"Notes
from the Unit Shop"
Kevin
O'Connor's advice for the beginning small scale live steamer
LUBRICATING
OIL
FOR
SMALL SCALE LIVE STEAM
LOCOMOTIVES
DISCUSSION
Small
scale live steam locomotives, their tenders, and the rolling stock that they
pull require proper lubrication of their moving
parts. This is especially true of
locomotives that have prototypical valve gear whether it is externally or internally
hung. Most high-end locomotives
have crossheads and crosshead guides as well as axle pumps that must be kept
oiled at all times. All locomotives, irrespective of price, have connecting rod
bearings, coupling rod bearings, and axle
bearings that must be lubricated. Eccentrics
that drive valve gear and axle pumps, as well as bell cranks and reversing
gear, must also be kept properly lubricated.
The locomotive's tender and rolling stock, with the exception of rolling
stock that has sealed ball bearing fitted to the axles, must also have proper
lubrication provided to axles and bearings.
All
of this lubrication must be applied and then run in a hostile environment.
The small scale live steam locomotive operates
at 250 to 300 degrees Fahrenheit, and even though the running gear is exposed to
the air circulating around it,
it
is still very hot to the touch. Too
light an oil will rapidly disappear at these temperatures. Too heavy an oil will
build up
on the surface. Dirt contamination
of the lubrication film becomes a real problem if the viscosity of the
lubricating
oil
is increased This is
especially true if the live steam locomotive is run on the ground as in a garden
railroad setting.
Those
of us who run consistently on elevated tracks have less problem in this regard,
but none of us want to worry
about
oil film failure that would lead to metal to metal contact, or attracting unnecessary amounts of grit and dirt.
I
once worked on two Roundhouse "Pooters" that had many a mile on them.
Both were poster children for the heavy viscosity
oil lobby. Both were caked with a
grease-like substance, which turned out to be cooked heavy weight oil and dirt.
What could wear was worn to its limits.
This was especially so in the valve motion components.
The Hackworth gear's
reverser, a kind of slot that a ball affixed to the valve gear runs in, was worn as well as the ball itself. This
wear was caused by the use of too high a viscosity lubricating oil that
attracted and held dirt, and then served as a lapping
compound as the ball traversed the slot with every stroke of the piston; it was
ugly.
LUBRICATING
OILS; WHAT IS NOT
For
the purposes of this discussion I am limiting it to the products best described
as petroleum (mineral) based lubricating
oils. I am aware that there are
other products on the market that lubricate, but I, with one exception, intend
to
ignore them for now. Let's start
off with the exception.
WD-40
and LPS, and other similar products, are not lubricating oils.
They are penetrants and protective products that are
designed to work their way into the smallest of crevasses (bound up threads),
displace water (spray WD-40 on your
wet
automobile ignition wires), and surface protectants to bar oxygen in the air
from coming in contact with ferrous surfaces
(precision tools) to prevent rust. They
have very little film strength and they will not produce an oil wedge in
rotating
machinery at any useful load. In
future I will be writing about the storage of small scale live steamers, and I will
be singing the praises of these products, but for now, let's avoid their use as
lubricants.
LUBRICATING
OILS; WHAT IS
All
mineral oils, which are derived from crude oil, starting with gasoline (a poor
lubricant) through kerosene, heating and
diesel oils and on up into the families of light to heavy viscosity oils that
include bunker and asphalt are considered lubricating
oils. Bunker oils and asphaltic
tars internally lubricate the screw pumps that move them from place to
place.
Diesel and heating oils lubricate the transfer pumps and injectors that
are part of a fuel supply system. Diesel
oil also
is used as a cooling fluid in mechanical diesel engine injectors.
Excess fuel circulates through the injector and
then
carries heat back to the fuel tank (heat sink) to be cooled by the air
surrounding the tank. That clear,
odorless,
tasteless
(yuck!) over-the-counter nostrum known as "mineral oil" is in fact
derived from crude oil. One of the
reasons that
it is used in the human body is because it lubricates impacted matter trapped at
the end of the line, and thus allows that
matter to be evacuated with only minor discomfort.
There
are standards that automotive lubricating oils must meet to be considered for
use in the transportation industry.
Some
standards are: viscosity, viscosity index, flash point, pour point, additives,
and Sulphur content.
