Cylinder Oil Reaches Regulator

On a Sentinel locomotive such as 7109, Steam or Cylinder oil is injected into the superheated steam supply as a means of lubricating the engines' cylinders.

As the steam supply is at boiler pressure, the oil needs to be injected under pressure and that pressure is generated by a mechanical lubricator. I've described much of its configuration in an earlier article.

Part of the pipe leading from the Mechanical Lubricator to the regulator was missing from 7109 and I decided that it would be simplest to replace it and fill the gap using PTFE lined flexible high-pressure hosing with integral fittings.

Initial efforts failed to pump any oil into the new pipe section so I had a think and came up with a Heath Robinson construction to cure the problem. It actually follows from an idea described in the Delvac Mechanical Lubricator's manual (courtesy of the National Library of Australia). The intention is to use a lever to operate an individual pump as shown below.

Unsophisticated!

It operates like this (Also on YouTube):

The end result is shown below:

Oil Dribbles from the bleed valve outlet

The braided flexible hose is shown fixed below the bleed, check and oil regulation valve assembly.

Main Steam Pipe Release Valve Outlet

When Sentinel 7109's regulator is closed, it blocks the steam supply pipe to the engines. With a four to one reduction ratio between the engine speed and the axle speed, this will provide what's called 'Engine Braking' (Big time!).

To prevent things stopping too abruptly, a release valve is provided that opens the main steam pipe to atmosphere when the regulator is moved back to the right beyond the closed position.

Release Valve (at the bottom)

On the regulator handle is a 'lump' containing a spring and a ball. On the housing is a hole which marks the regulator closed position. When the regulator is closed, the ball notches into the hole to indicate closure. The regulator handle then has to be pulled back beyond the closed position to open the release valve.

I had to shape a 1/2" pipe to fit around the main steam pipe and through the original hole in the footplate.

There were two challenges:
(1) Having used a union at the top end of the pipe, I found the nut used to tighten the union fouled the nuts holding the main steam pipe end fitting in place. I thus had to add a short extension to drop the union out of the way.

Elegantly shaped Release Valve Outlet Pipe

(2) The hole in the footplate was under the boiler cladding such that the lower pipe end would not fit through the hole. I thus had to cut the pipe, add a coupling and feed the lower end of the pipe up from underneath. I cut a tapered thread on the top section of pipe and screwed it into the coupling very tightly. I cut a parallel thread on the pipe from below such that it would be the section that came out of the coupling if it ever needed to be removed in future. (The coupling itself will not fit through the hole).

Lower section of pipe below the footplate

'The End'

I've put a round-edged coupling on the end of the pipe to prevent me from gouging a lump out of my head whilst passing underneath!

Pipe Reality Come True

My previous main steam pipe article was at the stage of it being persuaded into a shape that should fit. In practice, it wasn't that easy.

The first challenge was that, being such an awkward shape, it would have been easy for Sentinel to make it fit with 7109, the pipe and all tooling collocated in the factory. With the pipe being made five miles from 7109, it could only be made to approximately the right shape using a jig made using the old pipe geometry. Mendip Steam's Andy Melrose eventually gave in that some heat was going to be needed in the cab to make it fit. Thus 7109 had her first fire lit since 1968!

First fire in 46 years

Not much steam was created but it did seemingly allow the pipe to ease into place, or so we thought.

Everything was fine until the second challenge. The nice new end pieces were made to drawing size but that did not mean to say that the original mating joints were made that way.

Nice new end fitting exactly to drawing size

The mating end under the water tank had at one time been repaired and the hole into which the new pipe had to fit was not actually round! The two parts would not fit together.

There was nothing for it but to grovel about underneath with a miniature grinder (it's not made for a human to squeeze under the water tank) and make the mating hole bigger, not a lot of fun!

The underneath end finally in place

The fitting in detail...

...fed by a pipe around the firebox...

...fed from up here in the cab...

...from the regulator all the way up here!

So the pipe is at last in place. The white insulation is made from glass fibre ladder tape wound over partly dry, tacky red oxide paint to keep it in place. Finally the ends and a centre join are secured in place with galvanised wire.

Glass fibre ladder tape

The pipe joints are sealed using 3mm thick annealed copper washers, made from copper sheet, with lashings of SteamSeal. The copper washers were made by cutting the outer perimeter with a hole saw and the inner hole with a screw tightened hole punch. Glad I wasn't in a hurry for these, it took ages.

Boiler Fittings (6)

At the end of my last article on the boiler fittings, I was left having to think a while as to how to make the superheater actually fit its fittings.

I realised that the boiler top-plate and four superheater rings were all tightly fixed together by their mountings. As a result, I was having to cajole each ring against the wishes of the rest of the rings.

By loosening the fixings, each ring could be adjusted independently of the others and of the boiler top-plate leaving much more slack to play with.

