STRATOCRUISER TOUCHES DOWN
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Seddon Atkinson goes up market with its new Strato premium tractive unit. Under the Cabtec cab is a range of new engines, drivelines and chassis.
• Seddon Atkinson has made the move expected since it was acquired by Pegaso by launching a new premium tractive unit using the joint Enasa/Daf Cabtec cab. The new vehicle — named Strato — not only replaces the 14-year-old 400-series, but takes Seddon Atkinson further up market into true premium vehicles.
The Strato is in essence a completely new vehicle, with little carried over from its predecessor. There is a new frame, new engines, gearboxes and axles.
The frame is similar to that of the 4-11, but has been narrowed at the rear to accommodate the 12R22.5 tyres of the 400 variant.
The springs (taper leaf at the front, multi-leaf at the rear) are longer than before, for improved ride, but there is not, as yet, an air suspension option.
The engines at this stage are all Cummins units — two 10-litre models and three 14-litres. The 10-litres are both air-to-air charge-cooled variants, with power outputs (to ISO gross ratings) of 224kW (300hp) and 242kW (325hp).
Seddon Atkinson is the first customer for the "300" engine, which is a downrated version of the "325". It has been chosen instead of the more obvious noncharge-cooled LTA10-290 for commonality of installation.
POWER RATINGS
The big four-litre engines are available in three power ratings: 239, 261 and 298kW (320, 350 and 400hp). All the engines have exhaust brakes and viscous-drive fans, and all have heated fuel filters. Each is connected to an air-assisted twin-plate ceramic clutch: 356mm diameter on the 10-litre models and 394mm diameter on the 14-litres.
In a major change from the old models, Eaton's Twin Splitter 12-speed gearbox is the standard fitting, with no other options yet listed.
All but the Strato 400 have the TS 11612 model, the highest-power Strato getting the heavier TS 13612 box. Following Foden's lead, Seddon Atkinson has fitted an American-made Cablecraft cable linkage to this gearbox: the lever is attached to the cab floor, thus eliminating sealing and cab-movement problems.
Drive in all cases is taken to the latest generation of Rockwell single-reduction hypoid axle. The most powerful Strato has the S180E which was fitted to the last of the 4-11s; all other models will be fitted with the S160E axle.
The front axle in all cases is Seddon Atkinson's own unit, unchanged from its previous installations and fitted, like the rear axles, with Rockwell S Cam brakes (which are now supplied by three air reservoirs instead of four, fitted with a single-pull drain valve).
The Strato is so far available only as a 4x 2 tractive unit, and only with Cummins engines.
The range will be augmented by a 6x2 twin-steer tractor next year, and a revised version of the Perkins Eagle engine will also appear as an option. Until the 6x2 Strato appears, the 4-11 6x2 will stay in production, as will the 3-11 tractors. Apart from the lightweight 3-11 tractor, all others will cease production in mid-1989, the lightweight continuing in production until 1990.
There are three basic cabs, a short day cab, a twin-berth sleeper cab and a highroofed version named "Stratocruiser". All are structurally identical to their Pegaso Troner equivalents and are built and trimmed entirely by Enasa in Spain, being shipped to Oldham six at a time in special trailers.
The luxurious Stratocruiser cab is some 30cm taller than the other two, and the day cab is 43cm shorter than those with sleeper accommodation.
Although the new models are not strictly comparable with the old, Seddon Atkinson says there are useful weight savings, of around 200kg, and that the Strato is lighter than the Leyland Daf 95 on equivalent models.
With the Strato comes a muchenhanced support package. The vehicle has a five-year warranty against corrosion, subject to an annual inspection and rectification at the company's expense. There is a 12-month unlimited-distance full parts and labour warranty, with a no-cost "5 star" second-year warranty covering some parts and labour costs, calculated on a declining scale.
Beyond that, there is an optional Truckshield top-up warranty covering the second, third and fourth years.
Prices for day-cab models range from 236,700 to 239,600; for sleeper-cab mod els from £38,000 to £42,750; and for Stratocruisers from £39,350 to £44,000. The lightest day-cab 10-litre model weighs 5,800kg, and even the Stratocruiser cab only increases that to 6,020kg. The big Strato 400 is not available in day-cabbed form, but weighs 6,330kg in sleeper form, and 6,400kg in Stratocruiser form.
IMPRESSIONS
Seddon Atkinson Strato represents a quantum leap in style and sophistication — a leap at least as big as that by which the orginal 400 surpassed the old Borderer. It is, in comparison with its predecessor, an altogether smoother and more upmarket vehicle, much more competitive with other manufacturers 240-300kW machines.
As might be expected, the Strato cab is almost identical to that of the Pegaso Troner, and therefore to that of the Leyland Oaf 95. The uniquely Seddon Atkinson bits are the front grille and badging. The main difference between the Strato/ Troner and the 95 is in the floorpan, which has to accomodate extra permutations of engines and left/right-hand drive in the former case,
There is noticeable (but well-damped) cab roll, while the tall Stratocruiser cab retains the excellent electronically controlled air suspension seen on the Troner and 95 high-cab variants. The cab is well, but not outstandingly, equipped, having elec
tric windows and an lsringhausen suspension seat as standard, and electric heating (but not adjustment) for the big external mirrors.
The most noticeable difference between the Strato and the 95 is the distinctive rattle of the 14-litre Cw-nmions engine. Those who love the noise will be delighted; those who don't will find the Strato cab a slightly noisier workplace than many of its competitors.
That said, the Strato cab is wellinsulated, with little wind noise, and is quieter than anything which Seddon Atkinson has offered before. The Stratocruiser cab, in particular, is a most civilised place in which to work.
Another major difference lies in the Cablecraft gear linkage for the Eaton Twin Splitter gearbox. This is an area where Seddon Atkinson and Eaton still have some work to do to match the shift qualities of some competitors.
The throws across the gate are very long, but the biggest problem on these admittedly very new vehicles was in getting the gearlever to move without using the clutch on a downchange on the overrun, as when cruising up to a set of traffic lights. The lighter (and better-run-in) box fitted to the 350 Strato was better in this respect.
RATIO SPREADS
Gearchange quibbles apart, the characteristics of the big Cummins engines seem well-matched to the Eaton box with its unusual ratio spreads. Round the short suburban test route, the 400 in particular spent most of the time with the gearlever in "4", relying on the splits alone. At 64km/h in top on the standard 3.21:1 drive axle, the big Cummins is just in its green band, at 1,100rpm, and is quite happy to pull from there.
The Rockwell brakes are a little fierce in light applications (further bedding-in would undoubtedly help) but reassuringly powerful when used in anger. They are backed up by a good, strong Cummins engine brake (no Jacobs engine brakes yet on the Strato) with its front control button mounted admirably on the left footrest.
LI by Allan Winn