The Kenworth T900 is typical of the "big rigs" that cruise across the Australian Outback with 2 or 3 trailers in tow. The T900 is similar to its US equivalent the W900 but has special features that allow it to operate better in the harsh desert environment. These include special air filters, huge fuel tanks for extended range, heavy duty air-conditioning, and "bull bars" which protect the truck from collisions with wild animals. Trucks of this type are powered by Caterpiller, Cummins or Detroit diesel engines of 350 - 500 hp.