Lubricating
oils
that
meet the standards for viscosity are expressed as SAE W30 for 30 weight oil and
so on for the other viscosities. Most
automotive lubricating oils contain additives that may include detergents to
prevent the buildup of carbon deposits
within an internal combustion engine, and emulsifiers that trap free water
(vapor or liquid) so as to prevent the production
of sulfuric acid in the crankcase. Neither
of these additives are needed for the lubrication of small scale live steamers.
Plain old, non-additive, machine oil is what we're after.
Actually,
after all is said and done, the selection of the proper lubricating oil is not a
hard task. Intuitively one knows
that
40 weight oil is a non-starter; it is too honey-like at room temperature; and it
"strings out" of the applicator or oil can;
it just looks like a dirt magnet! At the other end of the spectrum we have watchmaker oil (used to be sperm oil)
which
is obviously too light for our uses. Next
is sewing machine oil, which is about 10 weight.
The regular old red can of 3-in-1oil is in this league. The
next step up encompasses two similar 20 weight products; something called
turbine
oil and the "harder to find than its well known cousin," 3-in-1 electric motor oil
in the blue can. Last is 30 weight
machine oil, and it has just too much resemblance to the aforementioned 40
weight product that was previously discarded
as a candidate. At this point the
field is pretty narrow, and personal choice or product availability will probably
be the deciding factor in choosing the best lubricant.
TESTING
For
the past five years I have run my personal live steam locomotives with
lubricating oils that ranged from W10 up to and
including the sticky W40. I have
found that with regard to live steam locomotives the operating temperature of the
locomotive, not the ambient temperature of the environment dictates the choice
of a lubricating oil. Over the last
five
years I have run live steam locomotives in local temperatures from a low of 40
F (and raining) to a high of 105 F using
these various weight lubricating oils with dead-on similar results.
The one that works the best does so at all local outdoor
temperatures.
I
expected that there might be a difference in the way that rolling stock might be
affected by the choice of differing weight
lubricating oils applied to their wheel bearings as ambient temperatures dropped
in winter. At first I though I saw
a trend in this direction. I was
wrong. What I was seeing was a
reduction in tractive effort caused by the live steam
locomotive giving up heat to the colder air (black body law).
That required much higher fuel settings to maintain the
required boiler pressure to pull the same load at the same speed.
Since all the gas fired live steam locomotives that were
used in my testing either had footplate mounted gas tanks or steam heated tender
bunkers, it is safe to assume that there
was no drop of butane pressure as the outside air temperature cooled.
CLEAN-UP
All
live steam locomotives need to be cleaned up on occasion, and certainly before
storage. I will cover this clean-up
process
in some detail in another piece, but for now let's just concentrate on good
engine keeping. I clean my locomotives
by first spraying them with "water white" kerosene.
I concentrate the spray on the wheels, chassis,
running
gear, and all the machinery between the frames. I am lucky enough to have an outdoor utility sink, and once
the
kerosene has done its work, I spray it off with cold water using the sinks
handpiece. I then sit the
locomotive on the
track
and let it drip-dry. Using the
proper viscosity machine oil for locomotive lubrication make this job easy.
If too
high
a viscosity oil is used, multiple turns with the kerosene spray will have to be
employed to dislodge all the crud and
gunk
that collect on the bottom of a locomotive.
BOTTOM
LINE
After
five plus years of small scale live steam operation (two or three afternoons a
week for the last three years), and some
semi-scientific (but not junk-scientific) testing, and considering some
practical matters like availability (hardware store)
and portability (will the container leak in the toolbox?) I decided that the
best mechanical lubricating oil for use with
small scale live steamers is ..... 3-in-1, 20w, electric motor oil followed by
the third place winner, turbine oil. 20
weight oil forms a proper oil film on all moving parts. It will not evaporate at
normal live steam operating temperatures,
adding additional 20W lubrication flushes away dirt. 20W provides a protective
lubricating film without becoming
a dirt magnet. Electric motor oil contains no additives to allow it to emulsify
with water. I easily flushes away
with an application of kerosene. One can easily obtain it from Sulphur
Spring Steam Models. And once it's properly caped it
won't
leak in your tool box. Turbine oil
is OK. My biggest objection to it
is the container in which it is purchased.
The
container has a sort of "pokey spout" with an impossibly long pull-out
proboscis. The supplied friction
cap resides on
the end of the proboscis, and thus leaks at the spout/proboscis interface are
encouraged if the container is stored on
its
side. After all it is light oil and
its purpose is to flow into (and out of) small clearances.
