Blog- brightspark's Blog - 76010 Cylinders and Valve Gear

RSS Fetcher · October 12, 2014

Fitting Walshaerts valve gear has in the past filled me with dread. It was one of the reasons why I started with pre-group Midland where things like this are nicely hidden away. However here lies the tale of my attack (with help from Branchlines) on the Walschaerts valve gear.

Going back to 76009, this was my first attempt at this tricky valve gear but the Comet kit did give me the confidence to continue. That kit has some nice castings for the cylinders but I get the feeling that there is something not quite right there. Perhaps because they are generic for a number of kits and may be a little too large when viewed from the front? I have not measured them so can’t comment further.

(I do hope that Comet come back onto the market after the death of Geoff Brewin. At the current time there is uncertainty about this range of products. http://www.rmweb.co.uk/community/index.php?/topic/88317-comet-models/page-4)

The Branchlines kit is a set of etched parts for the cylinders and I must confess that I was bit anxious about this. But by taking each step methodically and checking at each stage that everything is square, true, de-burred and clean, then as I found, you don’t get any problems.

So in the interest of the build here is a semi completed cylinder minus the outer wrapper (top right) and the parts for the other side.

The outer wrapper is formed before soldering on to ends. It did this by bending it around file handles. One handy tip is to use a bit of card board between your fingers and the metal. Two reasons for this, the first is that the metal bends across a wider area and so is not only easier to bend but is less likely to bend unevenly or grease. The second reason is that is saves your fingers getting ripped to shreds.

Having completed the cylinders we now start to work on the motion gear. I followed the instructions that came in the kit but there are a couple of points that I fell could be described better.

1. The instructions advise cutting a slot for the Combination lever. You need to cut out the whole back of the valve guide casting (the little joining bit at the back so it looks like a U)

2. The instructions tell you to assemble the Radius Rod to the Combination Lever before fitting through the Expansion Link and Motion Bracket. You can’t do that as the hole through the Expansion Link is not wide enough to take the double thickness of the lifting link. Alternatively assemble the linkage through the arm and bracket then link it to the Combination Lever.

Here is a picture showing what you need to cut out.

And here is the valve assembly assembled.

To compare and for interest here is a picture of the actual gear from 76017 being restored at the Mid Hants Rly

That can be found here

http://www.watercressline.co.uk/archive/Images/News/Loco/941-8.jpg

and these of the expansion link and die blocks, showing their location and how it all fits together.

http://www.watercressline.co.uk/archive/News/Loco/View/741.html

Next is the assembly of the reverser gear box.

Here is a picture of the flat parts. Branchlines include with the kit a really nice little casting of the reversing gear box. The instructions offer a fold up box that can be used with the reverser or on its own. To be honest I couldn’t make much sense of this as the one hole required for the Weighshaft that passes through the frames to right hand side is in the wrong place. Nor is there a location for the casting on the frame. The other side seemed to be more straight-forward so I worked on that first to that see if I could decipher what the kit designers intention is and the Weigh shaft might give a good location for the gearbox.

I will recommend that you search through the Mid Hants Railway Blogs (Watercress line)as in the archives there are pictures of 76017 (and other locos) being stripped and restored. (It is taking them an age though as they started the restoration back in 2010!) These pictures come in handy when trying to visualise how the engine goes together and more importantly what goes on in the shadows as footplates etc have been removed.

With that in mind, this handy picture from early in 2011 shows the right hand side of the loco.

http://www.watercressline.co.uk/archive/News/Loco/View/397.html

You can see the bracket for the Weigh shaft in front of the guy in the green overalls and how far out it comes, i.e. right behind the lifting link. Also note that there is a horizontal part of the bracket. Following the logic of the rest of the kit, it isn’t explained at this point; the etched part has half etch lines and would indicate that the bracket should be shortened for EM/P4. But if you do that you remove the horizontal part next to the frame and the bracket will also be too short as it should sit just behind the lifting link. So I have fixed it into position without any shortening. The Weigh shaft also picks up onto the lifting link and here both Comet and Branchlines struggle with the geometry as both seem to have the lifting link just a little too far forward. This means that you either miss out the weighshaft or deform it slightly. I choose the latter.

With the Weighshaft soldered to the gearbox and located into the right hand bracket I can now get a better idea as to what happens on the left hand side of the frames. This simply involves lining up the two cylinder assemblies, the shaft from the gearbox to the cab (well the underside of the footplate and marking out the hole position.

Somewhere about here.

On the casting of the gearbox is a shaft with a step. I guessed that the step was the spacing for the narrower frames required for OO. And after soldering up found out that I was wrong.

This is the spacing for OO. However it is not a problem as I simply unsoldered the fixing, opened out the hole and reassembled.

A nice touch is that there is provision for a wire stay to hold the reverser shaft. This should of course also line up with the pips under the footplate.

With the reversing linkage lined up I can now check that the Walschaerts gear is going to work properly. Unfortunately there is a problem with the Combination Lever fouling the Crosshead. So using some of the nickel silver fret I have made up a dummy Valve Spindle, as this is not included in the kit (Understandable as it can't really be seen), and glued it in place so that it guides the combination lever out of harm’s way.

Finally there is a mounting bracket for the injectors. This wasn’t in the Comet kit so on 76009 the injectors and watercocks just hang in space. The photo above shows this bracket quite clearly lurking under the cab.

There is just one thing missing. In the middle of the cylinder casing there is an inspection cover. It looks to be about 12” diameter. The Comet kit includes an etch for this cover but Branchlines has omitted it. I made one up out of thin card by cutting around a screw head and then pressing out the bolts with a pin.

Here is a picture showing where it goes. (Again from the Mid Hants)

http://www.watercressline.co.uk/archive/News/Loco/View/579.html

With that in place, the chassis is now ready to go into paint.

While we wait for the paint-shop to gum everything up another oddity of this standard has come to light. It is the square box on top of the cylinder in that last photo. It is an inspection cover but none of the other standard classes seem to have them.

Until the next instalment.

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