Victor Shattock Mechanical Lubricator
Here's an oil pump to insure the lubrication of locomotive cylinders.
by Victor T. Shattock
(President, Golden Gate Live Steamers)
Followers of the hobby of building live steam locomotives are well aware of the importance of lubrication being furnished to the cylinders and valves of their small locomotives, particularly so when superheated steam is used in connection with bronze of similar cylinders; hence, the mechanical lubricator.
The most popular type of mechanical lubricator is made by placing a small oscillating cylinder inside a container and operating it from some moving part of the engine through a ratchet drive thereby pumping oil into the steam chests or pipe lines to the cylinder chests as the builder may select.
Sometime between 1934 and 1936, I read an article by L.B.S.C. in the Model Engineer which described a lubricator made by a gentleman by the name of Cole. The valve oil was contained in a tank of reservoir, this being located under the running board and containing a control valve with which the oil could be regulated to drip into a sump from where it was pumped into the cylinders. The pump had one valve only; the later being at the rear of the pump body with a cork washer, spring loaded, to retain the oil after the plunger had forced it in.
A few years later I had occasion to place a mechanical lubricator on one of my 2-1/2" gauge engines, and I used this idea with the exception that I substituted a spring loaded ball in place of the cork washer. I have now used this principle of mechanical lubrication on three of my engines and have just placed two of these lubricators, one on each side, of my latest 3/4" scale Pacific. Several of my friends have also used this type of lubricator on their engines, one of which is an "O" gauge. The body of the pump on this "O" gauge engine is about the size of an ordinary pencil. With the thought that others may wish to make use of this type of lubricator, I pass the idea along for their use. The sketch illustrates the completed process.
The body of the pump is a block of brass 1" x 1/2" x 1-1/2" long. A hole is drilled through the block, as appearing on the sketch, with a No. 31 drill and reamed 1/8" to take the plunger. This hole can be threaded in one end 8-32 for the plug. The plug should be left off until the pump is ready for assembling as it may be necessary to run the reamer through the bore again.
The block can now be drilled for the ball valve. Drill down from top with a No. 45 drill, penetrating the bore. Follow down with a No. 21 drill to within 5/32" to the top of the bore. This should be flattened off with a "D" bit, or, if preferred, grind a No. 21 drill or use a 5/32" end mill to make a flat bottom hole.
Make the seat for the ball by the usual procedure. That is, ream the hole 3/32" with a straight or taper reamer, etc., to make sure the hole is truly round. Set 1/8" steel ball on the hole and with a short piece of brass rod and a hammer, tap the ball to form the seat.
The top of the valve chamber can be plugged and threaded 3/16" 32 or 40 threads, whichever you have. The plug should be recessed or have a projection on the end to center a medium tension spring to load the ball. A spring is required to obtain quick closing of the ball through the oil. The discharge, while shown on the sketch as coming from the back, can be drilled on either side or on two sides, one for each cylinder; or it may come out of the plug at the top by making said plug into a union fitting. The sump can be cut out with an end mill or drilled and cut out with a small chisel. When done, a 3/32" hole should be drilled about 3/8" centers from the hole constituting the valve seat. This permits the oil which drips into the sump from the reservoir to enter the bore when the plunger is at the extreme outward end of its stroke.
The plunger can be a piece of 1/8" steel, bronze, or stainless steel rod which should work easily in the bore of the pump. A hole for the connecting rod pin can be drilled to suit a 1/16" pin or other suitable bolt size. The pump can now be assembled and a little oil placed in the sump and plunger worked by hand. If made with care, it will be found that the oil being forced through the discharge cannot be held with the finger over the opening.
The sketch shows two holes drilled through the body with a No. 43 drill for use in bolting the pump to the engine. The use of this arrangement is a matter of choice and will depend on where the builder finds it convenient to install the pump on the engine. In several instances I have placed them on one side of the cylinders on a small bracket fastened to the frame. In instances where two lubricators are used, they can be placed in a similar position, one on each side. In other instances they have been placed low between the frames and the oil from the regulating valve carried down by means of a 3/16" O.D. copper pipe so that the oil may drip into the sump or sumps. The idea, of course, of the drip from the supply pipe is to permit the engineer to see the number of drops per minute going into the lubricator. The amount may be increased or decreased as desired.
Operation of the plunger should be obtained through a rocker arm from an eccentric rod being used for an axle driven pump, or a separate eccentric may be used if convenient to do so. A minimum stroke of 7/16" must be obtained. There is a temptation to work the plunger from the movement of the valve gear such as the link where Walschaert's gear is being used. I do not advise this as the extra load at the moment when oil is actually being forced into the chests will place undue strain on the gear. There is also a possibility of the cylinder receiving most of the oil due to the lessened pressure on one side caused by a cylinder port being open. This condition is not serious because the quick movement of the plunger sends the oil into the steam lines or chests at such speed that the lessened pressure mentioned has very little effect. Any doubt can be relieved by making use of two lubricators--one for each cylinder.
A check valve should be located between the pump discharge and the tee where the line divides and leads to the steam chests or steam supply pipe, as the case may be. Also, the oil lines from the dividing point should be of equal length to provide equal resistance, thus preventing hogging of the oil by one cylinder.
A small piece of brass wire screen can be rolled up and placed in the sump of the lubricator to prevent dirt, flies, or other foreign matter from going down into the bore of the pump.