Lubricator Design I
Nelson Riedel, Nelson@NelsonsLocomotive.com
10/03/2005, last updated 11/02/2005

The later Heisler locomotives used mechanical lubricators to supply oil to the many sleeve bearings and displacement  lubricators to supply steam oil to the engine steam cylinders and compressor steam cylinders.       

The photo on the right shows the mechanical lubricator on Cass 6.  The cab is off so it's easy to see the lubricator.  The group of small tubes are some of the lubrication feed tubes.  I counted the number of feed tubes but either didn't record the number or forgot where I recorded it.  There are probably between 20 and 40 feed tubes.
This photo shows the displacement lubricator on Cass 6.  MRSR91 used a similar if not identical lubricator.
This is the mechanical lubricator on MRSR91. It is attached to the left side frame stiffener casting.   The many oil feed tubes go out the back of the lubricator.  It's possible that there was a second lubricator  at some time which coupled to the shaft that extends out the side of this lubricator.
This photo shows the linkage that drives the MRSR91 lubricator.  The linkage goes under the lower frame bar and connects to the rear eccentric strap.
The only photo I have of the  link that connects to the eccentric strap is of Cass 6 shown on the right.  The connection seems to be to one of the bolts that holds  one of the eccentric rods to the eccentric strap.

I built a mechanical lubricator for the shay and and am very pleased with it now. However, along the way I had persistent problems with the output check valve leaking and and a problem with it supplying too much oil.   When the check valve failed steam backed into the lubricator and forced much of the steam oil out the reservoir vent hole (a mess).  The oil that wasn't forced out turned to grease which had to be cleaned out before the reservoir was refilled (a worse mess).   I finally added a second check valve using an O-Ring on a poppet.  This second valve fixed the problem.  The too much oil was in part due to a calculation error.  The lubricator was driven by a ratchet arrangement so that the only way to adjust the flow was to reduce the piston diameter or to reduce the stroke by making the piston shorter.  The message from this experience  is to use good check valves and to make the pump output adjustable.

The plan was to make a mechanical lubricator for the steam cylinder oil.  The main difference from that used on the shay would be to follow Dick McCloy's suggestion and use a roller clutch drive arrangement that is simpler than the ratchet and is also adjustable.  When designing the cross compound air compressor  I realized that lubrication would be required for the compressor steam cylinders (steam oil) and it would also be nice to be able to get a little lubrication to the compressor air cylinders (lubrication oil).    I could use a displacement lubricator for the compressor steam cylinders but they are a pain to fill.  I could also use a mechanical lubricator driven by the engine.  The compressor steam cylinder should require much less oil than the locomotive cylinders.  However, over oiling the compressor probably wouldn't cause a problem.   I started to count outputs --- three for steam oil (two for engine cylinders and one for the compressor).  It'd be nice to be able to lubricate the compressor air cylinders but that would be regular oil.  If I had a pump for regular oil, it would be nice to automatically lubricate the main bearings (two) the rod bearings (two) and the crosshead guides  (two).  All the other bearings are sealed ball bearings except for the side rod bearings and the little sleeve bearings in the universals all of which will be equipped  with grease fittings.  Grease should last for an all day run.  So --- a mechanical lubricator with three steam oil outputs and seven lubricating oil outputs would permit once a day lubrication and the engineer would only have to worry about fuel, water and food.

The next question was, could I build a relatively small lubricator with the ten outputs?  I'd also want each output independent, adjustable and with a high quality check valve, hence ten separate pumps would be required.  

While thinking of possible pump designs I remembered the pump pictured below that is used in the Triumph TR6 overdrive unit.   This pump provides a pressure of about 450 psi.           

The eccentric on the left side is mounted on the main shaft between the gearbox and the overdrive unit.  The next piece is the eccentric strap, a thin aluminum casting. The pump piston is the short rod attached to the eccentric strap.  The piece to the right of the piston is the pump cylinder.  The disk with the hole, the ball and the spring together form the output check valve.  The bottom plug is at the far right. The cylinder fits in a hole in the overdrive housing casting.    The thing I want to copy is the eccentric ring & piston with only one pivot point.

Check  Valves:  A poppet  type check valve proved to be an excellent choice for the  shay  lubricator so looked to see if I could find an economical  commercial check valve for the steam lubrication lines.   The sketch on right shows the Clippard MCV-1BB poppet check valve. These valves cost about $4 each and are rated for 300 psi and 230 degrees (Buna-N seal).  The valves are also available with Viton seals at a slightly high price.   The nominal cracking pressure is 1/2 psi.  The inside structure of the valve is shown at Check Valve Designs.
This shows the dimensions of the MCV-1BB.   One end can screw onto the bottom of a  pump cylinder.  The other end can be turned down to 3/8"  and threaded 3/8- 24 for a 3/16" OD tube compression nut.
The pumps that supply lubricating oil to bearings don't have to overcome the steam pressure so  the smaller Clippard MCV-2 Duckbill check valve show on the right can be used.   The inside structure of the valve is shown at Check Valve Designs. The output end can be threaded 5/16-24 for a 1/8" OD tube compression nut.