So after some careful height adjustment with the sky-hook, here's the result.

Regulator and superheater connection (1)

Regulator and superheater connection (2)

Not obvious in these photos is the use of 2mm thick annealed copper washers to seal the mating faces of the superheater joints.

Steam feed manifold (1)

Steam feed manifold (2)

Steam feed manifold (3)

My apologies for the poorer quality of these photos, I forgot my usual Canon Powershot S95 and had to resort to a mobile phone!

If you are still wondering about the skyhook, click here!

Boiler (Not) Fittings (5)

Having fitted the steam feed manifold and regulator assembly to the boiler, the next job is to join them together using the 4-ring superheater.

I recall being hugely relieved when I was told in June 2011 that our superheater was new old stock and had never been used before. Brilliant, I thought; however, there is a down side to this in that it has also never been joined to a set of steam fittings before... Could this mean that it might not fit first time 'out of the box'?

Have a look at these:

Superheater not quite above the regulator assembly

Superheater not quite above the steam feed manifold

In fact, the superheater really does not align very well at all! I decided on Monday 4th March that it was time to put this aside and think about it for a while!

Not only do the fittings not line up but when they eventually are 'persuaded' into place, the boiler top plate will then not align with the boiler top itself!

In 1973, during my student apprenticeship in Newcastle, I spent 6 weeks in a fitting shop at C A Parsons & Co Ltd, the sadly long-gone Turbine-Generator manufacturer. I never thought I'd ever find that experience useful again - little did I know what I'd need in later life!

Boiler Fittings (4)

A before and after pair of photos of the regulator sub-assembly:

Is it new or does it just look new?

Or how about a nice authentic aged look?

Which do you prefer? Sometimes authenticity is not the best way!

Boiler Fittings (1)

Remember this item from a previous article?

Superheater feed manifold

What about this one? Possibly a more recognisable item depending on how well you've been following my 'blog exploits in the past.

Regulator Assembly in place (before restoration in December 2004)

The first is the four-way manifold used to feed the boiler's wet steam output to the four-ring superheater input; the second is the regulator assembly which receives the output from the superheater.

I showed the fitting of the superheater in a previous article confidently assuming that it could stay put from then on as in the photo below.

Superheater assembly neatly sitting in the top of the boiler

How naive!

What I hadn't spotted was that, with 2" studs sticking upwards from the manifold and regulator assembly, there was no way that these could be fitted on to the horizontal studs on the boiler without lifting the superheater about 3".

The only lifting gear at Midsomer Norton is a road-railer but it has not been available for some time. So ingenuity was going to be required.

Temporary Aerial convergent 'plate-way' in use!

I knew I could lay my hands on a jack and a lorry strap and that the superheater weighed about a quarter of a ton. After a few checks, I found my trolley jack was rated at 1.8 tons and the lorry strap at 3 tons so all was well within safe limits.

So it was a simple matter of putting the plate-way (point rods) in place to support the jack, tighten the straps and jack up the superheater. It worked like a dream!

Precise lifting ability

The jack is ideal for this as it can lift the superheater precisely to the right height and then lower it on to wooden beams for longer term support. Not wise to depend on the strap (particularly as it would get in the way of keeping out the rain!).

Interim resting place
Superheater rings showing below the top plate

So far, so good I thought until I tried to fit the manifold.

When the boiler was refurbished, all the studs were renewed. Of course, the new studs protrude precisely at right angles to the curved surface of the boiler - which means that they are not parallel! They are further apart at their outer ends than at the boiler surface and hence wouldn't mate with the holes in the manifold flange.

Five brand new studs for the manifold fixing
(there is a blanking plate fitted in the photo for a hydraulic test - I guess it had bigger holes!)

I've got a few options: bash it hard enough to make it fit (don't like that); grind the edges or ends of the studs or bend the studs so they are parallel (maybe); drill out the holes in the manifold flange (not keen on that). I'm still thinking about this!

More to come when the bits are in place.

Sentinel 7109's regulator and operating valve assembly

When Sentinel 7109 arrived at Midsomer Norton Station in December 2004, it was in a pretty rough and partly disassembled condition. The regulator assembly was covered in rust from a few decades of atmospheric exposure.

Regulator Assembly on arrival(1)

Regulator Assembly on arrival(2)

The regulator valve internals were unserviceable.

Original inside surface of regulator valve...

...with valve segment in place

The stop valve was unlikely to stop anything!

Stop valve pitted with rust...

...deeply pitted that is!

But in the right hands, things come back to life.

The refurbished regulator valve...

...and a stop valve which will stop something...

...and all the rest of the bits and pieces!

The whole regulator and operating valve assembly has been completely refurbished superbly by John Goold of J R Goold Vintage Steam Restorations Ltd in Camerton.

Refurbished valves