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"Notes from the Unit Shop"

Kevin O'Connor's advice for the beginning small scale live steamer


Getting Started with Frank S. 

Part One of a series on tapping the maximum potential of a Gauge 1 locomotive


Anyone who has spoken with me or who has read my previous articles in Steam in the Garden knows that my favorite small scale live steam locomotive is the LGB / Aster rendition of the WWII German Army’s narrow gauge field locomotive, the Frank S.  Aster manufactured over 3000 Frank S. steam locomotives for LGB, staring in 1989.


All Frank S. are identical except for the “O” rings used to seal the steam and butane valves.  Some units have red semi-flexible “O” rings while the majority are fitted with semitransparent soft “O” rings.  Many units will have a very tiny black “O” ring fitted to one or both of the piston valve spindle’s front end.


Quality control is excellent except some units were delivered without the crosshead guide retaining screws being installed. (for a field repair see footnote #1).  Also the rear tender axle tends to lightly bind in the bronze bearings as they are fitted to the cast tender chassis and constrained by the brass belly pan.


Lately a couple of asthmatic Frank S. have shown up at Unit Shops with poorly fitted piston ring end joints and worn out piston valve bores.  All of these observations are minor and almost nit-picky in light of the overwhelming quality of the locomotive in general; especially if one considers the price that a Frank S. can be had for, either used or new, in todays market.


Most of the telephone calls to me and the personal discussions that I have had with Frank S. owners at West coast steamups have concerned the proper operation of the Frank S. locomotive.  The LGB instructions provided with the unit overstress the safety aspects of the locomotive’s operations, while at the same time going lightly over the real work of model engineering operation and maintenance.  My goal in this series of articles is to fill in the blanks for the first time purchaser and to challenge some of the current wisdom of the small scale live steam locomotive community. 


In the original LGB instructions sheet, there is one point to ignore at all costs (or it will really cost you $$ in repairs).  That section is the one on steam lubrication.  LGB does allow the use of internal combustion (IC) lubricating oil as a stopgap lubricant.  DON’T DO IT!  Locomotives are external combustion (EC).  IC lubricants contain additives such as detergents and emulsifiers that are poison to steam powered reciprocating or oscillating engines.


Your automobile engine uses water for cooling only.  In normal IC operation the water and oil never meet up with each other, but in a steam engine lubricating oil is fully and purposefully introduced in the steam flow from the boiler to the engine.  The IC engine oil will reach out for the water and capture it in an emulsion.  If there is sufficient water available the IC engine oil will turn the consistency of mayonnaise and exhibit the lubricity of same.  This will lead to some very interesting patterns of in what used to be the reciprocating parts of your locomotive, such as the piston valve bores. 


In an IC engine the detergent factor is important to keep the piston rings, both compression and oil control, free from sticking in their respective grooves due to the elevated temperatures of combustion which will coke them in place.  A steam engine does not operate at anywhere the same internal temperatures, especially in small scale, and so a well lubricated piston ring, O-ring, or string packing will not normally stick in its groove.


The use of IC lubricating oil in a piston valved locomotive such as a Frank S. is death for the piston valve assembly.  Piston valves in small-scale live steam locomotives are generally avoided in the best of cases because of the wear factor inherent in their design.  Aster designed piston valved locomotives such as the K-4 Pacific or the Hudson or any type on which the prototype used a superheater with a “D” valve assembly.  The reasons are clearly laid out in their catalog’s section on design criteria.  I recommend that everyone have the Aster catalog in his or her collection for frequent consultation, even if there are no Aster locomotives on your line’s roster. 


The point to be made about piston valves is that they only wear out.  “D” valves will continue to remain steam tight for the life of the locomotive.  Because of this disadvantage of piston valve design, their proper lubrication is paramount in order to prevent undue wear.  PLEASE, USE NOTHING BUT STEAM OIL IN YOUR FRANK S. IF YOU WANT A FINE AND RELIABLE RUNNING LOCOMOTIVE. 


Now that I’ve beaten steam lubrication to death let’s get on with a proven method to get a Frank S. into steam with a minimum of fuss and frustration.  The methods and techniques that I will present in this series on the Frank S. are applicable to any small-scale live steam locomotive, but they are only one interpretation of many now in use.  I feel confident that they work because these are the procedures that I use each time I steam my locomotive.  I invite constructive criticism and positive input from others in the small-scale live steam community with regard to new data aimed at furthering the hobby and the knowledge thereof. 


The first order of business is boiler water.  The only acceptable boiler quality water is DISTILLED WATER, period. Even using distilled water will not prevent some mineral deposits from being formed in the boiler and the steam delivery piping and valves.  At the end of each running session, or once a year, or any regular interval that suits your schedule, it will pay to fill the boiler with a mixture of ½ distilled water to ½ white vinegar and to steam the locomotive light engine (no consist/rake).


