An “Austin 7” (not the car!)

[don9f]

Hi, now that the 3F is finished and the 9F overhaul nearly so, I’ve been wondering for a few weeks, what to do next? I’ve got all the castings and some laser cut parts for a Galloways Non Dead Centre Engine, but don’t feel it’s what I want to tackle at the moment, I want another locomotive project!
So.....I’ve taken the plunge and acquired the “rolling chassis” of an LMS Fowler 7F 0-8-0 engine. They were nicknamed “Austin 7s” for some reason to do with the car of that name being made at the time. There’s no boiler or tender etc. so there’s enough to keep me busy for quite a while. I have made contact with a chap who offers a design for a 5” gauge LNWR Super D 0-8-0 and we are hopeful that his boiler will fit. The tender was a Fowler 3500 gallon type, like that paired with a Horwich Crab, a Don Young design, so that’s easily available.
There are no members of this once 175 strong class of early LMS freight workhorses preserved and probably not much written about them....they were all scrapped by 1962, but there are quite a few photos online to go on like this one. I think they were quite powerful engines, but a major factor in their early demise was their poor axlebox performance....a legacy of old fashioned thinking during their design in the late 1920’s.

Anyway onto the model....I think it’s probably quite old but don’t currently know anything at all of its history etc. It seems to be quite well made and incorporates some intricate and novel features, especially with its “Joy” valvegear, something until a few days ago, I knew nothing about! This aspect itself is slightly odd, because the real ones had inside Walschearts gear, but I like a challenge and intend to do a complete strip down, remove all the old paint and check everything goes back together ok. There are a lot of round headed screws that I’ve already discovered are not very tight and these will have to go and be replaced by hex ones, suitably locked in place where necessary. Joy gear with all its links and pins, reminds me of helicopter rotor head linkages and the need for Loctite!

Enough rambling, here are some photos and relevant observations so far, starting with the gunmetal cylinder block with slide valves on top. Note the proliferation of oil points, wicks, feed pipes etc. to all the valvegear pins and so on:-



These engines had a larger spacing between the 1st & 2nd axles than the others:-





I was keen to figure out how the slide valves worked, porting etc. so the first thing I did was take the top of the valvechest off, for a look inside:-



Can’t say I’ve seen anything quite like this before:-



Moving on to wheels and rods etc. the front three sets of crankpins have some sort of self-aligning bearings and there is a bit too much side play in the 1st, 3rd & 4th axles for my liking, but maybe it was built to run on sharply curved track? We may never know!



It has “conventional” axlebox springing....note how the 1st axle has a stronger nested spring arrangement and also you can see the underneath of some of the Joy valvegear, plus the beautifully made big ends:-



The final photo today shows part of the most complex cylinder drains operating linkage I’ve ever seen, which links it’s five valves together, also note the worm/wheel gear for adjusting the main piston rod glands, which is obviously intended to be done from under the boiler, using a small square socket!



Hope that’s been of interest....

Cheers Don

[JonL]

Very interesting indeed!

[coniston]

I'm glad someone bought that one Don, I looked at it several times but I have just too many other projects. I'll look with interest how you get on with it as you uncover more of its interesting build.

Chris D

[mbrown]

Those worm and wheel gland adjusters are a fascinating concept for any inside cylinders loco. And that take on balanced slide valves is most interesting. Someone with real engineering imagination was responsible for this. I wonder if it ever got a boiler etc which was later lost, or if this is where the builder stopped.

I have to say the Joy valve gear is disappointing although obviously well made. However beautifully you complete it to look as close to prototype as possible, it will never be quite correct.... but it is a great project that will look great "on shed" with the 9F and the Jinty!

