7,000 wheels for Rotterdam

The 1,070 metre Maastunnel runs under the Nieuwe Maas. Over 75,000 motor vehicles and 7,000 bicycles and mopeds use the tunnel every day. The tunnel also provides eight escalators for the hundreds of pedestrians who go through the tunnel each day. Each escalator is 45 metres long and goes as far as 21 metres below ground level at an incline of 30 degrees. The escalators were assessed as part of an extensive overhaul of the tunnel’s facilities. The experts in Rotterdam found that their wheels had worn down over the years. After looking for a replacement, the city administration found what they were looking for in Rosenfeld.

The transport experts were looking for “the best wheels for the escalators in the Maastunnel national monument.” 3,500 running wheels and chain wheels were needed for the escalators to work properly. A tailored solution was the only answer due to the large wheel diameters involved and the fact that the wheels needed to vary in thickness. The biggest challenge: the wheels had to fit on the existing axle of the step chain. To ensure a long service life, the city’s specifications only permitted a very small amount of play in the wheel. Rosenfeld-based wheel and castor specialists Blickle were contacted as part of the city’s search for a suitable partner.

After analysing the requirements in detail, Blickle’s experts designed a prototype and put it through a demanding series of tests. The wheels needed to be both impact resistant and chemically resistant to water, oil, salt, grease and degreaser. They also needed to have enough friction resistance to avoid slipping on the metal track while withstanding temperatures from minus five to 40 degrees Celsius. The specifications even called for the wheels to be self-extinguishing in the event of a fire and to use thermoplastic materials which meet the user’s fire safety requirements. The outcome of these tests and the cost/benefit analysis ultimately convinced the decision-makers in Rotterdam to award the contract to Blickle in Rosenfeld.

Blickle developed running wheels with a diameter of 180 x 30 mm and chain wheels with a diameter of 180 x 40 mm. These provided the Rotterdam administration with a wide range of advantages. The heavy duty wheels use a flame-retardant and a glass fibre reinforced nylon 6 tread with a hardness of 80 Shore D. Precision-turned wheel centres provide outstanding concentricity. Resilient grooved and angular contact ball bearings are included to ensure a service life in excess of 25 years. The inner and outer rings of the grooved ball bearings are symmetrical, making the running wheels quiet and smooth. The rings of the angular contact ball bearings used for the chain wheels are asymmetric for outstanding radial and axial load capacity. The wheels extinguish themselves within 30 seconds, smoulder for up to 60 seconds and don’t produce any burning material. The bearings use special covers to prevent soiling.

• Resilient, glass fibre reinforced nylon 6 tread.
• Special covers for the bearing units keep maintenance to a minimum.
• Special ball bearings for outstanding radial and axial load capacity.
• Long-term solution for the customer.