t*# 1 GAUGE

No. 1-1977 1% " Power at Echills Wood Railway, Stoneleigh. 'Colossus' and 'Zebedlia' by Roger Marsh of Hinckley.

A Publication of the 7HGauge Society

^ 7WGAUGE SOCIETY President C.R.H Simpson

Chairman Editor Secretary Treasurer W.R. Jones, Dr. J.B. Rogers, D. Walters N. Rainbow 295 Westbourne Grove, Porters Hill Farm, 16 Station Road Merry Hil l , Portway London, W.11. Nr. Droitwich, Kenilworth, Warks. Nr. Upton-St. Leonards, 01-727-7051 Worcs. Kenilworth 53244 Gloucestershire

Worcester 52397 Gloucester 66244

714 GAUGE NEWS

EDITORIAL

The publication of the first copy of 714" Gauge News marks a further milestone in the affairs of the Society. The Society is now aged 3 Vi and the 2(X)th member has just joined — we have lost a few through lapsed membership, but this happens in all Societies, and the Committee are looking into ways of ensuring continuity of membership by means of Bankers Orders, or other devices as mentioned by the Secretary in his notes

We have a good deal to be pleased about: the increasing interest in 7'/i" Gauge is in some measure due to our public image. We have set up a Register of Members and have initiated a Register of Locomotives, about which information is carried in this journal; a Register of Tracks is proposed. We have appointed a Trade Liaison Officer who is already able to offer some alloy rail at advantageous prices to members. The meetings and rallies have usually been well attended and the programme for each year becomes more stimulating. There is interchange of ideas, equipment, jigs and tools and patterns between members. Many members have had the opportunity of driving their locomotives on long, well-laid tracks when on Society visits. There have been other "perks", for example footplate trips on the R.H.D.R. and special Society visits to Great Cockrow, Hilton Valley and other lines. Nevertheless, there is no room for complacency. We require to build up the membership and interest in 714" Gauge. The Committee would welcome the efforts of all members in two respects in particular: firstly, that expenses should be kept down by members making sure that subscriptions are paid promptly — they are due NOW — and secondly, if you hear of any person in the 7W" field or generally interested, try to persuade him to join us.

The News replaces the old Newsletter (of which nos. 1-10 will surely be a collector's item in due course), and it is time to thank those who have subscribed to its success. The contributors are, of course, the people most responsible for this, and it would be be invidious to mention by name. An exception must be made in the case of our President, who has so entertainingly allowed us to benefit from his wit, wisdom and experience. Nigel Rainbow designed and produced our "Newsletter" headings, and neither the "Newsletter" nor the "News", to which he now bends his professional skills, would have been half so attractive without his efforts. Mrs. Libby Keir of Fernhill Heath has duplicated the "Newsletter" from No. 2 onwards with unfailing cheerfulness and now regards herself, quite rightly, as a "semi-skilled" 714" Gauge expert! Lastly the Editor's family has from time to time developed "envelope licker's" tongue and writer's cramp when the Newsletters were ready to post, and his wife has typed his illegibly written editorials, suppressing the temptation to put them into proper english!

WHERE ARE THEY NOW? Rodney Weaver

The new questionnaire prepared by David Walters may reveal the existence of some hitherto unsuspected early — perhaps historic — 7V4in. locomotive, so it was thought that an occasional series devoted to notable locomotives built during the first quarter of this century might be of interest to our newer and younger members. At the same time, such articles might stir another member into completing the story of a machine that still exists in a dark corner of his garage! Having suggested the basic theme of the series, I had to "volunteer" to write the first one, so I have chosen one of my favourite designs from the pre-1914 era, Henry Greenly's 1910 0-4-2 tank design for Bassett-Lowke.

