercial vehicles were also important, representing six per cent of casualties.

These statistics, according to Dr Ashley, emphasised the need for underrun protection, preferably with some form of absorbent structure.

The hardware

One of the main requirements for a tractive unit as far as safety is concerned is a combination of good handling, braking and ergonomics. The Roadtrain was chosen because it met these requirements though it was mentioned at the time that other UK vehicles also have similar characteristics.

The M&G tanker used for the SAV project is the low centre of gravity model made from double-skinned fibre reinforced polyester. It has a capacity of 30,000 litres (6,600 gal) made up from six individual inner tanks of 5,000 litres each which are separated from the external shell by a layer of rigid polyurethane foam. This foam is loadbearing and self-extinguishing in the event of fire.

The combined effect of the rectangular and low central body sections has been a considerable lowering of the centre of gravity compared with conventional tankers and this, combined with the air suspension, is claimed to reduce the likelihood of a vehicle roll-over accident.

The other trailer to be exhibited as part of the overall safety "package" is a Crane Fruehauf curtainsider, again fitted with air suspension. This features a Quinton Hazen underrun bumper as well as two side panels for cyclist safety. One of the side panels is from Mathweb, a subsidiary of BP, and uses a resin-impregnated plastic lattice.

Impact strength

The Mathweb guard consists of a grp lattice for impact strength covered with a grp sheet for a clean appearance and low wind resistance. The structure is about one quarter the weight of an equivalent unit manufactured from mild steel and is designed to withstand art impact of a 200kg 14cwt) weight at 18km/h {11mph) without breaking.

This is claimed to provide ample protection for pedestrians and cyclists and some protection for motorcyclists at low speeds.

In the case of heavier impacts great enough to rupture the panel, the Mathweb structure has been formulated to avoid the formation of sharp edges.

Aerodynamic devices for the front of curtainsiders are normally associated solely with fuel-saving but, by cleaning up the air flow along the side of the vehicle, they prevent the side curtains from billowing and thus preserve the driver's rear mirror view.

Also included in the overall safety specification for the Crane Fruehauf trailer, is a Spanset load retention system designed to meet the UK Code of Practice for the safety of vehicle loads and also the Hope Brake Wear Indicator which has a warning device visible in the rear-view mirror. This arrangement gets over the problem of finding yet another terminal on the electrical socket.

Both trailers and the Roadtrain are fitted with a tyre-pressure monitoring system developed by Lucas. Air is piped from the conventional tyre valve to a pressure switch mounted on the rim in the case of tubeless tyres. While the tyre pressure stays at the required level, this switch re mains closed but if the pressui falls the switch activates if warning system. The system on a failsafe basis in that, if fault occurs somewhere in if electronics, the display in if cab will indicate as much.

York is represented on tlSAV with its Safety Base fiftl wheel coupling designed to ii crease the roll stiffness of an a tic combination when cornerin and so improve the stabilit York claims that when cornerin with a conventional fifth-whee semi-trailer stability is reduce as the oscillation axis of if coupler remains at right-angle to the centre line of the tract( which allows the trailer to roll t a greater amount, being held i check by the tractive unit.

The Safety Base is designed 1 keep the oscillating axis of th fifth wheel at right angles to tltrailer, not the tractive unit, du ing cornering.

The fuel tank of the Roadtrai is coated with a fire-resistai epoxy coating developed by A( vanced Fireproofing Systerr Ltd. Known as FIREC, the sub: tance had been applied to tltank in a Smm (0.2inl layer wii the pipework being clad i preformed tubes. Though no mally left with an unfinished su face, the MEC on the Roadtrai tank has been smoothed dom, for reasons of appearance.

Brake improvements

Both trailers and the tractiN unit incorporate anti-lock bra ing systems, Dunlop Maxar, on the former and the Girlir Skidchek system on th Roadtrain. The choice of the bn, systems is to demonstrate the compatibility with one anothi so that any tractive unit ccouple to any trailer regardle; of the make of anti-lock fitter The Leyland also has a Cla, ton Dewandre Hydro-Air systei which is claimed to improve if actuator response. This syster consists of a pedal-operate low-displacement master cylir der connected by small bore pi/ ing and short hoses to two cha: sis-mounted Hydro-Air rela valves mounted near the braI4 actuators.

As mentioned earlier, it's nc so much a case of new safei ideas rather its the first tirn they have all been incorporate into one vehicle combinatior One omission from the SAV prr ject is the kerb weight, as no on from the various partie involved seems to have any ide just how much weight has bee added by the various safet extras.

Tags

People: Cedric Ashley
Locations: York

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