Use the same mixtures for boiler make up and operate the engine for about one hour.  The weak acid in the vinegar will dissolve the mineral sale deposits in the locomotive’s team generating and delivery systems and you will be good to go for some time.  After the locomotive cools, drain out the remaining mixture, refill with straight distilled water, and run the unit under load till the “kitchen” smell dissipates.


The proper boiler water level in the backhead sight glass for a cold locomotive is ½ glass.  Water expands as it is heated and ½ glass will translate into ¾ glass by the time steaming pressure is reached. 


Frank S. has an operational stream dome located in the cab from which steam is drawn for motive power.  Even so, if the boiler is filled over ¾ glass, the locomotive will prime and spray a considerable amount for water out of the stack, especially on the first run out of the yard.  The forward motion of the locomotive contributes to this priming by forcing the free surface of the water in the boiler rearward as the locomotive accelerates.  This phenomena lessens as the locomotive reaches operating speed.  Unnecessary priming should be avoided at it puts undue strain on the Frank S. running gear due hydraulic lock in the cylinders which will, over time, loosen the two mounting screws affixing the cylinder assemblies to the locomotive main frame.  Using Loctite® on these two screws will prevent their unscrewing, but the unnecessary force due to priming has to be absorbed somewhere. 


The next requirement is lightweight lubricating oil for the running gear and the valve motion.  Many people use 3 in 1® oil, the stuff in the red can, for this purpose.  My personal feeling is that this oil, viscosity unknown, is too light in weight for the job of lubricating small-scale steam locomotives.  My esteemed colleague, Mike O’Rourke of Berkeley Locomotive work fame, has been using the 3 in 1 oil formulated for electric motors to lubricate his Crickets.  It is available in a can similar to the regular 3 in 1 oil, but it is in a blue can, not a red one, and its viscosity is advertised as 20 weight.  I have been using it for years with excellent results.  It clings to hot running gear yet cleans off readily with kerosene and / or 409® spray cleaner.  I believe that the stuff in the red can is more of a solvent, and have very little faith its in lubricating capacity at elevated temperatures.


The lubricating technique that I follow is the “roll over” approach.  I place the locomotive on its side and start to apply 20 weight 3 in 1 electric motor oil to all the pivot points in the valve motion as well as the crosshead guides and piston rods.  When the first side is done, I roll the locomotive onto its back and carefully lubricate all the rotating parts including connecting rods, wheel bearings, and reverse linkage.  Next I roll the locomotive onto its other side and repeat the first step. 


While the oil is finding its way into the works, check the tightness of all screws that you can reach.  The ones that are most likely to loosen are the ones on the rotating or reciprocating parts, but the real foolers are the ones that are nominally fixed in place such as the cylinder attachment screws and the two screws that hold the tender’s belly- pan in place. 


Wipe off the excess oil from the locomotive’s exterior, as anything you can see will probably not lubricate anything, but will attract and capture dirt.  Don’t forget to lubricate the tender’s four axle bearings as well.


While lubricating the tender bearings check to see if both axles rotate freely.  I have noticed that the rear axle on a number of Frank S. tenders tends to rotate less freely than the front axle.  I traced the condition to the way that the bearings fit into the rear axle-bearing slot, which is cast into the tender chassis.  When the belly pan is securely held in place by the two attachment screws, enough force is exerted on the wheel bearings to slightly misalign them, causing the rear axle to bind. 


There are three approaches to fixing the problem: open up the bearing’s inside diameter, turn down the axle’s outside diameter, or file out the slot in the chassis.  I elect to turn down the axle's outer diameter by one or two thousandths of an inch or until the bind disappears. 


The wheels have to be removed from the axles for this operation, but there is a side benefit to be realized in having the wheel sets accurately gauged in reassembly.  Look inside the frames of the chassis and inspect them for wear marks caused by wheels rubbing on them.  This condition is caused by either or both of the wheel sets being over gauge and / or the tender axle bearings not being in the proper proximity to the inside of the wheel sets.  Take a look at sketch # 1 for a view of the proper setup of the tender wheel sets.   


The last lubrication point is the steam delivery system oiler located on the reversing lever side of the locomotive.  Unscrew the oil tank’s fill cap.  A new locomotive will have an empty tank while one that has been run will contain condensed water and some steam oil.  The tank can be sucked out with a plastic syringe or a disposable plastic pipette obtained in bulk (cheaply) from a hospital supply house. 


While the oil tank is empty fill it with steam oil, (not IC oil), that has been obtained from a reputable supplier (Sulphur Steam Models, Willow Works, Brandbright).  There is a choice of “thick” or “thin” (viscosity) steam oil, but I really don’t think the difference is important in our scale of operation.  The steam lubricating oil tank is mounted so close to the boiler that its operating temperature varies too little to worry about viscosity, but I do worry about usage.  Aster locomotives are notorious for their consumption of steam oil in operation.  More may be better, but too much is a mess, and I’d rather have the oil in the works and not on the locomotive’s boiler casing. 


