English - Nooteboom Giants on the Road Magazine English - Nr. 6 - 2019 | Page 54

GIANTS ON THE ROAD The suspension movement is absorbed by the resistance that the oil flow encounters during the back and forth pumping action between the cylinder and the accumulator. The hydraulic system is completely closed so an uncoupled trailer will stay at the same height – even after weeks. HYDRAULIC PRESSURE AND LIFESPAN ■   nsteered 4-axle low-loader with detachable 4th axle on U RB suspension (1986) Nooteboom has already delivered 10,000 vehicles with hydraulic suspension. These many years of experience are reflected in the specifications. For good road holding it is essential that every wheel reacts quickly to an uneven road surface. In that case a system with high pressure and a small quantity of pumped oil is desirable. But lower pressure and cylinders with a bigger diameter are better for a longer lifespan. In order to guarantee good road holding as well as a long lifespan Nooteboom employs a system with medium pressures (80-160 bar). The cylinders are manufactured using the ‘Nooteboom’ specifications, with the emphasis on low maintenance costs. The stainless steel, hard chrome-plated piston rod is optimally protected against corrosion and wear and the seals are adjustable. STABILITY ■   -axle trailer semi low-loader on RB suspension with detachable rear 4 section with hydraulic ramps (1990) The accumulators have another feature that is characteristic for trailers with hydraulic suspension: they work progressively. This means that the pressure increases quickly if the trailer begins to roll. The driver has an extremely stable trailer and not just during cornering. When travelling straight ahead on a motorway a steered trailer with hydraulic suspension is much ‘calmer’ than a trailer with air suspension. Why is there such a big difference between hydraulic suspension and air suspension? On a trailer with air suspension the rebound of the bellows on the inside bend side of the trailer is considerable since there is no progressivity. With hydraulic suspension this is different: on the inside bend side after a certain degree of rebound the pressure is quickly reduced so that the trailer will roll less to the right. In a word: anyone who often transports a load with a high centre of gravity should not consider anything but hydraulic suspension. The efficient axle load compensation is also a big advantage during braking. Each wheel has the same wheel pressure and the same brake pressure, which prevents the lock up of one wheel. VERSIONS ■  ■  54 S  teered 4-axle low-loader on HR suspension and 1-axle Jeepdolly on RB suspension (1985)  nsteered low-loader with RB suspension, the rearmost 2 axles are U detachable. The 1-axle Jeepdolly is removable (1984) Nooteboom developed the first axle with hydraulic suspension - the HR version - in 1976. The R in this case stands for ‘round axle’. It won’t come as a surprise that after the round axle a hydraulic suspension was developed for a square axle too. The name should have been HV but it was still called the HR. But in 1980 a cheaper version was developed, which was going to be the HR/B1. This version was shortened to RB. Within the Nooteboom organisation there is a persistent rumour that these were the initials of the designer. The suspension stroke was 200 mm and the suspension was designed for 13-tonne axles and 8.25R15 tyres (similar to the current 245/70 R 17.5 tyres). The RB was further developed as the RB/3, for low semi low-loaders with 205/65R17.5 tyres. On the HR version the hydraulic cylinder is placed in front of the axle and on a RB version behind the axle. Because the suspension has a lever action around the shackle pin, the suspension stroke on the HR version (up to 300 mm) is much longer than on the RB version (approx. 200 mm). The first drawbar trailer with pendle axles and hydraulic suspension was delivered in 1975 to Getron from Spijkenisse. The 96-tonne