Greenly designed this locomotive — the first 7!4in. design specifically intended for the smaller garden railway — at the request of H.F. Gerhatz of Bedford. It was designed to go round 25ft radius curves and to haul a load of about one ton on the level. As he did whenever he was allowed a free hand, Greenly built to "maximum dimensions" — his own words — with minimal concessions to exact scale reproduction. His 0-4-2 was not in fact based on any existing prototype, it was — like his Romney "Pacifies" of later years — an extrapolation of existing practice up to the limits of the scale loading gauge. 4ft long, 20in tall and 14 in wide it weighed 2841b in working order, of which about 2cwt was available for adhesion. The driving wheels were 7'/2in. diameter and the inside cylinders 13/iin. x 2Vi\n. with slide valves on top operated by Greenly's uncorrected valve gear. Noteworthy mechanical features were the use of piston rings, the massive single-bar crossheads and the marine big-ends. The boiler was of 5/16 steel with copper tubes expanded in place: the barrel was 7in diameter internally and the deep firebox provided 42'/i sq.in. of grate area. The tubes, 18in number, were V* diameter.

At a boiler pressure of 80 psig the nominal tractive effort was 651b. This is somehwat less than that of some more recent designs, but it was as much as could reliably be transmitted by the available adhesive weight. As Greenly's locomotive was significantly heavier than the aforementioned designs — and provided with more boiler power — the apparent discrepancy was no more than the difference between optimism and realism. Those apprehensive of locomotives fitted with injectors only may care to note that Greenly specified a single injector with no hand pump on all his 7!4in designs of this period. At least two of these handsome and practical garden railway locomotives were built in 1910/11, one for Gerhatz and another for Tom Foster of Burnage, near Manchester. The design was listed in Bassett-Lowke catalogues for some years, both as a finished locomotive and as a kit of parts, so there were almost certainly others. Where are they now?

CYLINDER DRAIN COCKS by C.R. Simpson

I have been very interested in the references in the News Letter to cylinder drain cocks, especially the letter from Mr. R. Weaver, which aroused memories. As he stated, there was generally no attempt at muffling where tracks were fenced. Where this did not apply, Steam jets were sometimes provided at the front of locomotives to scare cattle from the tracks; some American locomotives were so-fitted.

1 recall a demonstration of muffled drain cocks at St. Pancras station, many years ago. At that time there was a much greater need for such devices, for horses were abundant. Level crossings were often located near to platform ends and while the gates were shut across the road horses and horse-drawn vehicles would collect. Should the driver open the drain cocks when re-starting, the waiting horses could be relied upon to take fright, which usually led to much cavorting and indeed to accidents. The erstwhile Midland Railway regarded the matter as of sufficient gravity to warrant giving a trial to a muffling device and one of their singles was fitted with the equipment which consisted of a long tube, closed at one end, drilled along its length with a multitude of holes. This gadget was fitted, by means of clips, to each drain cock. In theory the steam passed into the expansion chamber and thence, via the many holes, to the atmosphere, the noise becoming delicately modulated in the process. So much for theory.

A crowd of interested people gathered at the platform end, the driver opened the regulator — albeit slightly ham-handedly and the engine developed a violent slip. This was long before the days of pocket-calculators and other such aids, so presumably the designer had worked out the hard way the number and diameter of the holes required to pass the likely volume of steam, but from subsequent events it appeared that violent slips had just not entered into his calculations. Be that as it may, the pressure built up within the silencers was sufficient to wrench them from the cocks and project them violently many yards down the track ahead of the train, which proveeded on its way. The idea of fitting them to Midland Railway locomotives did not proceed.

Drain cocks had uses over and above clearing the cylinders when starting. Enginemen were enjoined to always leave them open when an engine was standing. Failure to do so could result in a cylinder being cracked, or even a large piece being broken right out, if an engine was left overnight with the drains shut and the condensate froze.

I remember seeing a GWR engine, during the big freeze of 1963, arriving at Maidenhaed with icicles depending from the drain cocks. I would not have believed this to be possible had I not seen it.

1 was on an engine at Euston one day, when the drain cocks were left shut after it set back on to the train. Shortly before we were due away the engine and train started moving forward, though the regulator was closed and not leaking; as the carriage doors were open and passengers in the process of getting in, this caused some consternation! The remedy was to open the drain cocks. It was possible for pressure to build up in the cylinders of some LMSR locomotives due to steam entering the cylinders via the atomiser of the lubricator. The cylinder drain-cock operating gear was coupled to the

steam valve feeding the atomiser; failure to open the cocks when standing resulted in engines moving without warning, as when the cocks were shut the atomiser valve was open.

