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ModelWorks Pride of Penrhyn Overtype Steam Lorry My Experiences steaming POP
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In the account below I describe a typical steaming of my POP. While it provides insight it should not be regarded as a "how to guide". A steam engine is not a toy and experience is needed to operate one safely. Novice steamers are strongly encouraged to obtain instruction and supervision for their first few steamings. This is best achieved by joining a model engineering club.
I start up with "half a glass" showing on the
water gauge. I don't over fill the boiler as I find the level rises as
the boiler heats up. When starting I attach a
blower to the chimney to produce a draught. This is because the tubes and chimney are so small there is insufficient
natural draught to light or sustain the fire. I use 10 Nickel Hydride AA cells. This has raised
eyebrows on the rally field but at 1.8 Amp hour their capacity is on par
with many lead acid batteries. Whilst I am waiting I oil
up. I use two oil cans, one with thick steam oil for the lubricator
and the other with
ordinary oil. Before long there is enough steam to get the engine to tick
over. While less than 10lbs is enough I usually wait until I have
around 40 on the clock. Whilst the engine is running, the steam which is exhausted through the chimney, causes more draught through the fire. Before long I have a full head of steam and the safety valve blows off. This is not unusual but it has taken me a while to learn not to panic. This was something I was glad to have reassurance form an experience steamer. The steam expelled through the safety valve represents wasted coal and water so the art is to fire POP so that a full head of steam is maintained without continually blowing off. I find this a good point to confirm that the injector is
working and using the injector when blowing off is a good use for the
excess steam. Another method of getting water into the boiler is using the
crank driven pump. This is slower than the injector but has the
advantage that it can replace water as it is used. As of
(1/5/05) I am having trouble with this beast - it sometimes refuses to
work. I believe a leaking clack valve is allowing steam back into the
pump. Even
so often I add two or three shovels of coal, one to the left, one to the
right and one down the middle. I have been fortunate enough to get
good steam coal despite the shortage but at a high price. 20Kgs costs
£10 through fortunately this is enough for several steamings. When the boiler is cold (the next day) I give
the smokebox and tubes a clean. I use a vacuum cleaner to remove the
ash that accumulates in the smoke box. It is impossible to reverse the tube brush partway and it must be pushed through until it comes completely out into the fire box. It may then be pulled back into the tube and back to the smokebox. |
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Prior
to filling the boiler I check the POP over. I pay particular attention
to boiler water feed as this often plays up. I fill the boiler using
the hand pump as this gives me confidence that it is working.
My
next task is to lay the fire. 
I keep some kindling wood in a jar filled with paraffin. I place a few
pieces of this in the fire box.
I
then light a piece of kindling placed on the shovel and shove it through the
fire door. I delay switching on the blower until now as the
draught 
through
the fire door blows out the flame as it passes through.
The
oil hole for the big ends is very awkward and requires a bendy spout.
As
soon as I have a few pounds of steam I find that I can use the steam
blower. This is a nozzle, fed
with steam from the boiler, positioned at the base of the chimney. When the steam is turned on it can
generate far more draught that the electric blower. To spare the
boiler I am careful not to use it full on at this stage. 
As
the engine block is cold the steam condenses and there is a lot of water
about. POP does not have any drain cocks but as it has side valves
this is not a problem. 
When
I open the regulator wide open I sometimes find that the draft is so fierce
that the fire is drawn up the chimney. Over the winter I made a spark arrester
from a tea strainer which works very well.
It
is soon time to pack away. I stop the engine and do not use the
blower. Without a draught the fire soon dies down and I am ready to
drop the fire. I have modified the fittings supplied by ModelWorks so
that I can use a socket to remove the bar that holds the grate.
I
drop the fire into a aluminium tray. Whilst hot, I leave all the
grate fitting in the tray but I have great difficulty in remembering to
remove them before disposing of the ashes. Several times I have had to
rummage though the ash heap look for the securing bar.
Without
a fire the pressure soon decays and when there is only a few pounds on the
clock I open the blowdown valve. The water is still very hot and the
engine is engulfed in steam. (OK steam is colourless it's water vapor really) 
POP
gets quite dirty and I like to give it a good clean before before finishing
for the day. I use warm water and detergent.
To
clean the tubes I use a 3/8" bristle tube bush (what else!). When
I first tried this I was concerned that it would get stuck so
I only pushed the brush in partway before trying to remove it. Guess what,
it got stuck. I eventually got it out and trimmed it so that it was
smaller than the flue bore. I now know better and have a new brush.