Clevis:  Dick McCloy showed me one of the Clippard RC-0581 clevis matching the drawing on the right and suggested it  might be useful on brake linkages.   I immediately realized it would  also be useful to link the lubricator piston and eccentric ring.  The piston can be threaded 5-40.  The piston stroke adjustment can be made by screwing the piston into or out of the clevis.   The drawing on right was scanned from the Clippard catalog and can be downloaded from the Clippard website.

Pump Assembly:  The drawing above shows several views of the lubricator pump assembly with the eccentric at various angles.  The inside height of the tank is assumed to be 2 inches and the tank floor assumed to be 3/16" thick.   Clippard sealing washers  will be used between the cylinder and top of the  tank floor and between the check valve and bottom of the tank floor to seal both the hole in the tank floor and the cylinder- check valve joint.  The clevis will be shortened to 0.437" to give a little more room for the cylinder.       

Tank: The assumption to this point was that I'd make a long eccentric to drive all the pump units aligned in a row.  The check valve outside is 3/8" hex  with a maximum width of ~0.415" which means the closest two pumps can be spaced is about 1/2" and still have room for a 3/8" socket to tighten the valve.  A single row of 10 pumps would require a tank about 6"  long.   That's probably longer than the space available on the left side frame stiffening casting.    The tank on the shay lubricator is 2" square and 1.5" high.  The best alternative seems to be to have two eccentrics side-by-side.    That would allow a tank size of about 4" long, 2" wide and a little over 2" high.  Such a tank would be maybe twice scale size but would have roughly the same shape.   The two eccentrics would be linked by small spur gears.   (This configuration was arrived at after much thought and many sketches.)

Piston: Based on experience with the shay,  a 1/8" piston diameter pump piston  with 1/16" stroke past the holes in the side of the cylinder is roughly the correct size for the Heisler.  The Heisler is larger and using superheated steam so it will require more oil per cylinder.  Each engine cylinder will have its own pump unit so that will give twice the oil.   The sliding clutch should allow the pump eccentrics to turn at half the speed of the eccentric on the shay pump so that should slow output a bit (recall that I had too much oil with the Shay lubricator).  The plan is to have a total piston stroke of 3/16".  The maximum useful stroke below the input holes is probably 1/8" which allows twice the 1/16" stroke used on the shay.  At the other extreme, the useful part of the stroke can probably be cut to 1/32" and still have reliable operation.  

Based on the above, it can be assumed that the lubricator speed can be adjusted to give the desired amount of oil to the engine cylinders using a pump piston diameter of 1/8" and and 1 /16" useful stroke,  What can be guessed about a proper adjustment for the other outputs?  The compressor should run much less than the main engine so it should need much less oil.  The engine bearing surfaces are much smaller than the steam cylinders and are not constantly washed by the steam so they should also require  much less oil.  (My lubrication philosophy is to provide the maximum amount of oil without making an intolerable mess --- and I'm pretty tolerant of messes).   The output of these pumps can probably be reduced to an acceptable rate by reducing the useful piston stroke to about 1/32".

Seals: No seals (rings) are required on this type of oil pump.  The piston is made a close fit in the cylinder and the high  viscosity of the oil makes the seal.   

Clutch: Steel Needle-Roller Clutch Bearings can be obtained  from McMaster Carr.  The smallest bearing they have is for a 1/8" shaft but it is available only with an Acetal Cage that is limited to 200 degree F.  A bearing for a 3/16" shaft would have been ideal but they don't have one.  The next larger size is for a 1/4" shaft and pictured on right.  It is 7/16" OD, 1/2" long and has a nylon cage that is good to 248 degrees F.   Two of these clutches are required, one on the drive lever to advance the shaft and one fixed to the tank to prevent the shaft from rotating back.

Shafts & Bearings:  A hardened & ground shaft is suggested for the shaft used with the roller clutches.  These shafts are available from McMaster-Carr.  The other shaft can be mild steel or drill rod..  Standard sleeve bearings will be used for three of the shaft bearings and the fixed roller clutch will be the fourth shaft bearing.

Gears:  Light duty molded nylon gears available from McMaster-Carr can be used to couple the two shafts.  The 32 pitch 22-thooth gear with a 11/16" pitch diameter will work.

The drawing above shows the lubricator pump configuration.  The tank is divided into two sections.  The section on the right with 4 pumps is for steam oil (one pump is extra but may be used for a steam powered water pump).  The protrusion in the upper corner of the left side houses the fixed roller clutch.  The gears are on the right side of the tank divider.  The shafts and sleeve bearings are not shown and the eccentrics are not shown in the top view.

The boring drawings and assembly information is in Part II.