Sunday, 7 February 2016

How to fit an Ashpan (8)

I last wrote about Sentinel 7109's ashpan in December 2012. In that article, I showed the fixing brackets being processed. Since then, the whole ashpan has been languishing in my garage acting partly as a storage shelf and partly just getting in the way!

February 7th 2016, three years later, it is now actually fitted to the loco (bar a few missing nuts).
In place beneath the boiler
This photo shows how it was originally - not so different!
The original (other side view) 
There is a flap for raking out the ash.
Open for emptying
It can be closed when 7109 is in use.
Closed for use
Whether the flap is also for use as a fire-controlling damper, I don't know. I need to do some more reading on the subject.

I made a small change before the fitting in that I replaced the flap hinges with stainless steel ones. The previous mild steel ones struck me as incapable of withstanding the nasty environment.

In another Ashpan article, I showed the ashpan being jacked into place. At the time, 7109 was outside with track and sleeper ballast underneath. It was not an easy working environment.

In Midsomer Norton's shed, the floor is flat and can be traversed under 7109 using a creeper trolley. This enabled me to lie on my back with the ashpan sitting on my chest. I could then lift it into place and hold it there using a spare leg whilst doing up the nuts. Fortunately I was unable to take any photos of the process. Sometimes a selfie is just out of place for a situation!

Wednesday, 3 February 2016

Certified Gauges

Perhaps not a particularly gripping subject but important all the same. Sentinel 7109 has two steam pressure gauges and a vacuum brake system vacuum gauge; all of these are 'previously owned' and far from new.

All three gauges were initially taken to Brunel Metrology Services Ltd in Paulton, near to Midsomer Norton. The vacuum gauge passed first time but the two pressure gauges failed - not what was wanted but not surprising for vintage items.

Brunel Metrology make use of the S M Gauge Company in Fishponds, Bristol, for more demanding calibration tasks. To save time, I took the two gauges to SMG myself.

In a few working days, a phone call came to say the gauges were now calibrated to within 1% so I collected them the same day.
Within 1%!
Calibration certificates have now been issued for all the gauges and one is shown here as an example.

It was a pleasure to work with both Brunel and S M Gauges and I would recommend either for gauge calibration services. Many thanks to them both for their helpfulness and rapid turnaround.

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!).
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