Sunday, 29 April 2012

200HP Pre-War Sentinel Locos (2)

The 1920s were not well known for mass production and, of its type, Sentinel 7109 was the first of not very many, only 14 in total. 7109 was actually a basic design around which variants and enhancements could be made to suit particular customer's requirements.

Two 200HP design variants were made to suit the Somerset & Dorset at Radstock where a low bridge required reduced maximum height. These were the Radstock Sentinels with their lowered cab roofs.

another pair of 200HP specials, with works' numbers 8147, 8148, was delivered in 1929 to the LNER. Eventually designated as Y10s, they were specifically intended for use on the Wisbech and Upwell Tramway.

On these, a second, front-mounted cab was added to make them capable of being driven from the front in either direction. Tramway standards of the time dictated that 'skirts' and 'cow-catchers' should also be fitted for public protection.

Twin Cab Design with Cow-catchers
Knowing 7109 inside out, I've always found these twin cab variants fascinating. In particular, being aware of what it's like under 7109's engine covers, it would not be a nice place to work! There are hot pipes and non-elbow-friendly protrusions all over the place! These locos were withdrawn from the W&U Tramway after only a short service and one can only speculate the reason. However, subsequently, they were transferred to Yarmouth docks where they gave many years' good service.

I have recently been sent a 1933 instruction manual covering the various LNER Sentinel Locos and Railcars. It includes a diagram of the layout of this Y10 double-cabbed loco. (Click the diagram to enlarge it).

General layout of both front and rear cabs
It shows how the front cab regulator lever was connected across the top of the central water tank to the regulator valve itself in the rear cab. Obviously, this loco could not be single-man operated whilst driving from the front as a fireman was still needed by the boiler at the rear.

Various identities have been suggested for Sentinel 7109 when it gets into service; however, a variant with a front mounted cab is one I had not considered until now!

Monday, 23 April 2012

A Welcome to Sentinel Drivers Club Members

Today, I noticed a sudden jump in the visits counter and then the latest copy of the Sentinel Drivers' Club newsletter "Sentinel Transport News" popped through my letterbox this afternoon.
Issue 78 Front Cover
Although I'd contributed an article to the magazine, I'd not expected quite such encouraging comments from other authors about my little blog here! Plus there are a number of suggestions to persuade readers to come and have a look.

So, if this is the first time you've found these pages, a warm welcome (and to all other readers of course!). Any text in blue is a link which may be clicked on to jump to a related page. Try clicking "A warm welcome" and see what happens!

Good reading!

Monday, 16 April 2012

Superheater Assembly Installed in Boiler

Sunday 15th April 2012 saw Sentinel 7109's superheater and boiler top-plate assembly lifted down through the cab roof and installed in its place on top of the boiler.

Before installing the assembly, a ring of ceramic rope padding was put in place where the edge of the top plate would be seated. This is to provide a seal so that when the engines 'chuff' and create a vacuum over the fire, air is drawn up through the fire instead of through the gaps at the top of the boiler.

(There is more to be figured out here due to the large gaps around the superheater piping where it passes into and out of the top plate).

White ceramic 'Rope' placed around the edge
The assembly was lowered in place and lined up front to back with the boiler's wet-steam outlet and regulator valve assembly. (Hopefully we got it the right way round!).
'Derek' taking the strain with assistance from Glyn (Photo R Williams)
(Who's the onlooker in the rather fetching orange hat?)
Down a bit (Photo R Williams)
(Who's doing the in-cab lifting?)
A Meerkat cab-roof hand signal! (Photo R Williams)
And the task was completed.
Finally at home in the boiler top
So another major milestone has been achieved after many months of preparation!

Many thanks to all who helped in the process (Trevor, Phil, Glyn, Jeff and others who I may not have spotted).

Friday, 13 April 2012

How to make an ashpan (5)

In Ashpan part 4, I'd almost completed the ashpan's flap. I wanted to add a bracket to the angle iron cross-piece to attach a chain to for raising and lowering it. (Chain links can be hooked on using any link to set the length and hence the position of the flap when used to control the primary air entering the fire).
Chain bracket welded in place
(a simple fixing hole in the angle iron would have weakened it)
The completed flap with hinges
So how does the flap work in practice?

