The DD17 class steam locomotive

Steam locomotive

A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

 was a 4-6-4T locomotive of the Queensland Railways (QR).

The locomotives operated on 1,067 mm (3 ft 6 in) gauge. The significance of the first "D" is in line with the QR loco classing system where the letter referred to the number of coupled wheels. "A" refers to 4 coupled driving wheels, "B" to 6, "C" to 8 and "D" to 6 on a tank locomotive

Tank locomotive

A tank locomotive or tank engine is a steam locomotive that carries its water in one or more on-board water tanks, instead of pulling it behind it in a tender. It will most likely also have some kind of bunker to hold the fuel. There are several different types of tank locomotive dependent upon...

. The second "D" indicates an improved version of the earlier D17 class and the number "17" indicates the cylinder diameter of 17 inches. The DD17 class was built to provide more powerful motive power to the Brisbane suburban network.

Numbering

All 12 locomotives were built at Ipswich workshops and given works numbers 199-210. Running numbers were 949-954 and 1046-1051.

Preservation

Four are still in existence:

• No. 1046 is stored dismantled on the Zig Zag Railway
  Zig Zag Railway
  The Zig Zag Railway is a heritage railway at Lithgow in New South Wales, Australia on the site of the famous Great or Lithgow Zig Zag which operated between 1869 and 1910. As built, the line formed part of the Main West line from Sydney across the Blue Mountains and served to lower the line from...
  
  , Lithgow, NSW having been used in preservation between 1975 and the mid 1980's.
• No. 1047 is stored on the Zig Zag Railway
  Zig Zag Railway
  The Zig Zag Railway is a heritage railway at Lithgow in New South Wales, Australia on the site of the famous Great or Lithgow Zig Zag which operated between 1869 and 1910. As built, the line formed part of the Main West line from Sydney across the Blue Mountains and served to lower the line from...
  
  , Lithgow, NSW having been used in preservation between the 1970's and the mid 1990's.
• No. 1049 is operational on the Zig Zag Railway
  Zig Zag Railway
  The Zig Zag Railway is a heritage railway at Lithgow in New South Wales, Australia on the site of the famous Great or Lithgow Zig Zag which operated between 1869 and 1910. As built, the line formed part of the Main West line from Sydney across the Blue Mountains and served to lower the line from...
  
  , Lithgow, NSW. It was restored to operation in the 1990's.
• No. 1051 is operational at the Workshops Rail Museum, in Ipswich, Queensland.