Dunbar Steam Engine's
Lubricator - No. 1 Engine
and
Lubricator - No. 2 Engine
Site Feed Lubricator for No. 1 Steam Engine
by
Bruce Wm. Anderson
There were two lubricators used on the Dunbar steam engines. The No. 1 steam engine used a oil displacement lubricator while the No. 2 steam engine used a metered flow lubricator. The lubricant is often called steam cylinder oil and has a very thick viscosity (thickness). This thickness and the oils tendency to scatter out over the steam engine's inner surfaces rather than to form droplets maintains the oils lubricating qualities at the high temperature of steam (212° plus). This oil lubricates the slide valve, piston, piston rings, piston rod, and rod packing of the steam engine. This steam cylinder oil is difficult to obtain. A substitution for steam cylinder oil may be MOBIL ONE Synthetic Oil of 400 viscosity according to internet steam enthusiasts. We have not tried this yet.
Picture A
Oil Displacement Lubricator
Oil Displacement Lubricator
Picture B
Oil Displacement Lubricator Valve Disassembled
Oil Displacement Lubricator Valve Disassembled
Picture C
Oil Displacement Lubricator Oil Reservoir Disassembled
Oil Displacement Lubricator Oil Reservoir Disassembled
The oil displacement lubricator consists of (Pictures A-E): 1) the valve body, 2) the condensing tower, 3) the oil reservoir, 4) the oil metering valve with packing nut, 5) the water draining valve, 6) the hard maple knob, round headed screw, and brass filling plug for the reservoir, 7) the oil site glass consists of the brass mounting ring, a mica window glass (real glass was used in later years) and two gaskets, 8) the two 1/8 inch tubes internal to the oil reservoir [the water delivery tube (long tube with curved down lip)] and [the oil overflow tube (short curved up tube) (Picture B & D)].
Picture F
Left - Dunbar Oil Displacement Lubricator
Right - An Early Dunbar Oil Displacement Lubricator - We have only seen one of these and the left needle valve controls the water inlet from the condensing tower. We assume they decided this water inlet valve was unnecessary?
Left - Dunbar Oil Displacement Lubricator
Right - An Early Dunbar Oil Displacement Lubricator - We have only seen one of these and the left needle valve controls the water inlet from the condensing tower. We assume they decided this water inlet valve was unnecessary?
THEORY OF OPERATION OF THE OIL DISPLACEMENT LUBRICATOR: The lubricator is attached to the steam supply line just before the steam chest. Some amount of steam enters the condensing tower and condenses into water. One half of this water (the water on the side of the condensing tower towards the oil reservoir) will drain by gravity into the oil reservoir through the long 1/8 inch tube with the curved down lip.
(We have only seen one early oil displacement lubricator where the inlet water (condensed steam) must travel through an adjustable needle valve into the oil reservoir (Picture F). ) For each drop of water flowing into the oil reservoir – one drop of oil will flow out through the short curved up 1/8 inch tube. This oil is further regulated by the metering needle valve on the side of the lubricator. This oil is then streamed into the steam flow by a short 1/8 inch brass pipe extension with the end usually cut at an angle. Over time, the reservoir oil is displaced by water. When the water shows up in the mica (glass) site glass the water draining valve on the bottom of the oil reservoir should be opened and the water will drain out leaving the unused steam cylinder oil. The unused steam cylinder oil will not flow out the small hole in the water drain valve due to its increased viscosity (thickness). Removing the hard maple knob and the attached filler plug allows steam cylinder oil to be added into the top of the oil reservoir. Oil should be added to the reservoir to a level of one half of the mica (glass) site glass and then the filler plug should be replaced.
Lubricator for No. 2 Steam Engine
by
Bruce Wm. Anderson
The lubricator is used to provide lubrication to the slide valve, piston, piston rings, piston rod, and rod packing of the steam engine. The No. 2 steam engine used a metered flow lubricator (Pictures G, H, & I). The lubricant is often called steam cylinder oil and has a very thick viscosity (thickness) to maintain its lubricating qualities at the high temperature of steam (212° plus).
The metered flow lubricator consists of: 1) the one piece valve body and oil reservoir, 2) the metering needle valve and packing nut, 3) the oil reservoir square metal plug which is removed to fill the reservoir.
THEORY OF OPERATION OF THE METERED FLOW LUBRICATOR: steam cylinder oil should be added to the top of the oil reservoir by removing the square metal plug. The oil metering valve should be cracked open to provide a slow stream of steam cylinder oil to the steam engine. You will need to frequently fill this reservoir as there is no way to monitor the level of the oil.
The metered flow lubricator consists of: 1) the one piece valve body and oil reservoir, 2) the metering needle valve and packing nut, 3) the oil reservoir square metal plug which is removed to fill the reservoir.
THEORY OF OPERATION OF THE METERED FLOW LUBRICATOR: steam cylinder oil should be added to the top of the oil reservoir by removing the square metal plug. The oil metering valve should be cracked open to provide a slow stream of steam cylinder oil to the steam engine. You will need to frequently fill this reservoir as there is no way to monitor the level of the oil.
Picture G
Metered Flow Lubricator for No. 2 Engine
Metered Flow Lubricator for No. 2 Engine
Picture H
Metered Flow Lubricator on No. 2 Dunbar Steam Engine
Metered Flow Lubricator on No. 2 Dunbar Steam Engine
Picture I
Metered Flow Lubricator on Dunbar No. 2 Steam Engine
Metered Flow Lubricator on Dunbar No. 2 Steam Engine