Steamy!

48 years since Sentinel 7109 was last believed to have been steamed (and 56 since it was definitely known to have been steamed), finally a fire has been lit in the grate of this unique double-engined Sentinel locomotive.

Steam rising

(Also on YouTube)

An early start on Tuesday 9th Feb. 2016 saw Andy Chapman, Nigel Dickinson and Graham Findlay (with a cameo appearance from Justin Goold) applying the match at 08:30am.

Oily rag activity

Activity began slowly.

Slow start

A whimper from the rooftop:

Fumes fuelled the fire

Raging inferno in the making

With commensurate reaction from above.

Quadruple chimneys' worth

And more fuel for the fire.

A handful of coal

With more reaction from above.

Close atmosphere developing

Not such a cold day after all.

A nice fire to sit by

But getting a little foggy inside!

A real pea-souper!

Inevitably a new machine brings its own noises. The cab-mounted Worthington-Simpson steam driven water pump gets some exercise - what a wonderful sound! (Also on YouTube).

A brilliant day of progress and a joy to see and hear 7109 coming back to life with enthusiasm!

Note: water hoses and fire extinguishers were close at hand during the whole operation.

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!

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!

Boiler Feed Plumbing

On the shortest day of December 2015, Sentinel 7109 received another milestone of reassembly.

Twin Check Valve unit with single check valve to the right

The pipework connecting the two engine-mounted water pumps to the boiler's twin check valve was completed. The single check valve used with the cab mounted pump is in the shade to the right. (A check valve allows the water to only flow in one direction. Hence, water can be put into the boiler without it coming straight out again!).

The twin valve takes water from each pump but allows it to be recirculated to the water tank if not needed by operating the red handles. This is important because the engine pumps are always working when the loco is moving.

I'm really pleased with this pipework as it is original but was not fitted when the loco arrived at Midsomer Norton in 2004.

Remote Control - 1927 Style in 2015

I began this small series three years ago here. With due regard to health and safety, I did not complete the construction as there would have been a trip wire to negotiate at the same time as squeezing into the right front corner of the cab where most of the vacuum braking and safety valve apparatus was being made resident. (I've lost count of the number of times I've had to breathe in very deeply to avoid impaling myself on the safety valves and vacuum gear).

The trip wire is now in place ready for the unwary (probably me on bad day!). There is a lot more to go in this corner and much not obvious in this photo.

Trip wire in place

Below the cab floor, the cable attaches to the exhaust condensate valve. (Also shown here is the new stainless steel braided (High-tech!) mechanical lubricator feed pipe to the regulator steam supply).

Underneath end of the remote control cable

The cable passes through the cab floor by the vacuum pipe.

Through the cab floor (1)

The two water feed pipes from the engine-mounted boiler feed pumps are showing - and still need to be linked to the boiler. The cable looks as if it will rub against the water pipe. Some care will be needed here.

Through the cab floor (2)

From a different angle:

Through the cab floor (3)

Looking at the photos in the earlier article, it brings home just how much has been done over those three years (and that the amount still to do is looking a lot more encouraging!)...

Working Under Pressure?

I've been fitting the boiler pressure gauge lately. It's red lined at 275psi and we have an original Sentinel type.

When I came to fit it, it seemed a good idea initially to adopt the alfresco approach as in the photo below.

Visitor-friendly alfresco pressure reading

One bright spark suggested that I ought to add wing mirrors so that the driver and fireman could also share the experience!

This leads me onto the point that the gauge does have to be visible by both driver and fireman so this mounting position is as good as it gets - so long as it's mounted on the inside!

Driver's eye view

OK, so some daftness has crept in here. In actual fact, it's more sensible than you might think. To drill and tap the M6 fixing holes through the cab front from the inside is not easy at all as the boiler is in the way. However, if one small hole is drilled through, the rest of the drilling and tapping can be done much more easily from the outside.

Fireman's eye view

Bearing in mind that there is a top cover to add height to the boiler, the gauge is still visible from both sides of the cab.

Safety Valves (2)

My last look at Sentinel 7109's safety valves was about two years ago. Then I'd initially mounted them on the first version of a manifold constructed from heavy duty steel pipe fittings.

First attempt

All seemed good at the time but a number of factors began to come to light that meant some changes had to be made.