To minimise air to the fire (and prevent ash falling out!), it is held at the highest position.

Minimum air and ash-fallout
To control the primary air flow to the fire, it is set as required between extreme positions.
Mid position
To be able to draw out the ash, the flap is released to its lowest position, i.e. flat.
Fully open.
Sentinel 7109 could be driven with the flap fully down for maximum air but Hansel & Gretel would be jealous at the result!

If it is still not clear how the flap works, try this video clip: (Also on YouTube).


About all that's left is to fit the fixing brackets in place. This will entail spending quite some time buried beneath 7109 in a pit whilst holding the ashpan in place and marking out the hole positions. When I've figured out how to do this, another ashpan 'blog article will appear!

Monday, 9 April 2012

Manual Labour? (2)

Since the last article on 'Manual Labouring', I've now got to about page 20 - some transcription can be very tedious and the worst of all is reproducing the tables in MSWord.

The Optical Character Recognition's version of gobbledygook is particularly ripe when it comes to reading the lines across a page instead of extracting the text required from each table cell in turn; the result is something that would not look out of place with other output from an Enigma machine!

So I've given up that as a bad job and just inserted some original typewritten tables as scanned jpeg images.

For example - Fuels of various types:

(Historically this is an eye opener as I doubt that many of these fuels are available today due to the closure of the UK's mining industry).

Coals for a 200HP Sentinel:

(a) Groups 1 and 2 Bitumineous Coals are mainly free burning non-caking to slightly caking and swelling. Calorific values of between 13,500 – 14,670 B.T.U.s/lb.

(b) South Wales Groups specified are similar in burning but are less volatile and contain 92 – 94% carbon, requiring a somewhat more intense draught. Calorific values of between 15,250 – 15,200 B.T.U.s/lb.

Cokes for a 200HP Sentinel:

 Manufactured Fuels for a 200HP Sentinel:

(a) With these patent fuels, it is usually found desirable to use a 1” or 7/8” blast nozzle in place of the standard 1.1/8” - 1¼” dia. nozzles.

(b) Standard fire bars are however, quite suitable.

(c) These fuels should not be stored in an open heap as they ‘weather’ and deteriorate in composition.

I'd be glad to hear from anyone who knows the present day equivalents of these fuels.

Tuesday, 3 April 2012

Manual Labour?

Lately I've been wondering why I've been struggling to write various outstanding 'blog posts. I've been pretty busy tending the 28 ton mistress, particularly to do with security issues amongst other things but no 'blog inspiration. Then it occurred to me what was getting in the way - writing itself!

Much of the enjoyment in restoration work is seeing the result taking shape but there is a more serious side when the result will be a working steam locomotive - convincing a boiler inspector and others that a competent, professional job has been done in the process. This has always been one reason underpinning Sentinel 7109's 'blog.

Sentinel Manual Front Cover (used!)
Recently Richard Nixon, drawings' custodian from the Sentinel Drivers' Club, kindly loaned me a 65 page Sentinel document entitled "200 HP Sentinel Steam Locomotives - Instruction Manual". The manual was obviously typed on a manual typewriter judging from the layout and I would guess around 1950. Despite being written for a much later twin engined loco with double gears, the usefulness of the document is not lost on me as a basis for Sentinel 7109's own instruction manual.

So, laboriously, I've scanned the whole manual with an Optical Character Recogniser to produce 65 pages of complete gobbledygook which I am now trans-scribing back into a useful form. After about four days dipping in and out of it, I've reached page 12 - no wonder my 'blog writing is taking a back seat! Normal service will hopefully be resumed shortly!

As a sample, page 1 of the manual is shown below (click it to enlarge).

Page 1
It cordially invites the reader to write in and hence become part of a fraternity of Sentinel operators. Nowadays we'd probably refer to this as a social network!

It also refers to keeping the manual to "reasonable proportions so that it can be carried readily in the pocket". Bearing in mind that it is on foolscap paper, all I can say is that, in those days, people must have had very large pockets!

The importance of the manual becomes obvious as it is written for new owners taking the loco out of its box for the first time to set it to work. It's a good read to the right person!
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