My approach is to soft solder the oil tank’s delivery pipe inside diameter closed and then redrill it with a bit ½ the original diameter (.020, #76).  This restricts the flow of steam oil so that the locomotive runs cleaner and has the potential to run longer.  My lead Frank S. will run almost an hour on one charge of fuel and this modification gives peace of mind in the lubrication department. 


When you fill the steam oil lubricating tank, leave a little (1/16”) air space to compensate for thermal expansion.  This initial airspace allows the Roscoe type oiler to do its job more efficiently. 


Let’s fuel up!  Any of the butane, isobutene, or butane/propane gas products on the market can be used successfully in the Frank S.  Propane is a no-no because of the copper gas tank in the Frank S. tender is not safe for use with that fuel.  When copper, either drawn tube or rolled flat stock, is heated to the temperature necessary to silver solder (1200˚F to 1500˚F) it becomes annealed whether the part is quenched in water or not.  This annealing process removes all the work hardening inherent in the part thus reduces its available tensile strength to that of unworked copper.  This loss of strength in the Frank S. gas tank is the reason that Aster / LGB forbids the use of a high potential mechanical energy gas (propane) as a fuel. 


The butane fill valve on the fuel tank is of the self-venting variety.  This means that it is not necessary to vent the tank of gasses by way of the fuel control valve at the other end of the tank.   You can prove / test this principle by pressing down on the filler valve nipple with a pencil eraser and noting that, even though no liquid fuel is being delivered to the valve assembly, gas escapes from around the nipple via the slot milled in the valve body top. 


To fuel the gas tank invert the container of the fuel of choice, align it in as straight a manner as possible with the center line of the fill valve, and push down firmly.  The filler connection should not leak any liquid gas, but there will be a hissing and some vapor emanating from around the filler nipple in the area of the milled slot: this is gas escaping from the container as liquid gas enters and displaces it. 


In order for this transfer mechanism to work there must be a difference in pressure between the storage container and the fuel tank.  Butane, like all gasses, will only flow from one container to another when there is a pressure difference between them. This can be accomplished in one of three ways: raise the pressure of the delivering container, lower the pressure of the receiving container, or do both. 


The lowering of pressure of the receiving container is a given in the transfer equation due to the action of a properly venting receiving tank fill valve.  Raising the pressure of the delivering container can be accomplished by placing it in the rays of the sun between runs, keeping it indoors on a cold day, or placing it in a container of warm (90˚F to 110˚F) water.  Gravity has nothing to do with the flow of fuel except that the storage tank must be inverted in order that liquid, not gas, flows from one pressure vessel to the other. 


Continue to firmly push down on the storage container while noting the flow of gas vapors from around the filler valve nipple.  At some point a gush of liquid gas will appear round the nipple.  This is the signal that you are done with filling the tank. 


A word of caution at this juncture!  Do not permit any open flame to be present during the fueling operation.  This includes nearby passing small-scale live steamers.  As acquaintance of mind singed his beard at a steam up when an Americanized Mogul on the mainline passed his sidelined Bill just as he topped off his butane tank.  Vavoom!!  I jumped a foot and learned a lesson. 


When you get that gush of liquid gas pay particular attention as to just where it comes from.  It should be from around the filler valve nipple: not from the connection of the storage tank filler to the filler valve nipple.  This is the reason for 99% of the short duration runs experienced by gas fired locomotives.  If the flow is from around the connection disturb the connection and start again.  Repeated practice and attention to this detail will improve your fueling skills.  Take a look at sketch #2, which illustrates just what a butane tank looks like in cutaway.  At this point our Frank S. is watered, lubricated, fueled and ready to be put in steam.  Let’s do it! 




Footnote #1.

Frank S. engineers need to be aware that the crosshead guides, on which the crossheads ride and upon which they depend for proper piston rod alignment, are not secured at the forward (rear cylinder head slot) end.  Factory drawings show a m2.5x4 slotted head machine screw at this location, but the production engines seem to lack them.  Movement of this guide in the vertical will lead to excessive wear of the silicone o-rings in the piston rod gland, and cocking of the piston/piston rod assembly.  This condition can be easily corrected by taking some .010 or .015 diameter brass or copper wire and reeving it around the cylinder piston rod glands nipples and the end of the guides two turns, pulling it tight and twisting the ends together.  Cut off the excess twisted wire.  Two or three twists will do just fine. 


This series of articles were originally published in Steam in the Garden.  Appreciation is expressed to both the author, Kevin O’Connor, and Ron Brown, Publisher/Editor, for permission to post to the SouthernSteamTrains.com web site.


Part Two offers advice on making a good engine even better!




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