Air or steam-operated drain cocks made for simplicity, as it was much easier to run a copper pipe from the cab to the cylinders than arrange the rods, levers, and shafts. Provision of rod-operation on a large locomotive called for considerable care in design; it also added to the maintenance. A leaking cock could waste a lot of steam. Automatic cocks, spring-operated, opened when there was no pressure in the cylinder.

While it was customary for many engines to have three drain cocks per cylinder, the centre one communicating the steam chest, it is unusual to find this refinement on models.

A feature of cock nozzles on full-sized lovomotives was that they were inclined upwards towards the front of the engine. The purpose of this was to stop the issuing mixture of steam and water from throwing the ballast up.

Open drain cocks gave a very sensitive touch to the regulator. This was useful when setting back onto a train, and when it was necessary to move an engine very delicately — as when coupled to a breakdown crane requiring moving but a few inches.

One of the earliest engines to have cab-controlled drain cocks was the 'Superior' built for the Hudson River Railroad in 1854. One of the first — and possibly the first — British application of steam-operated cocks was by the South Eastern & Chatham Railway. Mushroom-headed valves were used. Steam-operated cocks were fitted on some of the BR standard locomotives.

Cylinder drains protect cylinders, pistons, piston rods, connecting rods, etc. Apart from draining condensate they should be used when water is carried over from a boiler. This latter condition is discernible audibly, by knocking developing and also by the sound of the exhaust.

I think it was LB&SC who originated the idea of operating drain cocks on a model by a Bowden cable working inside a copper pipe — it is a good idea.

71/4"/7'/2"GAUGK IN U.S.A. by Wm. F. Whitman

Live steam as a hobby in the United States probably got its first big boost with the formation of the "Brotherhood of Live Steamers", an organization founded by Carl A. Purinton in 1932. Early live steamers built in 2Vi", 3 Viin and4'/»" gauges with little interest in the larger 714" gauge. However with the passing of time there was a drift towards larger scale locomotive models. In the U.S.A. today over 65% of all new track laid and over 65% of all new locomotives under construction are for 714" or I'/i" track.

The American controversy over which gauge to build in, 7V4" or 7Vz" has been going on since a major supplier, "Little Engines" of Lomita, California first came out with plans and castings to the wider track gauge. This has resulted in the original 7!4" gauge holding out in a few of our north eastern states while the balance of our country has gone over to the new TYi" track. In the opinion of the writer this is a most unfortunate situation and one that will not be resolved completely in the foreseeable future. Even Canada, our neighbour to the north has tracks in both gauges although 7 4 " gauge greatly predominates.

Most U.S.A. 714"/7'/2" gauge live steamers are into 1 Vi" scale with only the occasional narrow gauge, larger scale prototype making its appearance. In many areas of our country the battery-electric motor operated and the internal combustion driven locomotives have taken over the 7!4"/7!/2" scene, greatly outnumbering the steam driven engines. Contributing to this trend are the low cost, availability of kits, parts, ready to run engines and reduced construction time. Many of these switch on, switch off type locomotive operators were formerly into HO and other small scale locomotives. Their main interest is railroading and not live steam. For them the smaller 3 W and43/4" gauges are unsuited for passenger hauling. While the two groups share the tracks in harmony it is conceivable that a further great increase in non-steam driven engines could severely limit the use of the tracks by all, including those who fire their locomotives.

In America the7!4"/7 l /2" gauge tracks are generally longer than those in England. This past summer of '76 the writer visited a privately owned, non-commercial 7V4" gauge site, near Kalamazoo, Michign with two and a half miles of track. The ties (sleepers) were of concrete to reduce rail expansion/contraction and lessen maintenance. While such lengthy model railroads are the exception, it is not unusual to encounter those that are over half a mile. The sites of these tracks are generally privately owned by either individuals or clubs. This feature enables the enthusiast to use the track at a time that possibly would not be available if it were on municipal land and obligated to weekend public passenger hauling.

