ZF Low-Floor Technology Paves The Way To Efficient Transport Concepts

Low-floor buses have become firmly established in European public transport systems and ZF is the company that pioneered the special axle technology for full-length, low-floor city buses. Passengers not only benefit from convenient entry and exit, waiting times at bus stops are also much shorter.

Low-floor technology has opened the door to a versatile, bus-based concept known as Bus Rapid Transit (BRT). The most outstanding example of this system is in Beijing, site of the 2008 Summer Olympics.

Europeans have long since become accustomed to boarding city buses and inter-city travel coaches comfortably, without steps. They have also come to expect a flat center aisle without raised platforms. In low-floor buses, everything is on the same level. ZF pioneered this technology with special portal drive axles that make it possible to build full-length, low-floor vehicles.

Low-profile portal drive axles

ZF Passau GmbH, the ZF Off-Road Driveline Technology and Axle Systems Division, started supplying the first driven portal axles back in 1983. Today, ZF Passau is the technology leader in this for with a 90-percent market share. Just a few weeks ago, the company produced portal axle number 100,000 in the current AV 132 product generation. This specially designed axle reduces door well height to a mere 405 mm at the rear axle. ZF engineers gained the space required for the flat center aisle by lowering the weight-optimized axle bridge and designing a side-mounted differential to transfer drive power. Along with these design advantages, AV 132 portal axles are well-known on the market for extremely quiet operation, which is achieved with specially-processed bevel gears.

Product highlight: low-profile independent front suspension systems (IFS)

Along with the advanced low-floor technology for drive axles, ZF supplies the AVN 132 non-driven portal axle for installation as a low-floor center axle in longer, articulated buses. ZF also offers a variety of solutions for front axles, including the classic RL 85 A front axle with rigid axle bridges that are extremely robust, easy to maintain, and are available as active or passive trailing axles for 3-axle city buses.

A new product highlight is the RL 75 EC low-profile independent front suspension system. IFS allows for greater steering angles that give longer bi-articulated buses the required maneuverability. IFS also improves vehicle roll/steering characteristics, as well as riding comfort and safety.

Growing demand from abroad

Not only passengers benefit from the advantages of ZF low-floor technology. Low-floor buses significantly reduce entry and exit times. With this in mind, major cities in South America and Asia are increasingly relying on a versatile concept that works particularly well with low-floor buses: Bus Rapid Transit (BRT). This system is currently being used in Beijing, the site of the 2008 Summer Olympic Games. BRT combines the system advantages of rail travel with the flexibility of buses. In Beijing these buses serve the main traffic arteries of the city with dedicated bus lanes. An intelligent control system for traffic lights gives the vehicles right of way so BRT buses are never kept waiting at red lights. Passengers who want to use the rapid bus line purchase their tickets before boarding and quickly enter the vehicle without having to climb steps – thanks to low-profile portal axles from ZF.

Investment costs for low-floor technology are significantly lower than for rail systems, and urban planners appreciate the flexibility. Thus, the growing popularity of the BRT system is expected to drive continued demand for ZF portal axles. So it won't be long before the company celebrates its next production milestone.

Source: ZF

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