Monday, 18 January 2016

Driver's Eye View

The last few weeks have been busy and I've amassed a back-blog again. Not to worry as the 'blog has had to give way to actual progress being made.
The way forward
Apparent from the above photo is the gauge glass and valves with protector, the double check valve, the safety valves and the forward-reverse and sanding levers.
Compare with this photo taken in 2005.
January 2005
One lever has disappeared so that the sanding gear only requires a single lever for both front and rear sanders. The former right hand lever used to do the off-side rear sander only. Why was it done like that? I hear you ask. A very good question to which I don't know the answer. More detail here.
January 2016
I've seen a number of photos of 7109 or the Radstock Sentinels showing huge levers in the cab. I'd always thought they looked too high and that modellers had made them too high also.
Tall levers?
I guess I was wrong. They are pretty tall!

Saturday, 9 January 2016

Chuffed (1)

Following on from my last article, Thursday 7th January 2016 also saw Sentinel 7109's boiler with 60 psi of air in it from a (somewhat fatigued!) compressor.
Boiler Pressure Gauge on cab front
The gauge gradually climbs off zero after a while.
60 psi (ish)!
Then... the regulator can be opened for the engines to turn, the cab's boiler feed pump operated, the blower blowing (it's hard to turn it off!), the whistle sounded, the steam brake operated and (blow me) 21" of vacuum on the train brake vacuum gauge.

Have a listen to this (visually not very interesting) video clip:

Does that sound good?

Streuth! I think it's going to work!

Friday, 8 January 2016

Boiler Fittings (8)

Thursday 7th January 2016 saw Sentinel 7109's original boiler water gauge glasses being fitted finally as in the photo below.
Right hand gauge glasses
I last wrote about these in April 2013 when I'd obtained replacement glass protectors and checked that they would fit. Now the valves are in for good (hopefully).
Gauge Glass Valve arrangement similar to 7109's
Having remembered to insert the new 3/4" stainless steel balls into the lower valves to reduce the amount of steam escaping should the glass tube break, I proceeded to attach the component parts to the boiler. The upright steel tube is very straight and is used to ensure that top and bottom valves are aligned accurately when the glass tube is tightened in place.
Steel tube passing down through the upper valve to the lower one
It was not that difficult to achieve the alignment which is probably down to the 

curved surface of the valve faces matching the curvature of the boiler. I'm glad that new valves with flat faces did not have to be used!
Upper valve
Not so obvious from these photos is that each valve face is sealed to the boiler using a combination of graphite gasket with suitable lashings of Rocol Steamseal.
Lower valve showing close fit around the steel tube
I was then able to put the glass tubes in place and tighten them up. The word 'tighten' here is quite subjective. Sentinel used hexagonal graphite packings for this situation as below.
Hexagonal glass tube packings (photo from Heritage Steam Supplies' website)
They fit around the glass tube and are compressed to seal the tube. However, they should not be overtightened to prevent the glass being destroyed and they should align with the hexagonal spaces within the screw clamping mechanism. One of the glasses did not seal well so I may not have got this right and will have to recheck.

But how did I know that the seal was not so good...? That will have to wait for my next article (and I promise it will be worth the wait!).

Monday, 4 January 2016

Implementing 'A Little Arithmetic'

In a recent Sentinel 7109 article, I did some 'arithmetic' to enable a new boiler blow-down valve to be fitted. The result was this elongated heavy duty hex nipple pipe fitting made by Justin Goold.
Elongated Hex Nipple
The photo below shows that it has provided the solution required and is a good, strong fit to support the substantial high-spec blow-down valve.
The Valve is firmly screwed into the wash-out plug-hole
Another view shows valve handle in its closed position. An extension handle like those used to turn-off your household water supply in the street will be useful here.
The handle is reached from the off-side
preferably with a long reach extension
Down-stream of the valve, the pipe fittings are galvanised malleable iron as there is no longer the boiler pressure to withstand.
Not a good place to be when the valve is opened!
Another hole in the boiler plugged!

Important Note: The boiler has four washout plug holes at 90 degree intervals. For washout purposes, only the three actual plugs should be used. Only under extreme circumstances should this valve and its hex fitting be removed. The result would be that it will not be able to be tight and in the correct orientation after refitting due to wear on the threads when it was tightened up previously. Thus, it has to be a fit once and leave well alone item.
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