Yeah, but why not? Pretty on topic for this group, and the quality of
his photos sure made it worth a look.
Anyone else notice the slotted attachment holes on the two scales of
that steam thermometer? Must have been how they tweaked the calibration,
at least at one temperature point.
I assume the glass stem on that style of thermometer has to make a right
angle turn at the bottom. Never thought about that one before...
I wonder if the threaded cap on that thermometer adaptor kept oil or
another liquid (used for thermal conductivity I guess?) from spilling
out when it wasn't attached to the thermometer.
That is a nice indicator set, typically you only see 1, not 3. I wonder why
3? I could understand 2 for making both front and back cards at once, but 3
hmmm.. Typicaly they would just have 2 sets of valves on the front and back
sides of the piston and make the front and back card on the same drum
(usually even on the same card) by closing one valve and opening the other.
The trouble with that is the diagrams are mirror images.. With 2 drums you
could run one 'backwards' and get the diagrams going 'the same way'...
easyer to compare...
Its for a triple expansion engine, one card writer per cylinder. The pen is
pushed up the cylinder by pressure in the cylinder and the card is rotated
by a string that connects to the cross head. The result is a plot of
pressure vs. displacement . Integration by the planimeter gives horsepower
after a few calculations.
Tom, Never thought about doing a tripple expansion engine, interesting idea.
I'm quite aware how they work. I've actually done this 'modern day' with a
'scope and presure transducer'... One of my ongoing projects is building a
rig out of a single chip micro and 4 transducers to send the info in a
serial stream to a laptop on a riding car.
The item in the case with the purple velvet lining is an
integrator, which sums the area under a curve by tracing the outline of
it while the little wheel slides on the paper.
I believe that it *does* belong with the set, as the set's
function is to draw a "card" relating pressure in the cylinders to
piston travel, and by integrating that card, you can calculate the power
developed by the piston. (Taking into account the active area of the
piston (e.g. minus the con rod area), and the piston stroke, as well as
the full scale value determined by which spring set you screwed in.
I don't have a need for the set -- but it still is somewhat
tempting. However -- I'll leave it to someone who will *use* it, and
not muddy the waters in the auction.
P.S. As for spelling gauge/gage -- both are common, and anyone who
might think to look for this on eBay should check under both
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"DoN. Nichols" wrote: (clip) The item in the case with the purple velvet
lining is an integrator, which sums the area under a curve by tracing the
outline of it while the little wheel slides on the paper. (clip)
I was not able to find the picture you are referring to, but you are
essentially correct. The area inside the loop on the card, multiplied by
the right scale factors, represents the energy in a power stroke. If you
divide this area by the length of the stroke, you get the "mean effective
pressure." The only correction I will offer is that the thing you call an
"integrator" is usually called a "planimeter."
His comment concerned the incorrect spelling of
"gauge" as "guage". The spelling variation "gage"
wasn't mentioned ... which is curious as I would
have thought that the latter was the more common
American spelling (as opposed to the
British/Canadian/Australian "gauge" ).
It raises a point though. Whenever I'm searching
ebay for something I'm seriously interested in, I
try to imaging all the common mis-spellings that
might fit and include them in the search. I've
quite frequently turned up additional listings
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