Bosch Rexroth, represented locally by Hytec, recently collaborated with French company TLD Europe to develop a towbar-less aircraft tractor. This need emerged in response to the development of the A380 Airbus, billed as the largest commercial aircraft in the world.
TLD Europe, a world-wide specialist in technical solutions for ground handling operations, undertook the challenge to develop the TPX 500 S towbar-less aircraft tractor for this new dimension of aircraft, while staying true to their company philosophy: innovative, simple, reliable. The TPX 500 S is a towbar-less aircraft tractor which considerably simplifies the coupling of the plane to the towing vehicle, greatly improving safety and efficiency at the same time.
The vehicle, with a U-shaped tail, drives backwards towards the nose landing gear of the Airbus, and then encloses the front landing gear. Hatches lock onto the front landing gear framework. The push blade then drives forward and fixes the wheels to the hatches. This is where the show of power begins: The towing tractor then lifts the nose landing gear - and as such, the aircraft - to transport it. Even though the Airbus engineers were able to limit the weight of this giant aircraft, designed to carry up to 555 passengers, to 600 t when fully loaded, by using new types of materials, it is still 50% heavier than current long-haul aircraft.
In order to make the towbar-less aircraft tractor powerful enough for the A380, TLD worked in close co-operation with Rexroth on the development and design of the hydraulic power unit. The hydraulic system reliably supplies the required power for the 600 t giant by means of two A4VG axial piston double pumps and two A6VM axial piston variable displacement motors with a power rating of 583 kW. The traction drive control design is based on the hydro-mechanic DA traction drive control system which is sensitive but robust and easy to assemble.
"The advantages of Rexroth components lay in the fact that the products were already available in series production. This means we are guaranteed established and reliable equipment with international and uncomplicated customer service," explains Hervé Criquillion, CEO of TLD Europe.
The fully automated latching and release of the towbar-less technology significantly increases safety and efficiency. Only one operator is required for the TPX 500 S and has a direct line of vision to the aircraft landing gear. The time-consuming handling process, which was prone to accidents and used heavy towbars and coupling devices, is now completely redundant. With the 'shouldering' technique, TLD has simplified and sped up the whole process considerably.
Additionally, the locking mechanism of the TPX 500 S, which is without play, protects the nose landing gear and can take over all transport tasks. The towing tractor then pushes the Airbus backwards into the take-off position (the so-called pushback) or pulls the aircraft to areas of the airport that are further away. This innovative solution guarantees considerably smoother acceleration and breaking manoeuvres, which protects the landing gear as well as the passengers.
TLD and Rexroth set their sights on as simple a solution as possible by reducing the number of lifting cylinders. In this way the TPX 500 S fulfils the constantly increasing demands of end users with regard to improved reliability and longer service life. The volume of air traffic is growing rapidly the world over and the airport service industry is also in the grip of this change.
"Our equipment is now used for 3500 hours instead of 1500 hours per year," notes Criquillion. "At the same time, the product life expectancy has doubled from 10 to 20 years."
During development, TLD made use of Rexroth's branch competence in mobile applications. "We are not hydraulics specialists," says Criquillion. "In that respect we rely on our partner company who can offer world-wide technical know-how and service to our 250 customers in 100 countries."
In collaboration with the Rexroth specialists, TLD mastered the development in under 12 months from project start to delivery. TLD builds around 150 towing tractors per year, all of which are equipped with Rexroth components and systems. In the future, the TPX 500 aircraft tractor will also be supplied for other versions of the A380, for example for the 'Ultimate Freighter', planned for 2008.
For more information contact Willem Gijzelaar, Hytec Holdings, 011 979 4630.
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