Malcolm

[don9f]

Thanks to all for your interest, apparently it’s previous owner (not its builder) had a brand new commercially made “Netta” boiler for it that allegedly fitted, but sold that separately.
Netta has a round topped firebox whereas this 7F should have a Belpaire type.....the model LNWR 0-8-0 boiler I referred to earlier is available as either, some of the real engines having both types during their lifetimes, hence the option. I have sent for the drawing of this LNWR Belpaire one to check the fit, I’m told it’s designed for 4 1/8” frame spacing, which this 7F is, the question being whether the 3rd & 4th pairs of hornguides need any alteration to clear the bottom of the firebox when the boiler is at its correct height etc.

Cheers Don

[stevep]

Those balanced slide valves are interesting, not least because they appear to be in one piece - unless there is something that can't be seen from the photograph.

If so, that means they have to be the exact size to touch both the port face of the cylinder, and the angled (exhaust) face on the cover.

I would be interested to see the underside of the valves.

[ettingtonliam]

In the first volume of his autobiography, E A Langridge devotes several pages to the design of the 7F, which he was involved with, being responsible for the valve gear. He was apparently given a pretty free hand with this, apart from the instruction to do away with the G2/Super D's Joy valve gear, so its curious that someone has set out to build a 7F with Joy valve gear!

Langridge says that the general sizes of the G2 boiler was used, though they did alter the tube arrangement, so there is a good chance a G2 boiler will fit your chassis.

Did the original 7F have piston valves?

Yes, those axlebox bearings gave trouble, predictably, because the loadings were much the same as those on the 4F, and the thought at the time was that the 4F axleboxes were satisfactory, which, with hindsight we now know they were not! Langridge says they were sufficient for MR days, but not equal to the rough and tumble of LMS handling.
175 were built at Crewe between 1929 and 1932, withdrawals began in 1949, with only 53 remaining at the end of 1951, the last going, as you said, in January 1962.

[uuu]

Presumably the slide valves, being wedge shaped, are held on their seats by the pressure in the steam chest, without the need for sliding internals. This could be a genius move!

Wilf

[don9f]

Hi, I’ve not had chance to do any more to the 7F today but thanks once again to everyone showing interest and adding to the story! Yes the real engines had piston valves and if you zoom in a bit, this photo shows an engine with the front valvechest covers off.
Each “light” coloured slide valve (could be white metal) is moved for & aft within a frame that is driven by the valve rod. There is just about zero clearance within the frames for & aft, but about 80 thou side to side and bronze springs bias them towards the centre-line, thus keeping them in contact with the exhaust ports, once the cover is in place.....it must have involved some very careful machining to achieve a good fit!
When the opportunity arises, I’ll take some close-ups of these parts.

It did cross my mind (probably ludicrously!) that the Joy valvegear could all be removed and replaced by Walschearts, but I don’t think that’s going to happen....I’ll keep it as a bit of a hybrid!

Cheers   Don

[Donald G]

Hi, I am about 80% through making the Galloways non dead centre engine, It is a bigger challenge than I originally thought, the drawings are not that clear in some places. Making the various parts has not been too difficult, but the thing I am strugging with is to get the piston rod crosshead guides positioned exactly right. They are really critical, I have left cylinder sorted, the right is just binding a bit, odd because it will work pretty well one way rotation, but go the other way it jams. Now frustrated as on the 1st June I had an ECG, and on the 11June a pacemaker fitted, so banned from workshop for a few weeks.
I do think watching the motion of the Galloway engine is very interesting.
As and when you decide to make it, I am happy to give any help I can
Donald

[stevep]

Jun 11, 2020 17:53:24 GMT don9f said:

SNIP

Each “light” coloured slide valve (could be white metal) is moved for & aft within a frame that is driven by the valve rod. There is just about zero clearance within the frames for & aft, but about 80 thou side to side and bronze springs bias them towards the centre-line, thus keeping them in contact with the exhaust ports, once the cover is in place.....it must have involved some very careful machining to achieve a good fit!
SNIP

Cheers   Don

That's really an ingenious way of ensuring the valve touches both the steam and exhaust ports at the same time.

I am always surprised that when balanced slide valves are used, they are not made with inside admission, so the valve chest, and the valve rod glands, are only subjected to exhaust pressure. With the layout of this particular engine, that would probably have been difficult.

