Seddon's new 300s till that gap
Page 46
Page 47
If you've noticed an error in this article please click here to report it so we can fix it.
WilF) five new vehicles coming be-ween the 16-ton 200-Series and the 400 range, as Graham Montgomerie reports
SEDDON ATKINSON has announced five new vehicles in the 300-Series to join the sixwheeler which was introduced in late 1978. The new models — three tractive units, an eightwheeler and a 4x2 drawbar rigid — fill the gap between the 16 ton 200-Series and the premium models of the 400 range.
All the new 300 variants, with the exception of the eightwheeler, will be available immediately. The 8x4 chassis will not be going into production until September.
The three tractive units have gross weights of 24, 28 and 32 tons, and like the new rigids share much common components with existing Seddon Atkinson models. For example, the 300 uses the 400 base cab structure, but mounted lower and with the wing panels replaced by those from the 200 cab.
One of the prime design objectives for the new Seddon Atkinsons has been low kerb weight. The 32-ton tractive unit, for example, weighs 5.7 tonnes (5 tons 12cwt) complete with fifth-wheel and a full tank.
As with the existing 300Series six-wheeler, the new ad ditions use the turbocharged International Harvester engine of 7.64 litres (466cuin) capacity. This develops 193kW (194bhp) at 2600rpm as fitted to the 24and 28-ton tractive units.
The remaining three models, however, use the same basic engine, but also have an air-towater charge cooling circuit which pushes the power output up to 160kVV (214bhp) at 250Orpm.
The charge-cooled engine is designated DTi-466; the con ventional turbocharged version is DT-466. The torque figure for the DTi is 705Nm (520 lbft) at 1800rpm, in contrast to the 610Nm (450 lbft) of the DT466.
The clutch used in all the new 300-Series models is the Dana Spicer self-adjusting twin-plate unit with a diameter of 356mm (14in).
As far as the gearbox specification is concerned, the 300 eight-wheeler uses the RT609 from Fuller (with the option of an Allison automatic), while the rest are fitted with various types of ZF gearboxes.
The 24-ton tractive unit is fitted with the same AK6-65 six-speed constant-mesh gearbox already familiar to owners of 300 6x4 chassis. For the remaining models, synchromesh boxes are specified complete with splitter giving 12 forward speeds.
The 28-ton tractive unit is powered by the DT-466 and fitted with the 56-65 gearbox, while the S6-80 is fitted to those chassis with the higher powered DTi version. The GV80 splitter is common to both these gearDoxes.
In contrast to the 400-Series Seddon Atkinson, the gear .:hange follows a -conventiolalchange pattern, that is, it is iota mirror image layout.
As with the choice of engine, Seddon Atkinson has gone inlouse for the axles. The SA 3.5-ton front axle is common to ill while, at the rear, all but the tight-wheeler use the I H RA-57 ixle.
This axle was developed and wilt in the USA where it has ieen in production for the past en years, being standard fitlent on six International hassis. It is a single reduction esign and in the 300 range is available with ratios of 6.14 in the drawbar, 28and 32-ton tractive units; 4.78 in the 24ton version; and 5.57 in the eight-wheeler.
The 300 eight-wheeler — like its six-wheeled predecessor — is fitted with the Eaton 380 bogie, with the I H RA 472 being offered on option.
The chassis frames for all five new models are of ladder construction with bolted crossmembers. With the three tractive units, the section is the same width and thickness as the 400-Series versions, but is shallower in depth and tubular cross-members are fitted.
The actual section for the tractive units is 232 X 89 x 7.9mm (91/8 x 31/2 X 5/16in) while for the 4x2 drawbar it is 276 x 76 X 7.9mm (107/8 X 3 X 5/16in).
in direct contrast to Leyland's shackle ended springs for the Roadtrain, Seddon Atkinson has slipper-ended springs in the rear suspensions which, the company claims, will lessen the risk of spring breakage and keep downtime to a minimum.
As I mentioned, the cab is part of the nationalised 200/ 300/400 cab system with the 300 front grille assembly, for example, being identical to the 400. This provides access to the radiator and dipstick. The cab tilts to 50°, with the actual tilting mechanism being located on the nearside to keep the driver away from traffic.
A sleeper-cab option will become available later in the year, but this will apply only to the tractive units.
The exhaust system, steering components and radiator are all protected within the frame. The wiring is similarly protected and runs under the top of the chassis with insulated earth return wiring being fitted as standard.
The braking system again uses many common components, with the brake width front and rear being 178mm (7in).
The wheelbase for the tractive units is 3.0m (9ft 10in) and 5.64m (18ft 6in) for the drawbar which gives a platform length of 7.3m (24ft). The 8x4 due for next September will have a wheelbase of 5.87m (19ft 3in) to the mid-bogie position.
Prices for the new models are competitive. The tractive units range from £.18,800 for the 24-tonner up to £21,630 for the 32-ton-gcw chassis. The price for the rigid is £22,630 while, not surprisingly, the price of the eight-wheeler will not be announced until September.