It is the opinion of the writer that most English built live steam locomotives pull better for their size than their American built counterpart. Generally the detail and finish is also superior. Unfortunately when it comes to the rest of the train the comparison is not so favourable. Our American freight cars (goods wagons) have the same attention to detal and exact replica scale as the locomotive receives and the track is made to resemble full size practice, only in miniature. In England passengers and frequently

the driver ride on trolleys that look more suitable for a carnival than a train. In the smaller gauges the English track is usually raised above the ground, making it most comfortable to ride but totally unlike the full size railroad. In the U.S.A. we have both types, ground level and raised for the 3'/i" and 43/i" track. Our llA"/lVi" gauges are nearly always at or near ground level like in England.

The writer has greatly enjoyed the publications of your 7!4" Gauge Society. As your appeal is world wide may I suggest adding IVi" gauge to your name. Hopefully this would not result in the IVS'/lVi" confusion we are experiencing on our side of thie Big Pond.

The A.G.M. of the 714" gauge Society at the clubhouse, M.D.S.M.I . Claygate Lane, Thames Dillon, Surrey, on the 17th and 18th September, 1977.

The A.G.M. will take place one week earlier than was advised in the last issue of the "News" the new dates are now 17th and 18th September, with the actual A.G.M. taking place at 7.30 p.m. on the 17th in the club house. Members are welcome to turn up at Thames ditton any time on the Saturday and have a steam up and run on the track prior to the A.G.M. Sunday the track is available to all members wishing to run their locomotives.

For those members wishing to come to the A.G.M. and make it a two day event, there is parking space available for caravans by the club house, and there is also room in the club house for those with just sleeping bags. For those who desire more comfort there is a very nice hotel approximately 3/4 mile from the track. The address is:

The Haven Hotel, Tel. 01-398-0023 Portsmouth Road, Esher, Surrey. KT10 9AR.

Members wishing to have accommodation at the Hotel please write direct to the above address. I have been advised that bookings should be made early as September is still a busy time.

The Maiden track is approximately V/i miles from Hampton Court Palace, which is well worth a visit, and would make an interesting afternoon outing for the ladies not wishing to spend all day at the track.

Nearer the date of the A.G.M. I hope to include a small map in the "News" to help members locate Claygate Lane.

Romulus gets around! above, at Echills Wood, Stoneleigh and below: on the Portway line. 1976.

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Open Day at Porters Hill Railway, 1976 (Brian Rogers) and below, Steam on the Saltwood line. (A. Scharb.)

Secretary s Notes

I should like to remind everyone that subscription renewing time is just about now. Subscriptions run out at the end of February (unless you are one of the prudent ones who have paid several years in advance). Have a look at the date written on your current membership card; if that lies somewhere in the past, it is time to send a cheque to the Treasurer or to me. The Treasurer is, I understand, looking in the best way of offering either a standing order payment system, or possibly a Direct Debit scheme. "Memory", as someone — I forget who — said, "is a device given to us to enable us to forget things". In view of this very prevalent phenomenon, either of these schemes would involve a Fail-safe feature, so necessary in all railway affairs.

In this Newsletter is a Form for you to fill in as best you can, and return to me. From your returns, I hope to be able to compile a Register of Locomotives. I think it is fairly straightforward; only include 7'A" orlVi" gauge engines. I hope we may, by the aid of the last two columns, be able to locate one or two locomotives of historical significance. All new members will get one of these forms with the initial documents.

I have just heard from the Chairman that the date of this year's AGM has been advanced by one week to Saturday 17th September. It will, as you know, take place on the premises of the Maiden Society, at Thames Ditton, by kind permission of the Committee of that Society.

