|Total Number of Engines Built||20|
|First Engine Built||1901|
|Last Engine Built||1902|
|First Engine Written Off||1942|
|Last Engine Written Off||1951|
These were the first genuine suburban tank locomotive on QR and were restricted to the Brisbane suburban area. All engines were initially attached to Mayne but later some were transferred to Wooloongabba.
The class suffered from initial teething problems and a number of modifications were carried out during their life. They were originally built as 4-6-2T but later altered to 4-6-4T wheel arrangement. The original boilers with Belpaire fireboxes were replaced with standard style boiler with round top firebox between 1912 and 1918. Other alterations included replacing the original regulator with a standard pull out type, increasing the bunker capacity and fitting sand boxes on top of the boiler.
Experiments with burning coke were carried out during 1912 in an endeavour to reduce smoke nuisance on suburban trains.
Together with 6D13½ Abt engines for Mount Morgan Rack Section, they were the first engines with 12TAL.
In an attempt to extend their range, two were converted to B16D engines by adding a B15 type tender but retaining their side tanks. The conversion was considered only moderately successful. These two engines were then principally used on suburban goods trains.
By the mid 1930s, increasing numbers of the new D17 class gradually took over the bulk of suburban work from their aging saturated predecessors.
That twelve of the engines were written off in 1942-43, a period of severe motive power shortage, is indicative of their poor condition at that time.
Deliveries of the new DD17 class saw the last of the engines withdrawn. N°372 was the last of the class to be written off in December 1951.
Walkers – Walkers Ltd, Engineers, Maryborough