Daf time travelling with FCV
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by Danny Coughlan
• In 1989, Europe's truck industry rode upon a rising tide of sales and profit. Economic growth was strong, as was customer demand for ever more innovative commercial vehicles.
Legislation was also particularly active then. The first round of emissions regulations, Euro-1, was approaching fast. Individual countries were imposing their own requirements for new equipment such as road speed limiters, spray suppression and smoke filtration. The Continent went through a number of changes in weight and dimensions legislation, too.
All this activity created a plethora of individual research programmes within the various truck manufacturers. Co-ordinating these was a problem in itself, but focusing them and assessing their relevance in a changing world became the priority Concept trucks, so often seen in Japan, became the tool that would pull together and focus all this research.
Little seen in Europe before, concept trucks soon began appearing at motor shows across the Continent Renault of France, MAN and Mercedes-Benz from Germany and Spain's Pegaso were among those which unveiled futuristic prototypes packed with new technology.
The start It was in the summer of 1989 that the then Daf NV began work on its travelling laboratory. Having inherited the knowledge of the former Leyland Trucks' revolutionary Tx450 programme, Dafs engineers were keen to go a stage further. In particular the team, led by the head of product planning, Hans Staals, wanted to centre their work on a real model. They chose 95 Series and called their truck Future Concept Vehicle (FCV).
Given the many ideas and developments Daf possessed at that time, FCV could have been one of a number of models. Eventually a 5.24-metre wheelbase 6x4 container carrier emerged as the subject vehicle. This was to be no ordinary double-drive rigid, however.
Staals' team began with the chassis. They knew that today's steel designs did the job, but were heavy and often too strong in many places. Having examined many materials, including various resin fibres, the team opted for a box-section backbone in aluminium alloy. Daf says this design is simple and relatively inexpensive. And it could create weight savings of up to 10% in future trucks.
To this construction was welded all the attachments for engine, driveline and cabin, the driveline running inside the box section. Conventional fuel and air tanks were used, but future FCV's could store these fluids in cavities within the chassis.
Concept
The concept of using one component to do two or more jobs is used on Series 95. Here the tubular cab step support doubles as an oil reservoir for the tilt mechanism.
On top of the chassis were mounted ISO standard twistlocks for securing the payload. The flat top can also form part of the floor of a conventional body.
FCV features many items currently seen only on lighter vehicles. These include all-round air suspension independently mounted on axles two and three, disc brakes and active damping control. The last development, from Sachs-Boge, adjusts the damping action of the shock absorbers relative to the road surface.
Other features are unique. These include the eight-stud wheel fixing which overlaps when twin wheels are used, Servotronic speed-dependent variable power steering and gas discharge headlamps.
The last two developments were made in conjunction with ZF and Hell& A total of 11 major component suppliers co-operated on the project including Bosch, Knorr and Wabco.
Daf wanted a twin-steer configuration for good manoeuvrability and low tyre scrub. Good traction demanded a 6x4 configuration, creating a conflict. The answer lay in designing a unique splittorque differential which could apportion drive 33% to the singletyre second axle and 66% to the third axle and its twin tyres. The so-called Double Drive Differential System is known as DDDS.
Both drive axles feature single reduction. With today's European legislation, a DDDS-equipped bogie can power a truck/trailer combination of up to 48 tonnes gross train weight
Low profile
The 19.5in alloy wheels are fitted with Michelin low profile 315/70 R19.5 XZA tyres. This reduces deck height to just 850mm while retaining 220mm ground clearance. Guiding the second steering axle was best achieved using existing electro/hydraulic technology, it was found, though the link between steering column; the control box remains mechanical.
The disc brake system employs Knorr two air-over-hydraulic calipers on each wheel. Full air
disc brakes were not available in 1989, but they are today and will be fitted to future FCVs, Hans Staals told us.
Where to position the discs was a problem. The small wheels were too small and so the discs had to move inwards.
On the front axle they are positioned outside the chassis. At the rear there was room to mount them inside. This was necessary to make room for the heavier fourair-bag suspension system on axle three. Moving them so far inboard can help reduce maintenance time. Brake cooling has also improved by a factor of six, Daf
ABS-equipped Fcv is, of course, equipped with full ABS braking, but more importantly it has ASR traction control to prevent wheel slip.
Daf's long-serving 11.6-litre, six-cylinder engine range was engineered into the chassis. The conventional 16-speed ZF synchromesh gearbox is controlled from the cab by the company's electronic Easyshift system.
To ensure close fitment of the body behind the cab the rear bulkhead has been kept as clean as possible. The engine is mounted well forward under the cab, its top half protruding up through a rectangular hole cut in the top of the chassis. The 'engine is partly encapsulated reducing noise. Its position at the front of the frame demanded that the cooling and charge-cooler radiators be moved, one to either side.
To the left lies the water radiator, folded into a vee-shape to fit inside the confined space below the flat cabin floor (the same technique is used on many Formula 1 racing cars). To the right is the charge-cooler. Daf says that arranging the two radiators in this way reduces power consumption from 11kW to 6.5kW It also enables the two hydraulically driven fans to work less and, by linking them electronically, permits better control of the engine.
The charge-cooler radiator sits just ahead of a cluster of components which centralise all the auxiliary power taken from the engine. Here lies the alternator, air compressor, steering pump plus a conventional hydraulic power take-off arranged in a single assembly. The aim is to provide a single, interchangeable unit which can be removed quickly in the event of a failure.
Design
Daf 's engineers have put much into the design of the front end, says Staals. The work has • included designing-in front crumple zone characteristics using technology borrowed from the motor-car industry. Future FCVs will explore this criteria even more, particularly in the light of proposed legislation.
The cabin started life as a standard day cab model with top sleeper. It has been equipped with electric tilt mechanism as well as experimental driver and passenger seats supplied by Isringhausen. The display for a reversing camera is mounted on the dashboard just to the driver's right.
The usual cab steps could not be used because of the position of the radiators behind the bumper bar.
Instead twin air-operated steps descend automatically whenever the door on that side is opened. When closed the steps retract leaving a smooth aerodynamic surface.
The FCV project has been reborn within the new company Daf Trucks. This company was created on 2 March 1993 following the collapse into receivership of Daf NV Freed of debt, Daf Trucks aims to go on developing its own heavy trucks in readiness for the environmental, legal and safety demands of the next century. Clearly FCV has many more miles to go.