There were one hundred and twenty one QN vehicles built for ballasting and maintenance work between 1901 and 1920's. QN's were numbered 1 - 121.
The vehicles featured bottom discharge for ballast work and a flat floor with steel plates across the hoppers for strengthening and for support when carrying rails.
Rail carrying in these vehicle probably stopped with the introduction of _KR_ rail carrying trucks in the late 1950's, which was about the start of long rail transportation.
The vehicles ran on plateframe bogies with some vehicles being fitted with cast bogies in the 1960's/1970's: 1 and 116 to mention two wagons.
Most vehicles ran within districts and were stencilled for the loading location. Ruby in South Gippsland was one such location, Marong near Bendigo another.
QN 31 was fitted with a cement mixer and associated equipment. It appears the vehicle was used for the installation of electrical overhead masts along the suburban routes. A photo shows the wagon in the late 1930's after conversion to autocouplers. It was photographed in the 1970's converted back for standard use.
QN's were all built to the same 'pattern'. However the QN vehicles built in the mid 1920's have a slightly different side arrangement. From correspondence, the underframes left over from the _NN_ to _O__ hopper wagon project were to be used for the construction of _QR_ wagons. Inspection of photographs showed no underframes with splices but the QN's built about the same time show splices in the side frames. These are QN's numbered 92 - 121 and they feature a splice plate towards one end of the vehicle.
What has yet to be determined is whether the frame joins are diagonal for each side or whether the joins are at the same end for both sides. The railway General Arrangements do not show the splice.