David Walters

NEW MEMBERS SINCE THE LAST NEWSLETTER

184 J. Hawker 9 Buckland Road, Chessington, Surrey. 01-397 8610

185 Peter C. Haines 139 Common Road, Kemsworth, Dunstable, Beds. LU6 2PJ Whipsnade 872564

186 Graham F. Wheeler 23 Milton Road, Addlestone, Surrey KT15 1JB. Weybridge45727

187 Lawrence John Martin 'Wayside', Amsbury Road, Hunton Kent. Maidstone46125

188 S.R. Nightingale 7 Goddards Head, Salisbury Road, Andover, Hants. Andvr. 4126

189 W.J. Lillington Castle Mount, 17 Castle Hill, Maidenhead, Berks.

190 Peter F. Kirby 6 Birch Road, Burghfield Common, Readinc, Berks. B/Common 2555

191 Jack Meatcher 45 Marks Road, Working, Berks. Wokingham 79039

192 Frank B. Gittins

193 H.E.Richards

194 Reginald S. Wilkins

195 E.N. Morgan

196 Alex J. Duman

197 David A.Nicholson

198 C.R. Chandler

» 9 Lionel H.PIMM

53 Portland Road, Rugby, Warwicks. Rugby 74308 'Pantauhirion', Wern, Rhosesmor, Mold, Clwyd. Halkyn 411

18 Gallaghers Mead, Anoder, Hants. SP10 3BW. Andover4816

'Fircliffe East', Whitworth Road, Darley Dale, Matlock Derbyshire. Darley Dale 2722

8 Orchard Court, Thornliebank, Glasgow, Scotland. 041 638 6647

275 Atherton Road, Hindley, Wigan, Lands. Wn2 3PR

Station House, Bredon, Nr. Tewkesbury, Glos. Tewks. 72054

The Red House, 9 North Close, Ipswich Suffolk IP4 2TL Ipswich 52910

RENEWALS SINCE THE OCTOBER MEMBERSHIP LIST

001 Robin Butterell

031 P.J. Dupen

047 David Smallwood

057 K.J. Woodham

Laurel Farm, Priddy, Wells, Somerset. Priddy 265

Tilepits, Burnham Road, Woodham Mortimer, Essex. Purliegh 269

Orchard Bungalow, Chapel Hill, Lincoln LN4 4PZ. Coningsby 42414

2 Firs Close, Lane End High Wycombe, Bucks. High Wycombe 881198

058 I). Frampton

065 Frank James

071 Ken Rosewarne

077 D. de Smedt

084 R.G. Marshall

087 J.B. Hollingsworth

089 D.O. Cunliffe

Kill IS. Lillington

101 John Thorburn

120 Patrick Henshaw

121 A.F. Gosling

Hartlebury House, Benton Green Lane, Berkswell, Coventry, West Midlands cv7 7AX

Sytch Cottage, Astley Cross, Stourport-on-Severn, Wors. DY13 0RD. Stourport 6280

Leeds Grammar School, Moorland Road, Leeds LS6 IAN

Elginridge, Church Lane, Bulphar, Upminster, Essex. Grays Thurrock 891486

15 Lindisfarne Road, Amble, Morpeth, Northumberland NE65 OEH. Amble 233

'Creua', Llanfrothen, Penrhyndeudraeth, Gwynedd. 076 674 534

Old Place, Sutton Valence, Kent. Sutton Valence 2377

Ashley Lodge, West Drive, Sonning, Reading. RG5 4RD

Viewfield, Station Road, Duns, Berwickshire, Scotland.

10 Wyke Oliver Road, Preston, Weymouth, Dorset. Weymouth 833044

18 Southville Gardens, Kingsbridge, Devon. Kingsbridge 3402

126 Maurice Clifford No. 1 Silver Band, Knock, Appleby, Cumbria. Kirkby Thore338

TRADE TOPICS

The next issue of the News will see the start of a regular item called 'Trade Topics'. This feature will contain information about firms who sell, or make items for 7',4" gauge railways, including those small, one-man shows that provide a specialised service such as a willingness to produce one or two casting from Members' patterns, or carry out those machining jobs for which Members' workshops are not equipped.

Some of the most reliable sources of information are the recommendations of Members; so, if you have had good, reliable service from ANY firm, please let me have details as soon as possible. Details that I receive will form the nucleus of a 'recommended list' which will be published in the next News.

I shall also be compiling a list of all suppliers of drawings, castings and materials with details of their wares. This will take time, but again Members' assistance is welcome. To begin with, I shall be contacting those firms who advertise regularly. However, in the current economic climate, it will be pointless publishing a comparative price list.

