Straining the Rubbish

An earlier article has described Sentinel 7109's boiler feed pumps including the cab-mounted one on the right hand side.

Original Cab-mounted Boiler Feed Pump

The pump has to draw water from the water tank via pipework and a coarse strainer situated in a right-angled fitting and isolating valve housing just in front of the cab.

Strainer and Valve Housing by Water Tank

The picture below was taken just after Sentinel 7109 arrived at Midsomer Norton Station in December 2004. It shows how scale and rubbish accumulate at the bottom of the tank. The pipe at the bottom of the picture is the take-off for the cab feed pump. It does not suck directly from the tank bottom and so not too much detritus should be drawn. However, to be safe rather than sorry, the strainer is included. (Another in-line strainer may also be added at the pump inlet).

Bottom of the Water Tank

Since the above picture was taken, much of the scale and rubbish have been removed using a domestic vacuum cleaner (honest!) with a long hose to reach in from the top. Some chemical de-scaling may also be necessary in the future depending on how 7109 reacts to water treatment. An awful lot of Kilrock-K is needed for this type of kettle!

Coarse Strainer Housing

The strainer housing is shown above. When it was first opened, a rather distorted, vaguely cylindrical-shaped, perforated, oxidised, copper thing came out. On trying to reform it into shape, it was obviously going to break and eventually it did.

However, since it was already broken, there was no harm in at least trying to fix it.
I heated the parts to red heat and quenched them in cold water to anneal (soften) them. Then I did the reshaping using a rubber mallet, a 4lb hammer as behind support and a broom handle about the right internal diameter.

I then silver soldered the pieces together as in the picture below.

Repaired Coarse Water Strainer

Hopefully I haven't blocked too many of the strainer holes and it may work better in some orientations than others. However, I think we have a strainer capable of going back into service again!

Wrong Trousers Appeal?

For impact's sake, I couldn't resist a little mischievous colour manipulation for this posting. The item pictured below is normally found the other way up and in red but I thought it had a certain Wallace & Gromit appeal as shown.

Eat your heart out Wallace!
What about a new pair of hot-pants?

More seriously, I'm appealing to owners of Sentinel locos with the 100HP boiler to join the numbers requiring a new Funnel Base.

Sentinel 7109 uses a pair of these double chimney units mounted above the boiler inside an outer shield. One of 7109's Funnel Bases is in a poor state and needs renewal; the other has seen better days but will be serviceable for a few years yet (but it's not much use on its own!).

Twin double chimneys and outer shields

The 100HP locos with the '25% larger than standard' boilers have a single double chimney unit of this type. (Sentinel waggons have a rather different type with a longer 'bell-bottomed' profile).

Richard Nixon, Sentinel Drivers' Club Drawings' Officer, is 'in the throes of' arranging for patterns to be made for new Funnel Bases to be cast. The more required, the wider the spread of the pattern costs even if rather earlier than planned.

So, if you are reaching the stage where your funnel base will soon need replacing, please contact Richard whose Email address can be found by clicking here.

To check if this is the type that you have, a drawing of the funnel base is shown below although a better resolution version may be required from Richard. (Click the drawing to enlarge it).

Funnel Base Drawing
(Drawing courtesy of the Sentinel Drivers' Club)

No comment!

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.

However, 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!

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!

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).