Vallejo Mill. On a beautiful, sunny day in February, Clover Valley Lumber Co. #4 climbs the grade at Vallejo Mill with a local freight consist in tow, headed for Niles Yard, perhaps a half mile ahead. Vallejo Mill is the historical location of a large flour mill, which existed along this line when it was part of the first transcontinental railroad.
Saddle tank rod engines, such as #4 here, were quite popular with logging operations in the early part of the 20th century. These engines were somewhat more capable on steep grades than conventional tender-equipped engines, because all of the weight of the water supply was squarely over the drivers. And unlike a geared engine, such as a Shay, a locomotive like this would retain decent speed, when used on level track. They could also run in either direction easily, and visibility for the crew was actually better running in reverse. The downsides were that water and fuel supplies were typically somewhat more limited, so a fuel and water infrastructure was necessary if the line were of any length. Another possible downside is that water in a saddle tank does get heated to some degree and the locomotive's injectors might not function as efficiently if the water got too warm. One possible way to mitigate the supply and temperature problems would be to haul an auxiliary water car behind the engine, as was done for this photo charter. The extra water supply eliminated the need to stop frequently, and cool water could occasionally be pumped from the tanker, to keep the water in the saddle tanks cooler.
Scenes of Clover Valley Lumber Company #4 and Columbia River Belt Line Railway #7 in action with freight and log trains, on a portion of the original Transcontinental Railroad.