Please send you contributions on this topic to me: Don Fifer, Withnell Starion, Abbey Village, CHORLEY, Lanes. PR6 8DA. or telephone (but please don't reverse the charge!!) on Brinscall (0254) 830900.

PROGRAMME

Please note some alterations to the programme printed in Newsletter No. 10. May 14§15th TA" Gauge Society invited to Echills Wood Railway, National Agricultural Centre, "Royal" Showground, Stoneleigh Abbey, Warwicks. June 5th Open Day — Porters Hill Farm, Ladywood, Nr. Droitwich. 10 a.m. — Dusk (O.S. Sheet No. 130) Map ref. 864604). Telephone Worcester 52397.

Late June Possible visit to Hilton Valley Railway (to be confirmed). July 17th Open Day — Portway Light Railway, Merryhill, Portway, Upton St. Leonards, Glos. (O.S. Sheet No. 143 Map Ref. 872141) Telephone Gloucester 66244.

September 10/1 lth Echills Wood Railway, open for visitors from outside clubs. Runnig time for 7 14 "G. members also. September 17/18th By kind invitation of the New Maiden Society at their track at Claygate Lane, Thames Ditton, Surrey. Open weekend for the Society, including A.G.M. in the Clubhouse on the 17th.

Once again may we remind you that hosts at Open Days will supply tea and cold drinks, where possible, but all other catering must be arranged individually by those attending.

THE SPINNEY LIGHT RAILWAY by J. Ballantine Dykes

The object has been to build a layout which would provide interesting operating movements and a chance to run a railway system as nearly to full size practice as possible. Also, it has always been felt that a completely level track gives no opportunity to test locomotives and drivers.

As it happened the ground levels of our garden would have precluded laying a level track and gradients become necessary to limit underground penetration to a maximum of 13 feet and embankment height to a maximum of 6 feet. Cut and fill quantities had to come into the calculations and we managed to complete the engineering works with only a few cubic yards of spoil in excess of requirements. The 13 foot limitd for tunnels and cuttings was dictated by the reach of the backacting digger used to make the cut. The two tunnels, one 50 feet and the other 140 feet long are constructed as concrete and blockwork boxes with the sand spoil backfilled over the roofs. An added interest is discovered by new drivers when entering the long tunnel. This is that the summit of the whole line occurs about 30ft inside the entrance and unwary drivers can be caught by the change from 1 in 90 up to 1 in 70 down in the darkness of the tunnel.

Great efforts have been made to produce a first class track and we are lucky to have a solid sand subbase which gives perfect drainage. We spread a 4 " layer of Southern Region, B.R. reject ballast on top of the sand and rolled it well to give a firm, level and well consolidated stone surface on which to lay the heavyweight Cromar White alloy track. Regular maintenance of the fishplated joints and checking of line and level has produced a very smooth running track.

A look at the layout diagram will show that we have managed to include a circuit for continuous running together with facilities for end-to-end operation to and from Dingley Dell terminus. One circuit from and back to Dingly Dell gives a journey of approximately 2000 feet. Platform lengths are sufficient to take a locomotive and four 8'0" coaches and clearances throughout allow a maximum 22" width for locomovites and stock. The only loco which as defeated the system is Bob Jones' Colossus which cannot travel to Dingly Dell and which anyhow is too long for the turntable. This loco will clear the other platforms which are set back a further 2 " and we use the Triangle at Baytree Junction to turn her — a complicated manoeuvre involving "Shunting into Forward Section" and "Blocking Back outside Home Signal" which effectively shuts down the main line temporarily! But what a locomotive — she does not seem to notice the maximum 1 in 70 gradient and will haul all the stock I possess.

Spinney Station is a through station with a bay line for terminating and starting trains and a spare loco siding tucked away by the signal box — very handy for friendly and distracting conversation with a harassed signalman! Crossovers A and B are fitted with spring points so that drivers can run round trains on the " u p " line without having to leave their footplates to change point levers. Crossover C is lever worked from the signal frame. The working of all trains south of the Spinney Signal Box into the tunnel sections is controlled by the use of a token which must be carried by all trains entering the Section. It is only too easy to "forget" a train without this safety measure and anyhow, whoever heard of single line working without a token or tablet? I have completed the signalling for Spinney Station and have built 2" to 1 foot scale L.N.W.R. lower quadrant signals

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which are worked by lever from the signal box. This has increased the operating interest enormously and makes for safe working, provided visiting drivers obey the signals.

