Saturday, 25 April 2015

Vacuum Braking (11) Implementation (5)

Following on from Vacuum Braking (10), it really is true that the whole pipe structure can be dismantled and removed and here it is laid out on Midsomer Norton station's down platform.
Front to rear vacuum pipework
The next job was to replace it all beneath the footplate and frames, then to complete the Stauff clamp fixings and tighten it all up.

The fixings presented another opportunity for the sky drill under the water tank.
Suspended on rails between the rails
The holes were tapped for M6 mounting screws (or, in this case, twice over as the tap tool broke and had to be left buried deep in the water tank metal work. It's covered by the clamp now so nobody will ever know!).
Clamp and hidden holes
Forward-most mounting clamp
Earlier I'd had trouble aligning the hole through the cab floor with the pipework's 'T' junction below. Having started to tighten up the clamps, the situation was beginning to get worse. Previously I'd enlarged the hole to a figure '8' shape; now the hole still did not seem to be long enough but this time I'd run out of space in the cab due to the sanding gear cross-shaft.

My only option was to put a kink in the pipe to realign it.
Joyce's Kink!
Now things were starting to behave themselves and I was able to fix another Stauff clamp and bracket in place to support the pipework from above.
Clamp, bracket and sanding gear cross-shaft (red bar) near the cab front
Finally a quick mock-up of the ejector (aka. jet pump, 'little sucker'), non-return valve and 'T' for the brake operating handle - all connected to the completed pipework below (and Joyce's hidden kink!).
Ejector and non-return valve
Now I'll be able to spend more time in the cab instead of underneath, flat on my back. Having said that, there's a lot more space below. Lonnie Donegan summed it up a few years ago: "There's not mushroom inside"!

Tuesday, 14 April 2015

Vacuum Braking (10) Implementation (4)

In implementation (2), I'd started to plot the vacuum pipework route and had begun mounting it under the footplate. Now I've managed to join it up with the front end and broken up through the cab floor (I'm enjoying this, it's like extreme Meccano but different!).

The first set of photos are looking rearwards (and upwards).

The pipe comes forward around the RHS of the boiler and then dog-legs to get around the RHS rear wheel.
Continuing from the dog-leg with clamp in place
A 'T' provides the upward connection to the cab apparatus.
'T' Junction upwards to cab
(Note: the curtain is not for decoration; it is covering the inter-axle chain to keep me a bit cleaner while under here. I suppose it does add a little to the sense of homeliness in a working environment!).
Up through an interesting hole in the cab floor
After turning left behind the water tank, I had to be very accurate to enable the pipe to fit between the tank and the existing pipework.
Then stitching across to the LHS between the exhaust pipes and the water tank...
...down and round the tank bottom corner and towards the front...
Then once below the water tank bottom surface, the pipe can point forwards again.
...alongside the LHS exhaust pipe...
These photos are looking forwards (and upwards).
...towards the front...
...beneath the water tank and then above the front axle...
...finally dropping down to avoid the counter shaft and
diagonally across to the front vacuum connection
The front vacuum connection
These photos are looking backwards and upwards again.
Diagonal and level then up and over the axle
Up and over the front axle
When the joints have been tightened, the pipe will no longer foul the right hand chain sprocket.
To the rear of the water tank bottom then stitch between the pipes
Meanwhile, in the cab:
The vertical pipe will have the vacuum ejector connected along with the brake operating handle, vacuum gauge and vacuum relief valve.
Where the little sucker connects!
The pipe underneath still has to have its clamps fitted - another opportunity for the sky drill! I'll use fairly shallow holes into the water tank; I wouldn't like to add an extra drain hole!

A few points of note:
There are seven union joint fittings between the front and rear buffer beams. These enable the whole pipe structure to be dismantled and removed. Since I installed from rear to front, dismantling should be done from the front to the rear.

All the pipe's tapered male to parallel female thread connections have been sealed using Heldite. I find this superior by far to Teflon tape as it is easy to brush on and it fills all the gaps. It also does not set hard and allows the joints to be undone at a later date.

I'm not sure I like the diagonal pipe towards the front although it does not seem to be in the way of anything else.

Another day or two should see the underneath vacuum piping completed then the cab apparatus gets its turn. I'm starting to feel quite confident that the end is in sight!

Saturday, 11 April 2015

Vacuum Braking (9) Implementation (3)

In Vacuum Braking (8), I mentioned the Stauff clamps I was using for attaching the pipework beneath the footplate. What I didn't mention was the difficulty I was having drilling and tapping the mounting holes.

Drilling upwards through 1" steel plate with a hand-held electric drill is not easy whilst lying on your back. I have to admit that previously this had proved painful and was taking about half an hour per hole.

Bearing in mind, I might have to drill 30 or so holes this way, I felt it was time to think of a better way. For years, there have been stands to convert an electric drill into a pillar drill of sorts but they were designed for drilling downwards (easy!). However, if you play about a bit, it can be adapted for 'skyward' drilling.
Sky Drill
By throwing away the instructions, it's possible to assemble the components so that pulling down on the handle (to the right in the photo) pushes the drill upwards. The base needed to mounted on a board to take the pull on the handle without it all falling over.

