Drip....drip....drip. With his pocket watch and a small flashlight, Sierra #3 Engineer Dave Tadlock adjusts the oil feed rate on his locomotive's Detroit Lubricator. Although steam locomotives have a plethora of external lubricating cups and grease fittings, one of the most important lubricating appliances on the engine is the one that supplies oil to the cylinders and valves. Typically, this is done by continually feeding small amounts of oil to the live steam that is being fed from the boiler to the cylinders. On many locomotives, a hydrostatic lubricator such as this one is located in the cab, allowing the crew to not only monitor the rate of lubrication, but also to top off the reservoir without leaving the cab. The flow of oil may be observed through the tiny windows that you see near the base of the lubricator body. Oil drops emerge from valves at the bottom of each window, and rise in a chamber full of water, only to be drawn up into the steam lines above via suction created by flowing boiler steam. The crew can use the valves at the bottom of the lubricator body to adjust the rate at which the drops are released and that rate is determined with an eagle eye and a watch as Dave is doing here. The little flashlight provides back light, making it easier for him to see the little drops as they rise in the glass.
And ya'll probably thought that all of the oilin' was done with a can....