1. I wasn't sure that the metal of the threaded nipples connecting the steel fittings was strong enough and may have been made from 'Blue band' rather than 'Red band' grade pipe. (Red band pipe has a thicker wall and is rated suitably for the Sentinel boiler's wet steam conditions. Blue band is not good enough).
   I replaced the connecting nipples with heavy duty hex nipples which are much stronger.
   
   
2. I was concerned that when I removed and refitted the safety valves for the boiler's next and any subsequent hydraulic tests, the thread would not make as tight a joint as the first time. They would also need to be removed to fit the boiler top cover.
   I inserted a 3000 psi rated union and mating nipple between the manifold and each safety valve body. The union is designed to be undone and also enables the safety valve to be correctly orientated so its exhaust pipe would align with its hole in the cab roof when refitted.
   This does make the assembly taller but practical!
   
   
3. I had assumed that I could obtain a steam supply for the vacuum brakes, the whistle and the pressure gauge from the four-way manifold used to feed the superheater. However, with all the other pipework in place, it was too inaccessible particularly to reach an isolating valve in that location.
   I thus decided that the safety valve manifold would have to include the steam supplies for the vacuum, whistle and pressure gauge.
   
   
4. At least one of the safety valve outlet pipes would have to pass through cab roof support girders. Not good!

Here's the result. Hex nipples hold it all together. The 3000 psi unions sit below the safety valve housings. The two 'L' shaped fittings are now 'T' shaped so the extra outlets can be taken from each of the new 'arms'. The vacuum supply is downwards from the left 'T' and the whistle and gauge supply horizontally from the right 'T' to an isolating valve.

The exhaust outlets now straddle the roof support girder!

Not cricket wickets!

There's more to do to prevent the pipes rattling in the cab roof holes and to ensure it all lines up if taken apart and reassembled.

In-Cab Boiler Feed Pump Drain Cocks

Having fitted Sentinel 7109's cab boiler feed pump some time ago, there was still some pipework to be completed. I'd constructed the feed from the water tank and the steam exhaust but there was more left to do (and still is!). This article deals with the drain cocks.

There are four drain cocks, one at each end of each of the twin steam cylinders, as in the photo on the right. However, in their original form, they were a mess waiting to happen as they would spew oil and water out on to the cab's ledge.

I decided that they needed drain pipes so that the outflow could end up somewhere more sensible.

3/16" Copper pipe is readily available for automotive brake systems. In preparation, I brazed compatible fittings on to the drain cocks as shown.

The Copper pipe is easy to bend by hand and the final result looks quite elegant.

The four pipes are taken through holes in the ledge and secured to the steam exhaust pipe with tie-wraps. (Let's hope they stand the heat!).

Finally the outlets are strapped to and just above the steam exhaust outlet. There is a thread on the end in case the exhaust needs to be extended later.

Full Vacuum Ahead!

Strictly this should be Vacuum Braking (14) Implementation (8), however, I needed a more vague heading!

Two new items have appeared on top of Sentinel 7109's cab roof: to the left is Nigel's coffin and to the right is a rather fetching and elegant periscope (respectfully looking away from the coffin!).

A Rail-hearse in the making?

The periscope, in a truncated form, will double as the vacuum ejector's exhaust outlet.

Up Periscope!

And finally, the boiler now has a leg to stand on. In fact, it's the beginnings of the blow-down valve pipework. I'd been checking out the four boiler washout plug holes around the base; one is used for blowing down the accumulating sedimentary detritus.

Caption competition?

The 'leg' showing will be red-band steel pipe to withstand the boiler pressure.

Meanwhile, in Steam Railway magazine (issue 441), there is an article about Sentinel 7109 in its 'In the Works' series. Any content in common with my blog articles is entirely coincidental, of course!

Vacuum Braking (12) Implementation (6)

My previous article on the braking pipework finished with a view of the beginnings of work in the cab. To say this involved some unsightly contortionist-like activities is an understatement because the space in which to fit this pipework is bijou to put it mildly. After a day of this, I need a day away to recover!

It also doesn't make it easy to take good photos. I hope the gist is clear from the following ones.

The first is the driver's eye view looking forward.

