Press release
As buses have changed and developed over the years, the demands placed on the articulated joints joining vehicle sections have undergone many changes. The evolution of these components through the decades is presented here by Dr. Stefanie Böge, responsible at HÜBNER GmbH for strategic organizational development in the division for street vehicle gangway systems.
Tight curves,
narrow streets – into the 1950s, buses with attached passenger trailers were
used to overcome the characteristic space problems found in urban settings.
When these trailers were forbidden, various manufacturers designed single or
dual axle vehicle segments that were attached to the main propulsion vehicle by
an articulated connection in order to cope with the limited street space in
cities.
At first it was common to have the second of the three axles be the drive axle in articulated buses. With this arrangement, the bus motor (at this time an underfloor motor) was located in the front of the bus. This design had a number of disadvantages, particularly from a maintenance standpoint. And over time, other disadvantages also became apparent. For example, vehicle manufacturers wanted to have a uniform design for the powertrain. In addition, there were more and more low-floor buses that did not allow for such a construction. As a result, buses with a so-called pusher design have become increasingly popular since the 1980s. In buses of this type, a rear-mounted motor drives the back axle of the articulated bus. With this new design, it was necessary to develop articulation systems that were capable of transferring the altered driving forces from the rear to the front of the vehicle.
HÜBNER GmbH began
producing single components for public transportation more than 50 years ago in
the 1950s. These included folding bellows, for example, which protected the
gangway between the segments of articulated vehicles. As articulated buses
evolved, it was soon recognized that complete articulation systems were
required. It should be possible to use these systems in the widest possible
range of vehicle types and particularly in low-floor buses. In line with these
requirements, a low-floor articulation system for use together with the
existing folding bellows was designed. The issue of a damping system that could
meet the demands of a pusher bus in all kinds of operating situations was also
addressed at this time. The aim was to provide vehicle manufacturers with a
complete solution made up of an articulated connection, a damping system and a
folding bellow that could be used in diverse operating situations and settings.
In the
construction of such complete systems, solutions using modular graphite casting
were preferred from the beginning. The material characteristics of this
approach in the context of the limited construction space in low-floor vehicles
provided a way to realize a system that was both safe and economical. During
the development phase at HÜBNER, measurements and tests were conducted around
the world to determine the requirements arising under different operating
conditions and in different settings so that these could be integrated into the
final design.
However, in the
course of this development phase, it became evident that the initial idea of
developing a universal articulation system for all different vehicle types was
not, in fact, practical. Consequently, as time went on, a range of different
articulation systems were developed to meet different requirements. The aspect
of service-friendly design also came to take on increasing importance.
The universal articulation
system
comes closest to realizing HÜBNER’s original development aim, and it can
be viewed as the “mother” of all HÜBNER articulation systems. It is the most
frequently used system worldwide. Its advantages lie in the simple and clearly
defined connection surfaces allowing for problem-free fitting to the front and
rear vehicle segments. Today it is available in a standard and a deluxe
version, both of which are nearly maintenance free. The main components of the
system such as the bearing, the system control and the damping elements are all
easily accessible. In the event of damage, single dampers can be replaced
individually. Usually the universal articulation system is delivered with an
electronic control system that detects the driving situation, controls the
driving performance and also conducts a system diagnosis for early detection of
any defects.
The heavy-duty
articulation system
has similar characteristics to the universal system, but
has been specially developed for vehicles with higher axle loads (gas or
trolley buses). This connection is used with particular frequency in
New in the
product range is the
compact articulation system
produced by Hemscheidt. Like the universal articulation
system, this product can also be used in all types of articulated buses and
displays a compact design, a simple fitting procedure and a low sensitivity to
dirt and soiling. The integrated damping system is maintenance free and robust.
The system is designed so that all its moving parts are located in an oil bath
and as a result function with virtually no wear. This is the basis of the
system’s low-maintenance requirements.
The ball articulation is somewhat different from other articulation systems. It is simply constructed, economical and resilient, and was specially developed for puller vehicles. Since it also can be used in low-floor vehicles, it additionally can serve as an alternative for pusher vehicles. It is used particularly in articulated buses in
Against the
background of a world transportation market with increasingly divergent
requirements, the family of HÜBNER articulation systems meets all conceivable
demands. This is why most new transportation concepts such as bus rapid transit
systems feature HÜBNER products.
As conditions
continue to change, however, new and continuing product developments are
necessary. For
As a comprehensive system supplier, the HÜBNER Group manufactures key components for the transportation industry (for rail vehicles, buses, airport technology, automobiles and trucks) as well as medical technology products. The range of products and services includes the design and production of folding bellows, vehicle articulation systems, flexible gangway systems, door and window systems, PUR molded foam components as well as products made of rubber and injection molded plastic.
Worldwide more than 20,000 HÜBNER articulated joints are in use today in vehicle produced by such manufacturers as MAN, Mercedes, Neoplan, Solaris, Volve, Irisbus-Iveco and Carrosserie Hess.
Regular maintenance monitoring of the articulation system once a year does not require much time, and can help to avoid expensive secondary damage and vehicle downtimes:
Text: Dr. Stefanie Böge
Pictures: HÜBNER GmbH
