NEW 'PREMIUM` SCAMMELL 32-TONNER FOR BRSL
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4 x 2 Crusader for State transport fleet
by Gibb Grace,
DAuE, CEng, MIMechE AT the request of British Road Services Ltd, ' and with the company's engineering co-operation, Scammell Lorries Ltd has designed a new 32-ton-gcw tractive unit based on the Crusader first produced in six-wheeled form in 1968. As yet this promising new hybrid has no model designation but it is readily distinguishable from the parent Crusader in being a 4x2.
Few customers have the power to affect manufacturers' thinking to the extent of BRSL but it is interesting to note Scammell's flexibility in being able to produce a "premium" truck of this nature. Interesting, too, to note BRSL's involvement in promoting a new British product in this special category when less nationalistic customers might simply have ordered something foreign.
This particular model is exclusive to BRSL for the present but a two-axle Crusader will become more generally available from the end of this year; it will follow the same general layout but its detail specification will be rather different.
The Crusader has to my mind, whether through accident or design, always been an impressive-looking vehicle; styling plays an active part in everybody's life today and the rugged, almost aggressive looks of this tractive unit will appeal to most drivers. The ubiquitous Coventry Motor Panels cab is opened up to full width, given a split screen and finished off with an angular glass-fibre radiator moulding. This surrounds an externally mounted Kysor shutter, thermostatically controlled.
Very American proportions are a result of raising the cab floor to clear the engine and stretching the wheelbase to lift 3in. (favoured by BRSL to give correct weight distribution, especially if new weights come in). The high-level engine air intake behind the cab, the Western mirrors and the airflow deflectors on the door hinge post—intended to keep windows and mirrors free from road dirt—complete the picture. The rectangular headlamps are made by Cibie.
Chassis
BRSL's requirement for a new tractive unit was centred on three main components which had shown up well in the company's own statistical checks on service reliability—the Rolls-Royce Eagle engine, the Leyland hub-reduction axle and the Fuller twin-countershaft gearbox. (The
Thornycroft box had shown up equally well, but the Fuller was chosen because TET was just in the process of redesigning its unit.)
Scammell was willing and able to produce a tractive unit built around these three components and incorporating other features--such as excellent engine accessibility and a sprung cab for driver comfort—which BRSL rated highly. The heavy-duty specification of the 6x4 Crusader also corresponded with BRSL's interest in having a premium truck in which reliability and longevity consciously outweighed considerations of first cost —particularly in view of long-term plans for intensive freight trunking. But BRSL had no immediate call for a three-axle tractive unit, so Scammell set out to design a 4x2 version of the Crusader.
Not surprisingly, there are similarities between the two models. The chassis frame, for instance, retains the widened front end designed to accept the General Motors V8 normally used with the heavy Crusader. This has the important result that accessibility to the smaller Rolls engine is excellent, and the space around the engine also contributes to reducing noise transmitted to the cab.
Cross-members are bolted to the side-members which have the same modulus as previously but are unflitched. SPrings are mounted outboard of the side-members at the rear and under them at the front: in spite of this the swept turning circle is big at 46ft gin. left and 50ft 9in. right. Integral power steering is fitted as standard. Soft springs and a good ride were features of the original Crusader which was designed to run on the rough roads of the world's export markets, and the front springs and dampers are retained; the rear springs are new and similarly long and have a low rate: dampers are not fitted, however.
Both front and rear springs have a rubber-bushed leading mounting and a slipper rear mounting. This arrangement has proved on the original Crusader to need little or no maintenance and to have a long life. The spring gets stiffer as it is loaded because its length is effectively shortened, a desirable feature of any suspension. Full air brakes using a three-line system are fitted as previously. Spring brake units are fitted to all wheels. Brake shoes have 7in.-wide linings front and rear and are expanded by cam action.
Special consideration has been given to the coupling arrangements. The very substantial fifth-wheel is designed to promote artie stability and it offers three positions—which can be increased to six by taking the mount off and turning it. The fifth-wheel is mounted about l--in. higher than normal on BRSL artics. but the light Engine, transmission and driveline A Rolls-Royce Eagle 220 engine producing 220 bhp at 2100 rpm is fitted as standard and is mated to a Fuller twin-countershaft gearbox Type RT909. This has nine forward speeds and two reverse and a torque input rating of up to 900 lb ft—sufficient to cope with the 265 bhp turbocharged engine which will be fitted to four of the initial 22 production vehicles.
A leaf transverse spring is fitted between the gearbox and the main frame, to permit relative movement and at the same time provide damping. An American LipeRollway clutch is used.
The rear axle, plated at 10.2 tons, is a Leyland hub-reduction unit; the front axle is plated for 6.5 tons.
Although the steel cab is high by normal British standards the floor is not flat right across; an engine cover stands proud by some 7 or 8in, but this is nonetheless a considerable improvement. The standard of instrumentation is very good indeed; all instruments are mounted on a matt black surface and very easy to read. The all-important speedometer and rev counter are mounted side by side immediately behind the wheel. To the left-hand side of the wheel is the parking brake lever. Pedal layout is excellent and seat adjustment adequate. The co-driver's seat is quite luxurious: it reclines and has an integral headrest. Both seats are covered in a woven wool /nylon cloth which "breathes" and prevents one "sticking" to the seat—a feature which I hope will become universal. To further improve the ride the whole cab is mounted on coil springs with integral telescopic dampers. Batteries and the air intake are located outside the cab.