Fine stretch of dual carriageway surrounded on all sides by

16th September 1966, Page 13

16th September 1966

Page 13

Page 15

Page 13, 16th September 1966 — Fine stretch of dual carriageway surrounded on all sides by

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gently rolling countryside. Extensive road works between Gretna and Kirtlebridge—steering the 38 ft-long Sixteen: Four through a series of complicated diversions is a tricky task.

George talks about the merits of having the trailer close to the cab as opposed to some feet away, which it is on the Sixteen:Four. 'It's very seldom you do get a really smooth ride with an articulated vehicle, but the trailer seems to be too far back and it tends to bring the front end up into the air and you get that bouncing effect. Having the trailer twelve or eighteen inches nearer the cab would help reduce that.'

Seddon Design Team: With the Sixteen:Four we decided it was time to go for a longer wheelbase-9 ft 3 in— which is safer and more stable than a short wheelbase tractor on braking and all-round handling. What happened in the past, with the old overall length regulation of 35 feet, everyone was trying to produce a short wheelbase tractor to get the maximum length trailer behind it. Then when the revised 'Construction and Use' Regulations came along, increasing that overall length to 42 ft 7 in, it gave us an opportunity to design a long wheelbase tractor, and the advantages of this far outweigh the disadvantages. The short kingpin position on the trailer emphasises the gap between the back of the cab and the head-boaril—the fifth wheel is in fact several inches further forward than on the short wheelbase tractor.

But to return to thefront-end lifting problem. This is probably due more to the veryflexible front springs, which add greatly to driver comfort. The vehicle is lifting off the springs rather than off the road, and as George Hamlett points out, very seldom do you get a completely smooth ride with an artic.

1135 am: A74 north of Lockerhie. Cruising at 47 mph down the dual carriageway and a sudden burst of sunshine brings out the best in this beautiful countryside. Distinct impression that the road gets smoother and wider every mile further north. On the right the Glasgow express rattles the rails as it thunders on to Mauchester. More road improvements hereabout, piles of earth everywhere, lorries loading and unloading, and scores of brownbacked workmen sweating under the climbing *n. Heat in the cab is increasing—caused more by the sun than the pounding engine. In fact the engine itself is behaving perfectly, maintaining an even temperature following two or three hours continuous running, and the cowling inside the cab is barely warm, evidence that the insulating material is well up to the job.

Seddon Design Team: The cowling is lined internally with polystyrene, backed with a hardened skin facing the engine to minimise deterioration, and this lining will be thickened and further improved on the final version of the Sixteen: Four. We've carried out extensive tests using red hot plates to simulate engine heat, one inch away from the polystyrene, and the heat just couldn't get through, absolutely none at all.

We're concerned with two things here, noise and heat in the cab, with the emphasis on reducing the noise level. This particular material has brought the noise level down by as much as fifteen decibels—by far the best figure of all materials we've tried. I personally can endorse what the driver has said because I took this vehicle out on test minus the polystyrene insulation and noticed a marked increase in noise and heat.

George is thumping the engine on the approach to Beattock. Atop a steep hillside a hotel built like a castle stares down on forty shades of pine trees. Below the pine forest a stream cut deep into the rock looks as though it abounds in freshwater salmon. George feels stiff after his long stint at the wheel. Eases himself back in the seat and squints ahead along the glittering tarmac: rising heat waves distort the size and speed of approaching vehicles. An oncoming BRS rig flashes its lights in recognition. George grins and flicks a switch. 'Word gets around. Even north of the Border they know I'm driving the new Sixteen:Four.'

Surprising how the engine can keep 22 tons rolling at such a pace for so long. 'Seems to me a good time for this run,' George remarks. 'Started early, of course, kept it going and didn't have the traffic until the halfway stage. That early start makes a big difference because you get a lot of heavy stuff—the low loaders—on the road after seven o'clock. This run gets very narrow in places and they hold you up unless you're away first.' In his view there's been a tremenc improvement in vehicle design over re years: bigger engines, better transmis systems, gearbox and so forth, but he thinks driver comfort—ergonomic doesn't receive the attention it deserves manufacturers. The cab of the Sixteen:F on the other hand, is a really first-rate e by the Seddon Design Team: exce vision, easy-to-read dials, switches controls near at hand, etc. One thing he , criticise, however, is the position of the stick. 'It's a nice box but difficult to properly because the stick is smack ir centre of the cowling. If it was bro closer and more direct you could usc gearbox ti) its best advantage.'

