English - Nooteboom Giants on the Road Magazine English - Nr. 6 - 2019 - Page 55

HISTORY ADBAN drawbar trailer was pulled by a Scania 140 6x4 tractor. Hydraulic suspension for pendle axles is known at Nooteboom under the abbreviation HP. OPTIONS Raising and lowering the trailer is different than it is on a trailer with air suspension, where one simply releases and pumps up air. There are two options: a built-in pump or the oil can be drained or replenished from outside. To lift the axles there are two options as well. The first one can only be used if the trailer is equipped with a pump. In that case the procedure is as follows: first lower the trailer completely. Then the suspension of one or more axles is shut with a valve. The axle is then locked with a chain, turnbuckle or locking pin. When the trailer is pumped up and put at ride height again the lift axles will remain suspended above the ground. Another – more modern – option is to use double-acting cylinders. By adding oil at the bottom of the cylinder the axle is lifted. This system is known under the name “power-up”. In the engineering department of Nooteboom they have been working for a while on the next generation of trailers with hydraulic suspension. They will not be for sale soon. Why not? At Nooteboom the suspension is first of all overloaded for a long time in a test setup. This is followed by tests in practice by carefully selected customers for at least a year. Going to so much trouble for a part of the trailer that you cannot even see? Yes, because these invisible components are the basis for a next generation of Nooteboom trailers with even better specifications and even lower maintenance costs.  ■ SIGNALLING AXLE PRESSURE AND RIDE HEIGHT Transports travelling across Europe often have to comply with different regulations for axle pressures on parts of their journey. If pressure gauges are fitted the driver can pretty well work out the pressure on the axles. This prevents unnecessary fines and road wear but it is also benefits the lifespan and repair costs of the trailer. Another useful option is the indicator light that operates via sensors. Even in the dark the driver can see when the normal ride height is reached. ■  RB suspension(rigid axle) ■  RB suspension(rigid axle) ■  HR suspension(rigid axle) MAINTENANCE Nooteboom has been delivering trailers with hydraulic suspension since 1975. Since those days the quality of the components has increased dramatically. But heavy transport operators are conservative. Sometimes an old hand in the profession will grumble: ‘A cylinder underneath the trailer is never going to work, what about dirt and stone chippings?’ Whoever believes this has not paid attention in the last few years. The maintenance costs of hydraulic suspension are anno 2018 exceptionally low. Due to the beneficial axle pressure compensation the tyres and brake lining enjoy a long lifespan. Shock absorbers are not fitted, so they don’t need replacing either. And the progressive suspension ensures the mechanical parts, such as the parabolic springs and silent-blocs are not overburdened. HYDRAULIC SUSPENSION, STEERING AND GOOSENECK WITH COMPENSATION Hydraulic steering and suspension are two separate systems that are not connected. This is different for a gooseneck with hydraulic compensation. For trailers up to five axles a fixed neck is sufficient. But for a long trailer with many axles a neck that can increase the compensation while driving is preferable. This is achieved by hydraulically connecting the front axles with the gooseneck. An addition here is a differentiator which, by turning one single lever, makes the hydraulic gooseneck suitable for the maximum permissible fifth wheel pressure of a 6x4 or 8x4 tractor. At the beginning of this story – in 1975 – the detachable gooseneck had just been invented. The steering of the axles was done mechanically with rods and the suspension? Leaf spring suspension was the standard. Older mechanics can still recall how they had to replace a broken leaf spring bolt or a leaf in a spring assembly nearly every week. We quickly forget, but the hydraulic suspension of today is infinitely more reliable and maintenance-friendly. 55