Avoiding the window and other pipework

I had originally planned to have the train brake handle below the cab's opening on the right. However, there are other bits and pieces reserving space on the side-panel such as the lever for remotely operating the exhaust condensate valve. It would also have meant the pipework passing under the shelf supporting the boiler feed pump where there are other pipes to be installed.

So I concluded that the best route for the pipe was around the top of the circular window aperture with the brake lever much higher up. Top right in the photo are the yellow-coloured silencer/air filter where air is let in to apply the brakes. Then there is the blue-handled brake valve lever itself with the vacuum relief valve just beyond it pointing up at an angle. There is a connection for the vacuum gauge right at the front.

It was not an easy job fitting the pipe around the window particularly the elbow at the top left. The pipes won't bend or give so they have to be exactly the right dimensions to go together! (I got it right on about the third attempt!).

The next photo is looking down to where the vacuum pipe passes through the cab floor (see the last three photos of this link).

Connections to the train pipe,check valve and Ejector

I've put a right angle in between the check valve and the ejector to shorten the length of the steam feed pipe. Hopefully this will reduce the length and weight of suspended pipework.

Ejector's steam feed

The ejector's steam feed is taken from below the left hand safety valve manifold branch (left foreground). It passes through the blue pressure reducing valve to the ejector via a cross (+) fitting which will allow for connecting a condensate drain valve and an ejector-feed pressure gauge. (The pressure reducing valve needs to be set to feed the ejector at its optimum pressure - 60 psi).

Next I have to assemble the safety valve manifold with steam seal and complete the ejector connections. Some extra Stauff clamps are also needed to support the vacuum pipe. Then there is the ejector exhaust pipe which will require a hole in the roof. Hmm, I'd better get that in the right place!

What's this?

Just by the driver's right foot, until now, there has always been a little pipe poking up through Sentinel 7109's cab floor. It's near the levers in the photo below.

Above the cab floor, bottom right hand corner

From below, it bends off towards the lower part of the boiler.

Below the cab floor, left of centre

It's lurked for a very long time, possibly since 7109 was first built in 1927. The trouble is, I've never been able to work out what it was used for and hence what it should be used for. So I've removed it. (If in doubt, chuck it out!).

In all its glory!

My only inkling is that it might have been part of the injector pipework fitted from new but removed after about a year of service. An earlier article described the saga of 7109's injector.

Well, I don't know if this is the case so I'm open to all (sensible) suggestions.

Keeping the Heat In (A Cover-Up!) (1)

From the beginning, Sentinel 7109's boiler had a top cover as shown in this old photo below:

Inside cab (a long time ago)
(Photographer unknown. If you claim to own this photo, please leave me a comment).

The cover was part of the miscellaneous collection of items belonging to but not fitted to 7109 on arrival at Midsomer Norton in 2004.

It has lain largely untouched for the last ten years but its turn has finally arrived. Looking at its original condition, it's not difficult to imagine why I'd ignored it until now.

Original condition showing the rusty edges

It doesn't look much better in the old photo at the top.

Close up of top/side join

The cover was made with top and side panels riveted to a curved angle iron support piece. As a guess, I would say that the riveting prevented any rust-proofing from getting between the angle iron and top or side panels. Thus continued exposure to condensation and wet caused rust to form and squeeze apart the joints. The result was a 'corrugated' appearance and many sharp edges. I could not see how this could be simply 'tarted up' without complete disassembly.

No better from the inside

I ground off all the 150 or so rivets for the various joints and punched them out. (The idea of removing 150 rivets was the main reason why I had kept well away from this task before! I even had to replace my long-serving angle grinder after it started to issue metal gear fragments and smell of hot plastic!). Eventually I was then able to practise my panel beating technique to flatten the areas to be re-joined.

Half top cover after deconstruction

The temporary joins look a lot worse than they really are. They will be screwed together with dome-head screws which bear a resemblance to rounded rivet heads.

Close up, better than it was

Now, after a coat of red oxide paint, one of the top covers is starting to look presentable.

After a coat of red oxide primer

Potentially, the cover could get very hot as it sits on top of the firebox and superheater which at times can glow red with heat. Much of the space will need to be filled with ceramic wool wadding to keep the heat in.

Also worth noting is some detail in the old photo at the top of the article. The superheater tubes coming out from the top of the boiler to the regulator and stop valve assembly are lagged. I think we had better do that too (could be a little hot to the touch otherwise!).