Seddon Design Team: This is one criticism we didn't ex) considering the exhaustive test prograi carried out on the Sixteen:Four, but rz, theless George Hamlett is looking at from the haulage driver's point-of-view so we've carried out a thorough investigc to see what can be done. Of course quite impossible to re-site the gearbox —that would amount to a major strum alteration—but what we have done I offset the gear linkage, thus bringinl gearstick six inches nearer the driver. enables him to get a better, more po! change and indeed our test drivers that it's a definite improvement.

George Hamlett's remarks regarding fort and accessibility of controls echo own feelings as to what constitutes a cab. The flexibly-mounted cab of Sixteen :Four has been designed from sc, to make life a lot easier for the eh 12.16 pm: Beattocke approaching Crawford. Superb scenery and one of the finest dual carriageways in the country: gradients the Sixteen:Four takes in its stride— matching the speed of a van half its size-then opening up to 55-60 mph on the level. Turning off the A74 for a midday meal at the Merindale Cafe.

George :Hamlett is now familiar enough with the Sixteen:Four to record his impressions thus far. Over meat pie and chips and a steaming mug of tea: 'This is without doubt a good all-round vehicle. Strong engine, runs very even, pulls well and if you keep the revs up on the hills it's surprising what the engine will do. There seems to be more power in the V8 than sounds to be coming out, something always in reserve. To be honest, it quite definitely surprised me.

'I had a touch of backache earlier but that was just the newness. I don't think you can blame the cab or the seating. You've got to break yourself down to a new vehicle; the vehicle won't bed itself down to you, naturally.

'I like the idea of the treble braking system and the modulating valve. This knocks a certain amount of pressure off the driving wheels when the vehicle is empty and transfers it to the other wheels. This is automatic. I should imagine this will cut out jack-knifing or certainly help to minimise it.' Seddon Design Team: The Sixteen:Four has two independent braking systems. This is to comply with the proposed amendments to the 'Construction and Use' Regulations regarding plated vehicles. We've developed a complete braking system which includes a foot-operated service brake, a hand-operated auxiliary brake—known as the 'dead man'—and a multi-pull handbrake for parking purposes.

The tractor unit uses a dual service foot valve. One valve section feeds the front and rear axle service brakes on the tractor while the other section supplies air to the trailer's relay valve via the flexible service line. With this method of piping you achieve automatic tractor protection. In the event of failure of the trailer coupling hoses or a trailer break-away, the tractor service brake is unaffected.

Now about the light/laden valve George Hamlett mentions. When you remove the payload from a vehicle the drive axle is the one most likely to lock—because it's subject to the greatest variation in weight— and that's how jack-knifing occurs. This is where the modulating valve on the Sixteen: Four comes into action. It reduces the operating pressure on the drive axle by approximately 75 per cent, so you get maximum pressure when the vehicle is laden and this is reduced by 75 per cent when the unit is running light. The system is fully automatic, working from the deflection of the springs on the trailer. There's c second time lag which solves the pro. of going over a bump which might frac ally lift the load.

We should perhaps emphasise light/laden valve isn't standard; we're fi it as called for.

1.20 pm: back on the A74. Last leg of with 30-odd miles to go. Magnificent : with wide, banked bends sweeping dow Abington. Eager to arrive, George pu the Sixteen:Four past 50 mph and engine responds as crisply as ever. river on the right, renowned for its sal and trout, runs down to the Clyde. Sh; Highland cattle grazing beside dark gr of pines. All signs now point to Glas Through the village of Blackwoe Colville's tall steel towers visible dow the valley at Motherwell.

2.10 pm: Hamilton town centre. S traffic build-up in this typically Sec high street where the shops and house: constructed from hewn granite blc Along London Road twenty minutes passing the City boundary into Gla. itself. Up ahead the Celtic floodlights s silhouetted against a ridge of b cumulus cloud.

Richton Cross where the old men gregate, past the Royal Infirmary `1., like the nick', says George—and ai Cathedral Square, known to the loca Town Head.