Boiler Fittings (8)

Thursday 7th January 2016 saw Sentinel 7109's original boiler water gauge glasses being fitted finally as in the photo below.

Right hand gauge glasses

I last wrote about these in April 2013 when I'd obtained replacement glass protectors and checked that they would fit. Now the valves are in for good (hopefully).

Gauge Glass Valve arrangement similar to 7109's

Having remembered to insert the new 3/4" stainless steel balls into the lower valves to reduce the amount of steam escaping should the glass tube break, I proceeded to attach the component parts to the boiler. The upright steel tube is very straight and is used to ensure that top and bottom valves are aligned accurately when the glass tube is tightened in place.

Steel tube passing down through the upper valve to the lower one

It was not that difficult to achieve the alignment which is probably down to the 
curved surface of the valve faces matching the curvature of the boiler. I'm glad that new valves with flat faces did not have to be used!

Upper valve

Not so obvious from these photos is that each valve face is sealed to the boiler using a combination of graphite gasket with suitable lashings of Rocol Steamseal.

Lower valve showing close fit around the steel tube

I was then able to put the glass tubes in place and tighten them up. The word 'tighten' here is quite subjective. Sentinel used hexagonal graphite packings for this situation as below.

Hexagonal glass tube packings (photo from Heritage Steam Supplies' website)

They fit around the glass tube and are compressed to seal the tube. However, they should not be overtightened to prevent the glass being destroyed and they should align with the hexagonal spaces within the screw clamping mechanism. One of the glasses did not seal well so I may not have got this right and will have to recheck.

But how did I know that the seal was not so good...? That will have to wait for my next article (and I promise it will be worth the wait!).

Implementing 'A Little Arithmetic'

In a recent Sentinel 7109 article, I did some 'arithmetic' to enable a new boiler blow-down valve to be fitted. The result was this elongated heavy duty hex nipple pipe fitting made by Justin Goold.

Elongated Hex Nipple

The photo below shows that it has provided the solution required and is a good, strong fit to support the substantial high-spec blow-down valve.

The Valve is firmly screwed into the wash-out plug-hole

Another view shows valve handle in its closed position. An extension handle like those used to turn-off your household water supply in the street will be useful here.

The handle is reached from the off-side
preferably with a long reach extension

Down-stream of the valve, the pipe fittings are galvanised malleable iron as there is no longer the boiler pressure to withstand.

Not a good place to be when the valve is opened!

Another hole in the boiler plugged!

Important Note: The boiler has four washout plug holes at 90 degree intervals. For washout purposes, only the three actual plugs should be used. Only under extreme circumstances should this valve and its hex fitting be removed. The result would be that it will not be able to be tight and in the correct orientation after refitting due to wear on the threads when it was tightened up previously. Thus, it has to be a fit once and leave well alone item.

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.

Steam Brake Air Tested

In June 2012, I last wrote about Sentinel 7109's steam brake cylinder. Time passes and I've learnt that restoration is not a rapid activity!

The brake cylinder was reinstalled on Monday 7th December 2015 and here it is in place bolted to the left hand frame member to the rear of the boiler. (Bearing in mind that I can only just lift the cylinder on my own, getting it into place under here was not a straight forward exercise and required a selection of trolleys, levers, bits of railway sleeper and a lot of ingenuity to get it home!).

Brake Off

Spot the difference!

Brake On

To see it in action, here's another of my little video clips (Also on YouTube).

Sounds like heavy breathing!

The testing involved connecting a compressed air supply to the Driver's Brake Valve (DBV) inlet. Movement in the video was controlled using the DBV itself as would be normal practice with a steam supply.

DBV Top Left

The brakes still need to be adjusted but that can't happen until the front drive chains are in place and the axles located for the correct chain tension.

Checking back over the 'blog, I've not been able to find anything on the Driver's Brake Valve itself. I've had the photos since December 2012 but they slipped through the net.

The Driver's Brake Valve has an operating shaft and three connections to it - the steam supply inlet from the boiler; the outlet to the brake cylinder and a drain to atmosphere to release the pressure on the cylinder piston to let the brake off after application.

DBV connections

DBV Operating shaft

The operating shaft is extended across the rear of the cab to allow the brake to be operated from either side.

Dual Controls 1927 Style!

I took the following photo just after taking co-ownership of 7109 in 2010. A few bits & pieces had been removed and examined ('played with'). There was a long journey ahead!

DBV in October 2010

For completeness, here's the Sentinel factory drawing of the DBV. It is a general drawing showing that it could be operated from either end although 7109 did not use it that way.

Sentinel DBV Sectional Drawing

Other locos mounted the DBV in the centre rear of the boiler with handles either side.

DBV in Sentinel 9599 (William Mk1)

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!)...