Discussion in 'Steam Traction' started by 240P15, Dec 11, 2017.
no he'll be on the left, except on a Fairlie of course.
Wozzat? Is someone plotting the first standard gauge Fairlie to be seen in Britain since the 1890's?
referring to weltrol post about uphill to Blaenau
I have often wondered ,is it the vacuum brake system that makes this odd "farting" sounds (and also other loud noises) from the GWR locomotives?
The vacuum pump makes a regular 'phut phut' noise when the locomotive is in motion.
Noooooo...it's the nearby GWR devotees talking out of their backsides! ...Flee!>>>>>>>>>
I always find that characteristic sound of GWR locos pleasing; far better than the clanking noticeable on some elderly or poorly maintained locos of the former BR regions.
Ok. Thanks for your reply.
Yes, the G.W.R locomotives must be the most "talkative" of all steam locomotives
When starting with a heavy loud the exhaust sometimes just BANG out of the chimney.
Four cone ejector if on a larger 4-6-0?
It can be the single cone ejector or the larger four cone that makes the noise, from my experience its mostly the single cone. I was told that it is the ejector over creating and the noise is the relief valve operating.
Going back to my "spotting" days, If I remember correctly ex GW locos sometimes used make said noise from the chimney when the vacuum ejector was on. Only single chimney locos though as double chimney locos had a separate "exhaust" for the ejector between the main exhaust outlets.
That is the result of very good valve events and the semi plug piston valves which give a very accurate release point.
The noise is up the chimney though & seems to occur most when the vacuum is at or near 25". It could be a slight carry over of water ?
The only train pipe relief valve is a small pepperpot on the crosshead pump.
The ticking sound from the air valves can give a useful indication of speed - always provided you remember whether you are on a Hall or 28xx (with much smaller wheels) for example!
The sound you describe as ''farting'' is usually heard on GWR locos with single cone ejectors. It's caused by the ejector reaching it's maximum vacuum it can create, so the train pipe and reservoir even out, and as there is no air underneath the air clack to keep it off it's seat, it shuts itself briefly but the ejector pulls it off the seat again. It happens in a fluttering motion, thus making the ''farting'' sound.
The train pipe and reservoir do not even out as you put it but the noise does seem to happen when the train pipe vacuum is at or v close to 25". That is not the maximum vacuum that the ejector can create but it is the maximum vacuum which the vacuum relief valve will allow before admitting air.
The sound in question can just as easily come from engines fitted with four cone ejectors. It is actually caused by the train pipe vacuum limiting valve lifting and fluttering whilst admitting air to the system and thus causing resonance in the pipe system. As rthe brake ejector can only exhaust up the chimney, the sound is transmitted all the way through to the chimney which is why it appears to come from there. It is quite often possible to detect the resonance by observing the train pipe vacuum gauge.
In passing it may possibly be worth drawing 60017's attention to the point that his beloved door wedges wouldn't be half as reliable had Collett not given Gresley the details of GW coupled axlebox bearings, as the Gresley version had a bad habit of running rather warm. And I seem to recall that the inside big ends weren't overly good until a Swindon disciple landed at Doncaster in the 50's. It's a bit like old Alen Grice said about Doncaster "Makers" plates - "The only other thing I saw with a plate that said 'makers' was the fish fryer in our local chip shop, youth!" Maybe 60017 ought to be called 'Frying Fox'?
OK! *waves a white flag*
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