Thursday, 11 September 2014

Exhausting Pipes (2)

After some time in the making, the machined new chimney bases have arrived from Mendip Steam Restoration Ltd. It's worth a look back at an earlier article for where these fit atop the boiler.
New Chimney bases, Blast Nozzles & Exhaust Pipes
The photo above shows clearly how the exhaust steam flow divides into two to feed the pairs of blast nozzles.
Four Blast Nozzles showing blower rings
The short pipes showing against the orange pipes are the inlets for the blowers. More details are in this earlier article. Also try the label 'Chimneys' for all the relevant details on the subject.

The main difference between the old and new castings is the weight and hence strength. I used to be able to lift the old ones with difficulty; the new ones required help from a neighbour to get them out of my car! They are simply massive in construction and should last a very long time.

The trouble is that they will be very difficult to fit in place because of the weight! They also need the long chimney tubes to be fitted. Interesting times ahead!

Wednesday, 23 July 2014

In Search of the lost Nutty

'Nutty' is one of a peculiar breed of specialised locomotives that Sentinel made in the 1920s for brickworks use. Their prime requirement was to be very squat in height; very, very squat (5'2" in fact)!
Nutty lookalike - Works number 7243 built in 1928
(Photo from Sentinel Drivers' Club collection)
Built as works number 7701 in 1929 to a 2' 11" gauge, Nutty was one of about five constructed using steam waggon components.

In order to reduce the height as much as possible, the engine was mounted horizontally and the boiler very near to the ground. It also made driving a remarkably intimate experience!
No room for foot-plate passengers!
(Photo from SDC collection)
Neither of the above photos are actually Nutty; however, the next one certainly is.
Nutty in August 1971 at the Welshpool & Llanfair Light Railway
(Photo SDC collection)
The inner workings are clearly visible if you click to enlarge the picture.

I became aware of Nutty through conversations with curators of the Narrow Gauge Railway Museum in Tywyn, Gwynedd, at the terminus of the Talyllyn Railway (where I can be found volunteering on occasions). Nutty is actually owned by the NGRM but it never seems to be found anywhere near the museum!

Although originally built to a gauge of 2'11", it was re-gauged to 2'6" some years ago and it ran on the Welshpool and Llanfair Light Railway for a while. Since that time, I do not know exactly where it has been but I'm led to believe it has spent time at Railworld in Peterborough. In 2012, it made its way to the Leyton Buzzard Railway where it is on display at the Stonehenge Works station.

I visited the LBR on Wednesday 16th July 2014 and was made very welcome indeed. I wanted to poke my digital camera into Nutty's various nooks and crannies to assess its general state. I now have around 170 photos, not all are included here!
Nutty under cover at Stonehenge Works
Yes, it is chain-driven!
Side-on view
Cab internals showing the boiler
'Under the bonnet' view showing the engine beneath the water tank
Engine, water tank and boiler feed pump
Bijou accommodation for the driver!
There are clearly a number of components missing and regrettably I omitted to enquire if they existed. However, it was a good day out and many queries answered as to the construction of this strange locomotive.

Now who volunteers to restore Nutty, reduce the gauge by another 3" and run it on the Talyllyn railway?


See my Reference Material page for information sources.

Sunday, 22 June 2014

Nut & Bolt - Big Time! (2)

A few months ago, I described the manufacture of a new nut and bolt to operate Sentinel 7109's handbrake. Today I fitted it into place.
Linkage from nut to crank(1)
Linkage from nut to crank(2)
Some large split pins are still needed to complete the job. The largest I had are 1/4" diameter. 3/8" are needed. These things are big!
Optimism!
The brakes will have to be adjusted after the drive chains have been fitted but they do at least operate from the handle. The roller bearing under the handle seems to work satisfactorily.

Sunday, 8 June 2014

New Trousers in the Making!

A couple of years ago, I held a Wrong Trousers Appeal. I have to admit that there wasn't a huge response to the appeal but there has been considerable progress since.

The problem facing Sentinel 7109's chimneys was that the original cast base units were well past their best and that to use them would have only led to a long outage soon after becoming steam-worthy again.

A pattern had to be made to make the mould for the castings. It was made in four parts (with possibly a fifth but I've never been able to figure out where it could fit!).
Front (1) Outside Profile
Front (2) Inside Profile
Rear (3) Outside Profile
Rear (4) Inside Profile
Sentinel, possibly due to their former ship-board equipment product range, used the term 'Funnel' rather than 'Chimney.

Six castings were eventually requested: a prototype for Sentinel 6515 'Isebrook' at Quainton Road; one each for the Sentinels at the Middleton Railway, Elsecar Heritage Railway and the Bo'Ness and Kinneil Railway and finally two for 7109.

This is the prototype used to check that the pattern was correct.
Prototype casting before machining
The new castings have an additional feature to allow extra exhaust steam to be directed up the chimneys. The feature was requested for Isebrook so that exhaust steam from the vacuum brake ejector could be used to draw the fire. The feature is not expected to be used with 7109 but will be left accessible just in case.
Prototype after machining
I took one of the original chimney units to Richard Nixon to compare the old and new. From the pictures below, it's quite obvious how much extra metal and hence strength is built into the new chimney base.
New and old comparison (1)
New and old comparison (2)
Thus I am happy that it was the right decision to go for the new casting option.

7109's castings arrived in the middle of April 2014.
Nice new pair
They are very substantial and will undoubted last a long, long time. They have been taken to Mendip Steam Restorations Ltd for machining and fabrication into complete dual chimney units.

Again, all the pipework and blast nozzles have to be carefully made to fit together. Hence, the whole job has been passed to MSR as it is beyond the capabilities of equipment available at Midsomer Norton.

Prototype and pattern pictures were kindly supplied by Richard Nixon.

Wednesday, 4 June 2014

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.


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