And the result is below:
Another clamp attached
This particular clamp was above the brake linkage behind the rear axle. It is absolutely impossible to lie down under this part of the footplate and drill upwards in any other way (nor is it possible to find where to drill downwards from above the footplate either!).

Frankly, I'm really quite pleased with myself for this idea!

Friday, 10 April 2015

Chuff Proofing (2)

In Chuff Proofing (1), 7109's co-owner Nigel had completed the superheater outlet steady plates.

Now he has completed the inlet steady plates which were more awkward than the outlet plates due to their inaccessibility at the front of the cab and the arrangement of the pipes themselves.
Snug fit around the inlet pipes from this side
A small gap is left around the nearest pipe below which will have to be blocked with ceramic lagging for a better seal.
Air conditioned this side!
Another job completed!

Tuesday, 7 April 2015

Vacuum Braking (8) Implementation (2)

In Implementation (1), I showed some of the vacuum braking system pipework. Below is the fuller picture including the safety valves, manifold and feed to the vacuum system.

From the safety valve manifold (with the flange), there is an isolating valve, a blue pressure reducing valve, a 'cross' for feeding the ejector (jet pump), a condensate drain and pressure gauge and then the ejector itself and its up-standing, tall exhaust pipe.

Off to the right of the ejector is a Gun Metal Lift Check Valve, a 'T' to the train pipe, a 'T' for a vacuum gauge, a 'T' with the vacuum relief valve in place and finally the brake operating ball valve with a Sintered Bronze Pneumatic Air Muffler (silencer).
A bit more of the beginning!
The train pipe is a challenge in itself for reasons which will become apparent later.

Originally, I'd conceived the train pipe to be made from 2" nominal inside diameter pipe as used on 'big' locos. However, a discussion with Michael Patterson, who is restoring Sentinel 9366 at Quainton Road, made me appreciate that we will not be attempting to evacuate rapidly a train load of 14 Mk1 carriages. Instead we might have 2-4 carriages which will be a much less demanding task. Add to this that the ejector itself only has a 1" diameter suction pipe and it calls into question the need for 2" pipe. Add also that I have ready access to pipe threading tools that can handle up to 1.25" pipe and the case for 2" get even slimmer still.

I thus decided to use 1.25" galvanised pipe and malleable iron fittings for the vacuum system with adapters to the 2" standard fittings on other vehicles.

The basis for one such adapter is shown below. The classic steam loco's 'Swan Neck' is constructed as below. The 1.25" pipe is adapted to 1.5" fittings which can be turned down to make the correct diameter to fit the rubberised vacuum hose. A short length of support pipe may be needed to keep the pipe from slipping off (unlikely when a vacuum is present but safe if it did happen since it would break the train pipe and put the brakes on).
Swan Neck
On 7109, the rear one looks like this after turning down the 1.5" 45 degree fitting.
Rear Vacuum Pipe and Swan Neck
The vacuum pipe routing is not going to be easy but is made less challenging using the smaller pipe diameter. One possibility was to route the pipe under the RHS running board. However, this space also has to accommodate the sanding box operating mechanism, the extent of which is currently unknown. To wait for the sand boxes to be sorted would bring this activity to a halt so I decided to do it the hard way!

This is the plan:
The rear pipe has to tuck under the buffer beam and across it.
Inside the rear buffer beam
Then it will pass in front of the handbrake mechanism and round the large bracket...
Hand-brake mechanism
...and along the inside of the off-side loco frame.
Inside the frame below the footplate looking rearwards
The curved pipe in the above photo has been removed.

The pipe then has to come forward to where it will 'T' off upwards to the vacuum ejector suction port and brake operating lever.
Forwards through a restricted space
Then things gets tortuous. The pipe has to cross from the right to the left between the lagged exhaust pipes and the water tank...
Between the upward exhaust pipes and the rear of the water tank on the left.
... and along underneath the water tank to the left of the three insulated pipes.
Space to the left of the three insulated pipes
Finally it will cross beneath the engines and connect to the front vacuum pipe and its Swan Neck.

The first few steps are shown below.
First it tucks under the buffer beam via a right angle union connection to allow the Swan Neck to be aligned rearwards.
Tucking under the buffer beam
Then it crosses to the right under the footplate...
Under the footplate
...and to the front of the handbrake screw mechanism...
Avoiding the handbrake
...and round the bend via another right angled union to enable the next section to be attached from the front.
Right angled union
The pipe is held to the footplate above by Aluminium Stauff clamps which grip the pipe tightly and provide a strong mounting. M6 Allen-headed bolts of 70mm length are used to attach the clamps to a threaded hole. Flat and spring washers are also needed to spread the load and prevent the bolt shaking loose respectively.

The pipe advances forwards through he gap at the top of a supporting bracket.
Handy gap for a pipe
It needs a dog-leg to avoid the rear RHS wheel.
Section of plank supporting the pipe
Now it gets to the tortuous part but that's for another article as I haven't got there yet!
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