New construction trucks in every segment
The Geneva truck show coincides with Scania's launch of additional 4-series models. Scania's new C-class covers an extremely wide range of heavy construction trucks catering for every application within the segment. The newly-launched models will be gradually phased into series production during the year.
"Construction truck customers place immensely high demands on profitability," says Lennart Sandqvist, head of development for Scania's new construction trucks. "The competition is razor-sharp and everything hinges on squeezing as many loads as possible out of each working day. That is why performance is also a vital competitive factor - because a single missed load per day may represent the loss of one-tenth of the day's income."
Today's customers value the following characteristics in a construction truck:
Reliability. Unplanned downtime can devastate an operation's economy. Ten lost loads owing to a single day's standstill will take a long time to make up.
Payload. This may be the opposite of reliability if the customer chooses a truck specification which is too light, resulting in reliability problems. The solution is a combination of light weight and high strength.
Off-road ability. It is important that the truck can push its way through without requiring costly and time-consuming towing assistance. The powertrain is subjected to considerable stress whenever a truck gets bogged down.
Comfort. A satisfied driver handles and treats his truck better and also does a better job, which in turn improves his competitive edge.
Performance. It is important that there is a reserve of additional power when the going gets really tough. Good manoeuvrability ensures that this power is utilised in the best possible way. Keeping up with the rhythm of regular traffic is also an important consideration.
Running costs. Fuel consumption is not critical in this context since the distances driven are relatively short. Neither is planned maintenance of paramount importance, for the same reason.
Typical construction trucks
Construction truck design varies from one market to another depending on legal requirements and/or local operating traditions. The most common configurations are 4x2 and 6x2 tractors or tippers. The next most common are 8x4 tippers and concrete mixers. Roughly 25% of the 6x4 and 8x4 trucks are concrete mixers.
The construction industry in Germany prefers all-wheel drive vehicles which are also used for on-road operations. Italy specifies trucks in the heaviest category, Great Britain goes for the lightest category, and somewhere in between are Spain, France and Germany.
In the Nordic countries, tag-axle trucks (6x2) are very common in construction operations. This configuration is not offered in Scania's construction truck series but the need will be met by other trucks in the Scania range.
Driving conditionsConstruction operations are characterised by relatively short distances (often less than 60,000 km a year) under extremely demanding conditions. The roads are poor or non-existent. Good off-road ability and a high ground clearance are vital pre-requisites, as are generous angles of approach and departure at the front, rear and below the vehicle.
Gross vehicle weight varies from the standard 26 tonnes up to 150 tonnes at the top end of the scale. The frame can be subjected to immense torsional stress when the underlying surface is uneven or while the load is being tipped. Torsional stress in the powertrain is extremely high in heavy construction operations and is multiplied several times on soft surfaces or when the vehicle gets stuck.
The vehicle's tare weight is particularly important since regular operation also takes the vehicle onto public roads. On heavy construction vehicles, the driving and load-bearing components must always be dimensioned to withstand overloading, and they must be well-matched to ensure maximum reliability under shifting conditions.
The bodywork is often specialised and complex. Several different power take-off systems are needed to power hydraulic systems, pumps etc. Scania's new construction truck range is designed to take all the usual body types and it can easily be modified to accept alternative bodywork. A comprehensive bodywork manual for the new trucks describes the bodybuilding process in detail. The chassis features several attachment points for simpler assembly.
The new C-classScania's new C-class covers models for construction duties in all known applications. The range covers two and three-axle tractors and two, three and four-axle trucks. Two and three-axle trucks are also available with all-wheel drive.
(Detailed information about specifications and combination possibilities can be found in press release P96132.)
In order to tackle poor roads and off-road terrain, Scania's C-class trucks feature stronger frames with higher ground clearance and larger approach and departure angles front and rear than long-haul trucks. The C-class has leaf springs front and rear.
The frames are made of higher strength steel than previously, and they are thus even stronger in relation to their weight. Construction trucks have two frame thicknesses depending on chassis type and strength requirements:
F950 tensile limit 400 N/mm2, 9.5 mm thickness
F950 tensile limit 550 N/mm2, 9.5 mm thickness
F958 tensile limit 400 N/mm2, 9.5 mm thickness, 8 mm inner frame
The frame is V-shaped at the front, so that the radiator, engine and transmission can be tucked lower in the chassis. No components protrude above the frame behind the cab, so the load area can be maximised. Both the wheel and cab suspension systems have been designed for stable progress, consistent driving characteristics, responsive feedback and top comfort. All C-class trucks have leaf springs, in most cases parabolic springs which weigh less than trapezoidal springs, as well as shock absorbers for added comfort.
A high chassis (chassis height H) with a high ground clearance is featured on most models. Owing to special market requirements, for instance in Great Britain, there is a selection of lightweight 6x4 and 8x4 models with normal-height chassis (N). Scania offers a lightweight tandem bogie on these models, to maximise highway payload capacity. Wheelbases vary from 3,100 to 3,700 mm for tractors, stretching up to 6,300 mm for trucks.
Axles and bogies
Lightweight 6x4 and 8x4 trucks with normal (N) chassis height can be ordered with a 6,700 kg front axle load configuration. Other construction trucks - including the all-wheel drive variants - can be specified for 7,100, 7,500, 8,500 and 9,000 kg front axle loads. Twin front axles double the front axle load capacity.
The rear axles on 4x2 trucks are dimensioned for 13,000 or 15,000 kg axle loads. Tandem bogies are available with 19,000 (lightweight 6x4 and 8x4), 21,000, 26,000 or 30,000 kg bogie loads. Bogies from 21 tonnes upwards feature hub reduction (even on driven front axles) to aid off-road capability.
The rear axles on 4x2 trucks are available with or without hub reduction, while 4x4 trucks have hub reduction both front and rear.
Lightweight 6x4 and 8x4 trucks feature a new lighter tandem bogie, driven axles with single reduction gears and parabolic springs. There is also the option of more long-legged ratios for comfortable highway operation. Heavier 6x4 and 8x4 trucks as well as 6x6 trucks feature tandem bogies with a choice of two hub reduction categories. Hub reduction offers higher ground clearance and better off-road capability since there is less risk of powertrain "snatch" on loose surfaces. All tandem bogies are of the balance-type, offering considerable axle movement.
New driven front axle
The driven front axle is a new Scania design. It is equipped with hub reduction, which offers a high ground clearance and maximum off-road capability, at the same time as it withstands front axle loads of up to 9,000 kg. (See also press release P96123.)