The first true mainline locomotives of the Victorian Railways were 34 2-4-0 passenger locomotives introduced in 1862. Today better known as class B, they only got this designation in 1886. Originally wood-fired, they had two chambers in the firebox which could be fired individually. These locomotives had outside frames, inside cylinders and outside coupling rods, leading to the nickname “Overarmers”.

In 1861 and 1862, 17 each were built in Britain by Black, Hawthorn & Co. and Beyer, Peacock & Co. In 1872, six more were built by the second of these two manufacturers. As late as in 1880, two more were completed in Australia by Phoenix Foundry of Ballarat. Originally, they carried numbers between 32 and 87 with gaps. When passenger locomotives only got even numbers, they received new numbers between 46 and 188.

In the 1880s, they were outclassed by new 4-4-0 locomotives. Additionally, newer branch lines were constructed in a cheaper way than the original ones, so that the 2-4-0 locomotives with their rigid chassis were not very suited for these lines. Nevertheless, their boiler pressure was increased from 130 to 140 psi and the cylinders were enlarged from 16 to 17 or even 17 and a half inches. Their withdrawals came between 1904 and 1917. In 1952, the first mainline diesel locomotive of the VR again became class B.