The highest and fastest lift in the world

by Jörg Hellmich, BÖHNKE + PARTNER GmbH

Superlatives dominate our lives, since to customers they make products more interesting and these can consequently be more easily sold. But what is the »highest« lift in the world? A lift with the greatest lifting height or the highest location? If the location is the criterion, then the company BOHNKE + PARTNER was definitely involved in building one of the highest lifts. But where is the highest lift? In Kuala Lumpur, Shanghai, New York or Moscow?

Around the world in a lift

All of these places are possible, since the lift is in a Boeing 747-300 and travels round the world with it. The lift in an aircraft with a peak altitude of 13,700 m is doubtless among the highest and with its 920 km/h the fastest lifts in the world. But in an aircraft very special rules apply - a great challenge for a control manufacturer.

For instance, the onboard voltage of 115 V / 400 Hz, an unimaginable profusion of unfamiliar regulations, the requirement for lightweight building, the strict requirements for electromagnetic compatibility and resistance to shocks and vibrations were new territory for lift and control building. But all these challenges could be overcome and consequently this lift in a government craft from the Middle East has now been flying round the world for several years.

Wide-bodied aircraft with undreamt of potential

The idea of the new European wide-bo­died aircraft Airbus A380 has thrilled the whole of Europe. The successful maiden flight and many reports on the development, construction and tests of this new flagship have often been published in the media.

In the development of this giant aircraft completely new approaches were implemented: "impossible" was and is not in Airbus' vocabulary. Every wish was examined, the possibility of its realisation offered in solution variations. Thought has naturally also been given to installing a lift in this aircraft. Here too a completely new approach is to be tried. Thus the idea arose that the lift should not only travel between three floors inside the aircraft, but should also descend to the runway. On the one hand this would facilitate the catering and on the other the boarding of passengers in wheelchairs.

Special construction with main- and additional mast

In mechanical terms alone this lift represented a challenge, since here neither an hydraulic nor a conventional cable lift could be used. For this lift a special construction made with main- and additional masts was developed. The cabin can be extended out of the fuselage of the aircraft on the additional mast. The drive of the main and additional mast is carried out by means of four synchronous motors controlled by converters via synchronous belts, two each for the main and additional belt. Since the drive is slip-free thanks to the synchronous belts used, the position identification can be carried out to a millimetre via absolute encoders in the synchronous motors.

CANopen bus system

The position is by these means redundantly established by the four converters and transmitted via the CANopen bus to the controls. The synchronisation of the four engines represented a further challenge. The two motors for the main mast are connected with each other by a fixed shaft. Here the torque of the two motors has to be compared with each other very precisely to avoid destroying the shaft. The two motors of the additional mast cannot be linked mechanically with each other. Since the additional mast could get bent, the synchronism of both motors must likewise be very exact. This is guaranteed here solely by electronic means.

Safety enjoys priority

For the regulation of the journey it had to be guaranteed that the speeds of the main- and additional masts cumulated. It was ensured by means of comprehensive measurement and control engineering technology that the additional mast can only be extended from the body if the aircraft is stationary on the ground. Incorrect operations were precluded technically. Sensors which constantly monitor the area beneath the cabin make sure that during the downwards movement there are no obstacles or people under the cabin. If there is anything in this area, this leads to the immediate stop of the cabin. An emergency signal indicates the danger and warns people of the risk area. The distance to the ground is permanently measured by means of ultra-sound sensors. These measurement results control the deceleration of the speed shortly before the touch down of the cabin on the ground. After touch down the brakes must be released to permit the aircraft movement play during loading and unloading.

Use in scheduled airliners possible

Many more peculiarities had to be taken into account in this project and new solutions worked out for them. It is still not clear when this lift will be used in scheduled airliners. Even if the start of the series production of the Airbus A380 is somewhat delayed, the realisation of this giant aircraft does show the efficiency of European engineers, which also represents an important criterion for Germany as a business location. More information as well as a short film showing the functions of the lift are available at www.boehnkepartner.de/referenzen/.