The level crossing across the driveway to the house posed a problem as the "down" line runs blind onto it from behind a laural hedge. The gates are always closed during operating sessions and to make things even more safe, we have inserted a track circuit into the down line to give an audible warning of the approach of a train.

Baytree Junction, called after one of my early and rare gardening success — the planting of a small bay tree cutting in 1958 which has survived my railway activities — has proved to be the hub of the layout. Situated as it is alongside the steaming sidings outside the Loco Shed, Baytree Station seems to generate "mothers meetings" and this is not helped by the fact that on hot days a tray of cool canned beer can always be found in the shade of the trees. All this easygoing behaviour by footplate crews will be brought to an end as soon as I can get the 19 lever electrically operated and electronically interlocked lever frame into operation. This Signal frame will control main line traffic through the Triangle and also Branch traffic into and away from Baytree Junction. The tendency to hold "parish pump" meetings at the water tower will, we hope, dissolve in the face of super-efficient signalmen in control of operation at Baytree Junction! Seriously, though, Baytree Junction should prove to be a most interesting station for signalmen and enginemen with many loco and train movements possible.

From the layout diagram Dingly Dell seems to have a simple track plan and to be a place for tired enginemen and out-of-breath locos. On busy days, when five or six locos are in steam, this terminus can provide hectic times for both signalman and loco crews, escpecially as Dingly Dell controls all servicing movements to and from the Loco Shed were coaling and watering takes place clear of the main lines. Trains are made up here and are altered to give variety to the locos. 1 know what many readers will want to know — why are not the sidings from the Loco Shed joined to the Dingly Dell siding with a right hand turnout to give better shunting and marshalling facilities? The answer is that this will be done in the near future when time and resources will allow. It is the one un-deliberate mistake I made when planning the original layout.

All that remains of the layout to be described is the Loco and Stock Shed. This is a wooden building with four tracks entering it at ground level. Inside, the floor level of the building has been lowered by 2 feet so that ash removal, maintenance, oiling etc. can be done that much more easily. The tracks are carried on Dexion framework and it is easy to prepare a loco for steaming without backache and sore knees.

As regards locomotives and rolling stock, the following is a list of items now running on the Spinney Light Railway:—

One 0-4-0 Hunslet Tender Loco built by Roger Marsh named "Emily" after my first grandchild.

One 4-6-0 Royal Scot Class Loco, pre-war Basset-Lowke and believed to be originally a runner on the Ken Wood Line.

One 4-4-0 L.N.W.R. George V Class Loco, also pre-war Basset-Lowke and believed to have the same history. This loco has been fitted with a new Tom Snoxell copper boiler.

One Cromar Whire 4 wheeled Battery Electric Loco, used for maintenance and shunting details.

Cromar White Narrow Gauge Wagons:— One Brake Van One Covered Van One Water Tank Wagon Two 4 wheeled Open Wagons One 8 wheeled Flat Wagon

In addition, I have three very fine scale models of L.M.S. express coaches and four scale wagons which were made by a Mr. Marks of Rickmansworth with a great attention to detail. They look very good and they run very well.

From all that I described, it will be seen that I am trying to create a railway that, in time, may be operated to full size rules and practice when the signalling and the communications have been completed. I hope it will provide more than just a track on which to run locos and it will give pleasure to the serious enthusiast who wants to help to run a railway. Many people have enjoyed the railway up to now; I hope many more will do so in the future — that is the fun of it all.

• • • • • • Our member, Andrew Smith, has widened our public image by writing a short article (with photograph) for SIMEC (Stuart International Model Engineers Club) Journal No. 30, about the Echills Wood Railway.

• • • • • •

MALDEN DEVELOPMENTS (FOR7/4" SOCIETY) by G.REYNOLDS

ITEMS:

Carriage Shed extension. Relaying of back curve on new alignment. Hope to do some work on Signal Boxes. Work on Clubhouse floor.

