The sound of a steam locomotive

No. 6233 "Dusshess of Southerland" singing her theme song.

A lot of this typical clikking noises from 6233 at the beginning of this video. Someone who knows what they araise from?



Knut

 

Air pump?

 

Similar noises to stabled diesels at the beginning, so more than likely pressure relief valves in the air brake system blowing off. Then the rhythmic drumming of the air pump starts... I still haven't got used to hearing LMS Locomotives with Westo pumps!

Richard.

 

Auto drain valves in the air system. They automatically remove condensate that naturally occurs in air systems.

 

Thanks a lot for your explanation Steve!

Knut

 

Yes, I`ve also heard this noises on diesel locos. Thanks for your reply Richard.

 

I still find it odd hearing the pump for air brakes running on steam in the UK- some seem to be very loud compared to others- is there a degree of silencing/suppressing possible?

46100 from memory is one of the quieter ones- Bittern seemed very loud when I saw her?

Chris

 

I'm getting used to it and I even rather like it because it highlights how steam traction is being made compatible with the modern railway.

 

For people who like the sound of air brake pumps .I can recommend Transcords record ,it a 45 EP , that came out circa 1958 ,its called N7 on the Jazz. Its recordings of LNER N7s working suburban services out of London Liverpool Street. It is one of my most played Transcord records. They certainly could create a racket ,when 3 or 4 were in the station at once.
I got addicted to the tune/noise by the air braked J15 that 31A Cambridge sometimes sent(normal engine was vac brake 65390) to Kettering on the first train of the day ,it stayed on shed and worked the last train back, it could be heard puffing and panting all day long, even from a long way off.

 

Apologies for my lack of technical knowledge but snifting valves is that the similar to what they called Bypass valve? https://www.nwhs.org/qna/BypassValves.html
I think some norwegian compound engines were fitted with these.

Knut

 

Snifting valves were fitted to the steam pipes near the cylinders. When a piston valve engine was coasting with the regulator closed, a vacuum was created which would draw air and other contents of the smokebox down the blastpipe and into the cylinders, where the indrawn ash and char became an abrasive causing piston, cylinder bore and valve wear.

A bypass valve was located in a pipe connecting the two ends of each cylinder. With steam on, the valve closed so the connecting pipe was shut so there was no communication between the two ends. With steam shut off, the valve opened and allowed air into the end of the cylinder to which the piston was travelling to be pushed into the other end, thereby preventing back-pressure at one end and a vacuum build up at the other.

Slide valves tended to lift off their seatings when steam was shut off so neither of these valves were needed.

 

Thanks a lot for your information LMS2968

 

Having been born 4 months after the end of GE steam, I was never able to experience the sound of N7's in service. Right now I'd settle for hearing the one we have left working again but appreciate that the EARM probably does not have the resources available at present.

 

As usual with steam loco design, it is puzzling why some railways preferred one device over another. Bypass valves do not seem to have been particularly common on UK railways (happy to be corrected on this point) although the first five Duchesses had them initially, and apparently the Fowler 2-6-4Ts. Re the latter, Burgess mentions in his book "Working with LMS Steam" (p8) that the bypass arrangement on the 2-6-4Ts was a source of maintenance issues but after they were removed, the drivers complained the locos were sluggish. Wardale devotes a page to considering the various devices and their advantages/disadvantages ((p101) and decided on Porta's precedent to remove bypass, snifters and drifting valves from his modified 19D and 25 (SAR locos had all three devices), and drivers were instructed to drift in mid gear with the regulator cracked open.

 

Are you sure? In mid gear, wouldn't the valves be closed for both inlet and exhaust?Then no steam would flow into the cylinders but smokebox fumes and ash would be drawn in. I would expect regulator cracked open but somewhere near full forward gear.

 

Quite a number of references to be found in The Red Devil. Mid gear is correct.

 

You're forgetting lead steam.

 

When you ask if I am sure, are you asking whether Wardale knew what he was talking about, or can I explain what is happening in the valve chest? Assuming the latter, I would thoroughly recommend Wardale's book, as he sets out the thought process of re-designing the valves for the Class 26. Because of the lap and lead incorporated in the Class 26 (55mm + 6.4mm), the valve travel in mid gear is around 123mm (imparted entirely from the combination lever which, in mid-gear, is pivoting around a theoretically fixed point of its top pin, as that is fixed to the theoretically stationary radius rod). As Steve says, the valve opens to lead steam at mid gear. Wardale sets out graphs of the behaviour of standard and modified Class 25 valve gears at the full range of cutoffs and including the opening of inlet and exhaust steam ports in mid gear (Wardale notes that the opening to exhaust of the 26 in mid-gear was greater than that the maximum opening of the 25). I agree that it is the sort of thing where you would ideally like to see a large scale model of the valve operation to understand what is happening. Practical operating conditions may affect the theory which is perhaps why railways were keen on snifting/bypass/drifting devices.

 

Thanks for the explanations.
Edit: When I asked "Are you sure" I meant were you sure that that was what Wardale had said. Obviously he knew understood these matters better than any of us.