Traversing Off Roads - The International 6x6 Mk-5

The 1968 International 6x6 Tanker from the Maroota South Bush Fire Brigade, Baulkham Hills, 1999 [Museum of Fire Collection]

In the early 1950s, the Australian Army's fleet of offroad, medium (3 tonne) and heavy (5 tonne) trucks

still comprised mainly of Canadian built 4x4 and U.S. built 6x6 chassis, carried over from the WWII era. Approaches were made to various local truck manufacturers with respect to developing a new range of specialised forward control vehicles with a high local manufacturing content. The International Harvester Company, situated in Melbourne, was the only company with the required resources, and so

began developing prototypes for evaluation. The first trial units were delivered from 1955, with the first 100 production vehicles completed by early 1959 using the company's conventional AS chassis. Eventually, over 1300 of the medium 4x4 units in MK 1, 2, 3 and 4 variants were produced through to

about 1964.

Development of a 6x6 version commenced in 1958, but production did not begin until 1966, when the first of some 390 examples, known as the 'Mark 5', were delivered over a period of seven years. The MK-5 was a 5 tonne capacity chassis powered by an International 150 hp petrol engine of 283 cu.in (4.6 litre) capacity, driving through a 5-speed Fuller gearbox and 2-speed transfer case. A 9 tonne winch was also fitted. It was made in 'General Service Cargo' tipper, or heavy recovery truck configurations. Large single tyres were fitted all around to reduce damage.

International 6x6 attached to the NSW Bush Fire Brigades in Hornsby Shire. [Museum of Fire Collection]

1973 OLD BONALBO BUSH FIRE BRIGADE MK-5

The Museum of Fire's Internatinal 6x6 MK-5 was originally acquired by the Old Bonalbo Bush Fire Brigade near Casino, Kyogle Shire, in 1984. The appliance was acquired through Government Stores and the Bushfire Fighting Fund.

A local landowner donated the crew cab, which was fitted at the council depot. Brigade members also installed the water tank, pump and plumbing, and repainted the bodywork. The appliance was judged 'Best Heavy Tanker' at a Northern Region Bush Fire Brigades Activity Day at Grafton, NSW, in 1991. It remained in front-line service there until retired in 2003.

Many of these types of International appliances and trucks were acquired by Rural Bush

Fire Brigades at the end of their service with the Australian Army, often replacing aging

military equivalent vehicles.

International 6x6 attached to Old Bonalbo Bush Fire Brigade at the Museum of Fire [Museum of Fire Collection]

~Blog by Museum of Fire Heritage Team