Baldwin Locomotive Works in the United States supplied the first two 2-6-2tank locomotives, as well as parts for a further two locos. One each of the supplied locos and the parts kits was a simple loco, and the other a compound. These Locos were never officially classed other than Narrow Gauge Loco, the A was there to indicate they were the second Loco to use the Number, the NA reference came about though workshop staff becoming Lazy when referring to Narrow Gauge Loco #A. The Victorian Railways Newport workshops assembled the parts to give an additional two locos, and subsequently built a further 13 of the simple cylinder version. The last one, number 17, was built in 1915.
By the mid-1920s these small locomotives were not able to handle the increasing traffic, and two G classGarratt locomotives were purchased to supplement the fleet.
The locomotives weigh 36.58 long tons (37.17 t; 40.97 short tons) and produce a tractive effort of 12,170 lbf (54.1 kN), allowing them to haul loads of 90 long tons (91 t; 100 short tons) up grades of 1 in 30 (3.33%). Numbers 6, 7, 8, 12, and 14 have been restored and operate on the Puffing Billy Railway, and No. 3 is also on the Puffing Billy Railway, awaiting eventual restoration. The remaining locomotives have all been scrapped.