Re: starting a steam loco

On 8 Oct, 13:49, "R.C. Payne" <rc...@xxxxxxxxxxxx> wrote:

I am familiar with the mode of operation of this (Newcomen) type of
engine, but I would query the statement, "Steam was allowed to rise from
the boiler into the cylinder". I would have thought some sort of
positive induction would be needed to get the steam to displace the air
that would inevitably leak into the cylinder when the engine sits idle
for some time. I can see one option being to lift the weight[1] (or
halt the engine with the weight in the raised position and have a catch
to hold it there in order to start the engine next time)

You've raised a good point here, and I'm not sure of the answer. If
you start with a cylinder full of air. I would have thought that you
could get some steam into it simply by the fact that it was suspended
over the boiler, so it would contain a mixture of air and steam. If
you were to condense the steam, you would create some drop in
pressure, though far from a vacuum, and the piston would move down,
until the pressure of the air underneath it in the cylinder was equal
to the pressure of the atmosphere above. If you then opened the valve
this would allow the condensate to run back into the boiler; the pump
rods would fall, raising the piston, and this would draw in fresh seam
from the boiler; rather more than found it's way into the cylinder on
the first stroke, and so the piston would be moved down further when
the steam was condensed, which would allow it to draw in still more
steam on the third stroke etc., until after a few strokes the engine
would be working the full length of its stroke. Does this sound
reasonable?

.

Relevant Pages

  • Re: Boiler explosions and gradiants.
    ... In the later years of steam, boiler explosions due to structural defects seemed to have almost become a thing of the past. ... Reading about such accidents gave me a much deeper appreciation of just why boilers need to be so well inspected and refurbished so regularly. ... Drivers on preserved lines probably know their engines and their requirements as well as any BR driver ever did, but what about when out and about with a relatively strange engine on a relatively unfamiliar route? ... The fact that these incidents continued to happen well towards the end of steam tends to suggest a depressing inevitability about this kind of human error once in a while. ...
    (uk.railway)
  • Re: Steam powered cars (alternative)
    ... Boiler, engine, condenser all make the steam engine much more bulky ... under the Simple Pressure Vessels Regulations 1991. ...
    (uk.transport)
  • Re: starting a steam loco
    ... engine, but I would query the statement, "Steam was allowed to rise from ... the boiler into the cylinder". ... over the boiler, so it would contain a mixture of air and steam. ...
    (uk.railway)
  • Re: live steam models
    ... >>> I just picked up a Jensen Model 25 steam engine with electric boiler. ... >Is this oil added to the boiler feed? ...
    (rec.crafts.metalworking)
  • Re: Be careful what you ask for
    ... Apparently what we're looking at here is, basically, a modified steam ... But a steam engine has combustion, ... efficient on the car, and pollutants that come out of the car. ... weight of cooling and forced draft fans, fans, and boiler feed, ...
    (rec.arts.sf.fandom)