• Museum of Fire Heritage Team

The Dennis "Big 4"

The Dennis “Big 4” was named according to its engine size, designed with a 4-cylinder overhead valve engine with a RAC horsepower rating of 35.7. Between the years of 1934 and 1939 the New South Wales Fire Brigade (NSWFB) used Dennis Bros almost exclusively. It was in 1937 that the Brigade ordered its first Big 4 which was to be delivered as an unbodied chassis.

Dennis Big 4 No. 268 at Colo Vale, c. 1970.

Charged with the design of the body, the Brigade’s draughtsmen proposed several designs. They were inspired by the new style “limousine” bodywork supplied to the London Brigade and attempted to design a closed-cabin body that would provide seating for up to eight people (including the driver and officer) in a three row arrangement.

In this version, the rear mounted fire pump was to be completely exposed which resulted in a short body with very little room for hoses and equipment. The standard “Braidwood” design however was decided as most suitable, and subsequently was constructed. In this design, the unit could carry up to eight firefighters with the crew sitting on top of the hose box.

NSWFB drawing of a “Braidwood” style body for the “Big 4”.

Front cover of ‘Fire’, April 1936, featuring the “Big 4”.

The first Big 4 entered service at Redfern Fire Station in November 1937 with a second unit commissioned at Headquarters in October 1938. A further eight units arrived in late 1939 entering service between 1940 and 1942 at a number of inner-city stations. To take full advantage of the 650+ centrifugal pump, four gated deliveries were fitted for firefighting efforts. Nine of the ten units were later converted into “foam pumpers”, fitted with Wormald foam systems. The foam storage tank was located behind the driver’s seat (and was often mistaken for the fuel tank which was located under the driver’s seat!).

When plans to replace the Big 4 were arranged, the fire pumps were removed from the units for re-use. Due to their foam-making ability, the ‘pump-less’ Big 4s remained as spares until as late as 1972.

Dennis Big 4 No. 268 at Mittagong Railway Station, photography for 1974 AWA Calendar

The Museum’s Big 4

Of the ten vehicles built by the NSWFB, the Museum’s collection includes one Big 4 appliance which has been fully restored to operational condition. The Museum’s Big 4 was delivered as a chassis from Dennis Bros in the UK in December 1939. Once it arrived in Sydney, it was fitted with bodywork in the NSWFB workshops, and entered service at Balmain Fire Station in December 1940 with fleet number 268 Motor Engine (ME). After almost six years of service, it was fitted with the Wormald Foam System in October of 1946.

In 1956 the appliance was transferred to Marrickville and then to Mascot in 1960. In 1967 the main pump was removed for re-use, but it remained in service as a stand-alone foam unit until it was withdrawn from service in 1968. A private collector later restored the unit to full operating condition, and then donated it to the Museum in 1986. During 1999 to 2000, the Big 4 underwent further restoration and continues to be fully functional, regularly being taken out on parade.

Pictured here is the Museum's Big 4.

-Museum of Fire Collection Management Team

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