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  Construction site vehicles 4




How to move around on a construction site? The best way to do it, is to drive. Indeed, this is not as simple as it sounds. Apart from that, through the systems described in the previous pages, the tare of the vehicles has been considerably increased.

For the engineer familiar with the regulations concerning the permissible road-strain, this automatically means, one additional axle. This may be in the front or in the rear and has, first of all, nothing to do with the number of driven axles.

However, curves in the road are the death of vehicles having a lot of wheels, they eat away at the tyres and guzzle fuel. For this reason, the truck-axles must be steerable, either with a leading- (picture 3 below) and/or a trailing axle (pictures 1 & 2 below), or the axle must be to lift when little or no cargo is on board (picture 2). It's an advantage, that during regular cornering, the steering of the non-driven axles is possible, it would be more expensive, if the driven axles also had to be steerable.


Unfortunately, all that the description 8x4/4 tells us is that all in all, there are four axles and that two of them are either driven or are steerable. Normally one would assume two steerable axles up front and two non- steerable but driven axles at the rear. Indeed, they can also be distributed differently.

Much more important, e.g., than in long-distance haulage, is that construction site vehicles must have more ground clearance. In all-wheel drive vehicles this may be endangered by the presence of a large transfer case (picture 7). Indeed, also the final drive in the rigid axle may pose a problem. One falls back on the planetary hub reduction (pictures 5 and 6).

The video below shows quite well, how the steering can be done by hydraulics. Indeed, the question being asked here, is how can a vehicle like this be towed when the engine is not running? Either the steering axle is raised from the ground, or the still rotating cardan shaft produces the necessary hydraulic power. 11/14


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