[don9f]

Hi, before carrying on with the strip down of the 7F, I replaced the valvechest cover, made an adapter so the airline could be connected and rigged up a means of temporarily locking the reverser in position, so I could have a bit of a play. Obviously I had no idea what sealing of cylinder covers, or packing of glands etc. had been done but I had done some rudimentary checks that showed the valve events were “somewhere in the ball park”.

I have been reading up on Joy valvegear and both with knowledge gained, plus my own observations, it is evident that the absolute position of the fulcrum of the “curved link” with this type of valvegear is critical. To this end, the designer of this model made provision for vertical adjustment....no doubt to be carried out once the axleboxes are set at their correct, working height (I have read that this was also full size practice in the Works). Once properly set up, the bearings can be locked or dowelled in position....this hasn’t been done yet.

Problem is, I don’t know what the correct axlebox height is meant to be, so I’ll just set it at what I think looks correct. For now, spacers under the axleboxes are 0BA nuts!

Here is a short video of it running, after which I started taking it to bits and learning more of its hidden secrets!

All the motion pins have oilways drilled through them, lining up with the various oil cups etc. They are secured into their correct positions with grubscrews (none of these were locked in place yet). The builder must have spent countless hours making these parts alone.....
Dismantling the big ends revealed further spherical bearings which hadn’t been evident before. These two photos show the general arrangement of these:-





When I first looked at this engine, I was intrigued as to how the connecting rods and crossheads had been made, they really looked like miniature forgings. Now I know....they are aluminium castings! I’m not sure what to make of this, but they are quite big and beefy and the little ends are properly bushed for the pins, so hopefully they’ll be ok.

It wasn’t very long before I figured out how to remove the cylinder block from the frames, this being necessary for removal of cylinder covers, checking things over, packing of glands etc.



I’ve so far got one side pulled apart and something else I wasn’t expecting, the piston is aluminium too, with two rings of soft packing....will wait for any comments and will take more photos for the next update.

Cheers Don

[ettingtonliam]

in your video, there is brief side shot showing a linkage between the frames moving up and down and nearly touching the floor. What is that?

The work the original builder put in is phenomenal - those worm drive gland adjusters for example, and the self aligning bearings. I know from experience, having just done Locomotion's self aligning rod bearings, that there is far more work in getting a nice fit in a spherical joint than there is in a plain reamed pin/bush joint.

As for the aluminium piston, it wouldn't be my first choice, but if there is enough clearance cold, I don't see why not.

[don9f]

I’ve read arguments both for and against aluminium pistons, but I’ve never really thought about that before....the overriding factor against, being possible long term corrosion. As it’s easy to do, I think I’ll replace them with gunmetal and I already have a suitable chunk to hand.

The links you referred to are shown in this drawing, named the “anchor link” and the “jack link”. They are part of the linkage moving the die blocks in the curved guide, motion derived from the movement of the connecting rod. They do dangle down a bit below the frames, albeit staying above rail height.



Cheers Don

[don9f]

Hello, over the last few days I’ve been stripping down the engine, removing wheelsets, valvegear and finished up with the frames in bits. Then started the unenviable job of stripping all the old paint off everything, using a combination of paint stripper, cellulose thinners, a blasting cabinet and just plain scraping....but not necessarily in that order! The wheels were a nightmare and three days work went into getting them anything like ready to start again. One discovery during this exercise was that the wheels have steel tyres (presumably shrunk on) fitted to the cast iron rims.

