Does anyone know when the Southern Pacific began the conversion from wood/coal fired locomotives to oil firing? Specifically I want to know if the A3 class Atlantics were delivered from the builder as oil fired or converted at a later date?
According to Diebert and Strapac “SP Steam Locomotive Compendium” SP started converting locomotives from coal to oil in 1900. Baldwin built its first oil burning locomotives for SP in 1901. The last woodburner (in Oregon, where wood was cheap) was converted to oil in 1915.
There is no direct evidence that the A-3s were built as oil burners, but no conversion dates appear for conversion to oil except for four built as coal burners for the SP de Mexico, but converted to oil burners at Sacramento in 1913 after transfer to US lines. The previous class A-2 had Vanderbilt fireboxes, unsuitable for coal burning and old photos of the A-1 class show them to be oil burners.
I would say that it is most likely that all the A-3 class built for the SP proper were all built as oil burners. The Baldwin builder’s photo of 3048, built 1906, shows the oil tank in the tender, but an air tank hides the ash pan (or lack of one). By the way, 3048 had a rectangular tender when new, built to Harriman standards, since the design was used for other roads using coal fuel.
It would be safe to assume that all were built as oil burners.
Peter