Plate 18A Aerobridge	18B Aerobridge	18C Caterpillar	18D Caterpillar

(Source: http://www.google.co.in/search?hl=en&q=aerobridge&um=1&ie=UTF8&tbm=isch&source
=og&sa=N&tab=wi&ei=qLY5UJ-dDciJrAez0YHYBA&biw=1328&bih=574&sei=xLY5UNnGLIrqrQeQ7
4Bg ; Aug. 26, 2012)

The air-bridge (plate 18A) joins the body of the aircraft to the airport main structure with the help of bellow that can adjust the height and the angles. The vertical and horizontal level of the aircraft exist/ entrance-door and the entrance/ exist door of the airport may vary. The bellow system (plate 18B) helps to adjust the height and the position (vertical and horizontal level) connecting to the main building. Because the bellow system it has made the parking of the aircraft and the connection between the two rigid members possible. It provides comfort and safety to the passengers.

Interestingly in nature there are insects or other living beings they function exactly in similar fashion with the help of bellow structure. When caterpillars (plate 18C&D) try the travel on tree branches they can move very efficiently because of their inbuilt bellow system. It can take difficult routes on the branches (vertical/ horizontal) with the help of their bellow mechanism and travel comfortably to change the direction.

19A Shoe-sole Bellow Design	19B Stool Design	19C Rubber horn