The existing paintwork on it all was terrible and just had to come off, it had probably been on for years and some of it was cracked etc. but other areas took some shifting!  I’ve started to spray bits with primer, so at least it’s all starting to look better:-



As a diversion during all this, I have been making new screws to secure the cylinder block, motion plate and stretcher. The builder chose to use countersunk screws for these items and I identified the threads as 5/32” x 32 (BSW). I ordered a split die from Tracy Tools which arrived promptly and I’ve chosen to make my own countersunk but hex headed screws. Because some of the countersinks were “generous”, I’ve had to make those for the cylinder block from 5/16” hex steel, so as to just about conceal the holes, but those for the other two items can be made from 1/4” hex. One of the cylinder screw holes each side is very close to where a brake hanger bracket will fit, so they may have to remain as plain countersunk screws....we’ll see:-



This is as far as I’ve got with the screws, the heads still need finishing on this first batch and also shown are some commercial 3/16” x 24 BSW screws for future use with the axlebox horn stays:-



One last item for today....somebody in the past (probably not it’s builder) has had pliers on one of the piston rods and marred it up near the end that screws into the crosshead. I’m going to make a new one and this thread is 3/8” BSF, which obviously needs to be screwcut:-



Cheers for now    Don

[timb]

Looks like you have your hands full there Don. Was there any information with this - drawings etc or are you going to have to make it up as you go along?

Tim

[don9f]

Hi Tim, no information at all, other than that it was acquired by the Steam Workshop from someone down near the Romney Hythe & Dymchurch area, but who was not the builder !
Since the original post, I have satisfied myself that the boiler for “Wessie”, a 5” gauge LNWR 0-8-0 Super D engine will fit ok.....it is available as either a round topped, or Belpaire type firebox, so I have ordered a boiler kit from one of the suppliers.
I have also ordered some laser cut parts from MEL so I can make a start before long on the Fowler 3500 gallon tender.
To finish the engine, I shall probably work from photos, there are plenty online, plus reference to engines like the S&D 7F and LMS 4F classes, as I imagine there are many similarities in the cab etc. Its quite a simple design really, using what can be recognised from photos as “standard” Midland parts like brakegear etc.

Cheers Don

[mbrown]

You will probably have to change the position of some bushes etc on the Wessie boiler to accommodate the Midland-style cab fittings of the Austin 7!

Twin water gauges, slightly different combined injector steam and clack valves, no manifold on top of the firebox.... Maybe Don Young's ES Cox (Crab) backhead could be a guide?

You are making cracking progress and I love the hex head countersunk screws!

Malcolm

[don9f]

Jun 22, 2020 19:39:26 GMT mbrown said:

You will probably have to change the position of some bushes etc on the Wessie boiler to accommodate the Midland-style cab fittings of the Austin 7!

Twin water gauges, slightly different combined injector steam and clack valves, no manifold on top of the firebox.... Maybe Don Young's ES Cox (Crab) backhead could be a guide?

You are making cracking progress and I love the hex head countersunk screws!

Malcolm

Hi Malcolm....have thought about that a bit but not sure yet. This will never be a true scale engine, but yes, the backhead needs to look better than the 3F I’ve just finished. That’s pure Martin Evans and looks very old fashioned!

Don

[don9f]

Well I’d hoped to have more to show, but I’ve been bogged down removing old paint and cleaning things up ready for new primer etc. It’s taking ages....
I had honed the cylinder bores and satisfied myself that they were parallel (albeit a couple of thou different dias.) and measured around 1 27/32”, which are quite large and actually more than the scale 19 1/2” of the full size. I then made the new gunmetal pistons, electing to stay with traditional graphited square packing, as I already had some and made a new LH piston rod, because of the unsightly plier marks on the original:-



This next photo gives a closer look at the novel piston rod gland adjusting mechanism....either by use of a small square socket from above, or a screwdriver from below! These glands have been stripped down, cleaned and repacked with new graphited yarn. At the moment they have taken 6 turns and when nipped up, allow just a little clearance before the crosshead nuts contact them....I fully expect them to need taking up more when first steamed:-



The old red paint has since been removed from the cast aluminium crossheads (unusual?) and I’ll probably paint them black, along with the con rods, which are also cast aluminium. Apart from the curved guides, the other parts of the Joy Valvegear are steel, so I’ve got rid of the paint off them and will clean them up and leave them bright....don’t want red valvegear!

Sorry but they’re the only two photos I’ve taken recently but hopefully will have more to show soon.

Cheers Don