Portugalete is a small town of some 50,000 inhabitants, not far from Bilbao, in the Basque region of Spain. The town was founded in 1322 on the estuary of the river Nerviòn. This happy choice of location led to the successful development first of trade then, later in history, of industry too. As the town’s prosperity grew, its infrastructures too had to be developed to serve the needs of economic growth.

In 1893, industrial expansion led to the construction of one of the earliest but most innovative river crossing systems in the world: the BIZKAIA SUSPENSION BRIDGE.

The bridge is constructed from riveted steel girders (with a structural design not dissimilar to that of the Eiffel tower). A bogey runs under the span of the bridge and carries a gondola suspended on 18 steel cables, capable of transporting pedestrians and vehicles from one side of the river to the other. The empty weight of the gondola is 20 tons.

It has been calculated that since the bridge first opened, it has carried some 650 million passengers across the river Nerviòn, in crossings that have continued uninterrupted 365 days a year, 24 hours a day. The gondola departs every eight minutes and takes one and a half minutes to complete the crossing. In 113 years of operation, the Bizkaia suspension bridge’s gondola has travelled a distance equivalent to 31 times the circumference of the world.

In consideration of its amazing performance, practical usefulness and original design, the Bizkaia suspension bridge has been put forward for recognition by Unesco under the World Heritage scheme.

The bridge is now driven by twelve F302 UH40 24.4 P112 H3 gearboxes powered by 2.2 kW, 3,000 rpm electric motors with encoder control. Rated torque is 176 Nm and the duty cycle is 1.9. The gear motors are controlled by closed loop vectorial frequency converters.

The main problems deriving from the application are continuous all year round operation, massive inertia (varying from 20 to 50 tons), and an aggressive marine environment. Another strict requirement is the need to ensure excellent passenger comfort in addition to total reliability.Bonfiglioli parallel shaft helical gearboxes were selected as the most suitable product for the application because of their low noise operation and reduced angular play (which translates into greater comfort) in suspended installations. Their use also ensures that the installation is unaffected by radial loading generated by alignment errors between the bogey frame and its wheels. A high duty factor was calculated to suit input power (S:2.5) and the installation position (H3) was chosen to ensure that all gearbox components run in a permanent oil-bath. The operational reliability that the application demands is thus guaranteed.To ensure that the drive system is adequately protected against the salt air, the gearboxes are fitted with Viton® seals and are externally finished in a 200 μm coating of RAL9010 white epoxy paint.Bonfiglioli is extremely proud of the fact that our products have been chosen to drive the prestigious Bizkaia suspension bridge. Their installation at Bizkaia is further proof that Bonfiglioli has all the technical skills needed to tackle even the most challenging applications, and that this ability is indeed recognised by an expert market. Applications like the Bizkaia suspension bridge inspire us with the confidence to accept even the most ambitious challenges, in the knowledge that we have all the human and technical resources we need to succeed.