What do these do.

This topic has 12 replies, 9 voices, and was last updated 27 January 2017 at 10:59 by Bazyle.

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26 January 2017 at 11:18 #25040
Eric Cox
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@ericcox50497
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26 January 2017 at 11:18 #280257
Eric Cox
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@ericcox50497
On the loco that I'm drawing up there are a few items that I'm unsure of their purpose.

The first one is pipework over the driving wheel terminating at a lidded bowl

The pipework starts on the side of the firebox

The second item is a lever on the side of the firebox

and has a linkage to the chimney

And lastly, the three items atop the boiler, the one on the right is the steam dome incorporating the safety valves. The centre one looks like a hatch to fill the boiler but what is the purpose of the left hand one atop the firebox
26 January 2017 at 12:50 #280286
Bazyle
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@bazyle
Looks to me like the pipe over the wheel is coming from an injector and so the bowl is a clack valve.
The lever may be operating a flue damper as there is a pipe above left to a blower so not that.
The secondary dome over the firebox carries the shrouded safety valve (I hope). It has the same spring arrangement as the other safety valve on the main dome. Proximity to the driver may have prompted the shroud in an unusual consideration fro not blasting him with scalding steam (after the first two drivers died)

Edited By Bazyle on 26/01/2017 12:53:00
26 January 2017 at 13:00 #280288
paul rushmer
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@paulrushmer83015
Hi Eric

I do love these old engravings they create as many questions as they answer!

My thought is the pipe and fitting is a boiler feed and the lump beside the fife box is a injector but the loco may be to old for one. As for the lever and rod to the smoke box variable blast pipe may be?

Good luck with the model Paul
26 January 2017 at 13:41 #280298
JasonB
Moderator
@jasonb
Looks like a blower to me and the lidded bowl is a tapered cock valve. You often get a blower like this on traction engines and the valve is near the chimney to discorage a poor driver from using it too much
26 January 2017 at 13:49 #280300
Roderick Jenkins
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@roderickjenkins93242
Is it possible that the central lidded box is a sand container?

Rod

Edited By Roderick Jenkins on 26/01/2017 13:55:39
26 January 2017 at 14:38 #280316
Eric Cox
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@ericcox50497
What is the purpose of the blower as suggested by JasonB.
26 January 2017 at 14:45 #280319
Scrumpy
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@scrumpy
I seem to remember on some very early engines ( as seen in etchings at York ) they fitted chimney dampers could this be along those lines
26 January 2017 at 15:56 #280332
Brian Oldford
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@brianoldford70365
Posted by Eric Cox on 26/01/2017 14:38:06:

What is the purpose of the blower as suggested by JasonB.

It allows the driver to keep some draft over the firebed when the regulator is shut. The venturi effect creates a partial vacuum in the smoke-box in a similar way to that caused by the exhaust from the cylinder.

E.g. Very useful to prevent a blow-back of fire onto the footplate when entering a tunnel whilst coasting.

Other nasties can occur when smoke-box vacuum is lost or (worse) it become pressurised.

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/411997/070130_R042007_Grosmont.pdf

Edited By Brian Oldford on 26/01/2017 15:56:44
26 January 2017 at 15:58 #280333
Brian Oldford
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@brianoldford70365
Posted by Scrumpy on 26/01/2017 14:45:43:

I seem to remember on some very early engines ( as seen in etchings at York ) they fitted chimney dampers could this be along those lines

If they did you wouldn't use them on the road. See the RAIB report mentioned above.

Edited By Brian Oldford on 26/01/2017 15:58:31
27 January 2017 at 09:30 #280495
Ian S C
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@iansc
With increased airspeed, more draught would be created, so a damper could be used to reduce the daught if required, increased draught, hotter fire, more fuel burnt. What do I know!

Ian S C
27 January 2017 at 09:47 #280502
Weary
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@weary
Hi Eric,

I suspect that the lever operating 'something' inside the smoke-box just in front of the chimney is a variable blast-pipe mechanism. These were common on French locomotives of the period, you will see it on photo's on-line of the preserved 'Crampton'.

The 'conical' structure on the firebox looks suspiciously like a safety-valve cover, if you look at the extreme left edge of the print as reproduced in your text it looks like the springs are fitted attached to the boiler and the shadow outline of the levers can just be seen. This is also a classic continental fitting of the period and can be seen on many locomotives as that type of boiler has a large steam-space at that point.

As to why under this hypothesis there are two sets of safety valves shown –>

The locomotive is rather idiosyncratic so may be a feature of the locomotive.

Maybe an error in the drawing! (Not that uncommon.)

Regards,

Phil
27 January 2017 at 10:59 #280519
Bazyle
Participant
@bazyle
The blower is mostly used during initial raising steam as full size can't use the 12v fans we use on models. Then it is used in the station or otherwise stopped to keep the draught going through the fire. The effect without the blower on the fire is quite dramatic, it practically goes out. bear in mind you have a fire 100 times bigger than a domestic living room one and a chimney only ten feet high not 40 so natural draught is non existent. When running the exhaust steam is used instead.

In the engraving the blower feed is seen as a pipe entering the chimney base and is fed from the rear steam dome by a conical valve just above the lever that was also asked about.
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