Work has been progressing down at Maiden during the winter months with several vital projects being on the Agenda. Two of these were linked with each other they were the building of an extension to our carriage shed and the re-laying of the curve that runs past the carriage shed.

The other two projects were somewhat thrust upon us which had to be done rather than need doing. These are the laying of a new clubhouse floor following a burst water pipe during the great freeze up which resulted in the floor starting to lift. It is thought to be the only floor which floated with the water level. Also the clubhouse needed to be painted and it was decided to do this before the floor was done.

An A-road extension to our present carriage shed is being built, the walls and roof have been built and it now remains to build the track work inside the shed and fit doors. The shed has been built so that it can accommodate narrow gauge coaching stock.

As members of the 7 !4" Society who have visited Maiden in the last two years can testify we have only had one bad section of track and that is the piece adjacent to the clubhouse, past the carriage shed through an S bend into the cutting next to the B.R. lines. This old track has been removed and excavations to prepare the way for the new alignment have been going on. This includes digging foundations for proper drainage and levelling, filling up with shingle as a base then laying granite chippings on this, then the track and more chippings.

Also incorporated in this plan is the re-laying of the carriage shed sidings as new track work was required to gain access to the extension. It is hoped to have all this work completed by Easter.

A new power supply has been obtained for the signal box and some mechanical point and shunt signal pull wires have to be replaced before the Easter Opening.

Member Pete Taylor of Cheltenham has just completed a fine model, accurate to 7 Win. scale, of a GWR Water Crane, complete with hose and chain and fully plumbed, with crank cock. The prototype was at St. James Station, Cheltenham, now dismantled.

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H.V.R.'s NEW CONSOLIDATION CLASS LOCOMOTIVE 'MICHAEL CHARLES LLOYD, M.B.E.'

The volume of traffic on the Hilton Valley Railway over the late 1960's eventually led to a decision to build a new locomotive to carry the increasingly heavy loads. The existing three steam locomotives had been hard pressed to keep up with the continual pounding every Sunday afternoon. Eventually diesel locomotives had to support the service and occasionally became the main prime movers.

The specification for the new locomotive was brief. It had to be large and powerful and preferably eight coupled for improved traction. If possible the locomotive should also be a scale model of a prototype, therefore it had to be as narrow gauge as possible. After much searching among old locomotive manufacturers' handbooks a suitable, if unusual, prototype was found which was built for the Andean and Bolivian Railways.

Originally many of the earlier Andean Railways were built in narrow gauge because of the sharp curves which had to be negotiated. The FCAB was started in 1873 and at one time had the highest section of any Railway in the world, extending to 15,835 feet above sea level. Locomotives were supplied by the NortrT British Locomotive Company and Hudswell Clarke; these operated until 1928 when the line was converted to metre gauge. Some of the 2-8-0's still ran at the Pacific termini, but eventually all were scrapped.

Using only the Works' photograph as a guide, work started in 1970 when M.H.P.A. LeVie (an ex British Railway designer who worked with many of the famous names in Railway engineering) designed the chassis and working motion. Using his experience it was possible to design a fully balanced engine without being inhibited by straight scaling of prototype locomotives.

All engineering was carried out by A.J. Glaze & Co. of Wolverhampton, which with his other extensive commitments took 5 years. The result was first seen at H.V.R.'s open day in June 1975 and since that time H.V.R.'s No. 9 has covered an estimated 400 miles and so far has pulled up to 120 people in one train with ease

Specification:

Cylinders Working pressure Boiler Wheel arrangement Tender Valve gear Tractive effort Overall width Overall height Overall length Minimum radius negotiable Gauge Scale Weight (F.W.O.)

4'/4"diax 5" stroke 80p.s.i. Steel 2-8-* (Centre drivers flangeless) 6 wheel — 45 gal. capacity Walschaerts 1,300 lbs 22 inches 40 inches lift. 6 inches 26 feet IV* inches V* 1.5 tonnes

FITS, LIMITS, ETC. PARTI

by C.R. Simpson

Fits, it has been said, are what mechanical engineering is all about. It has also been said that the art of locomotive building is to know where to leave the slack. Both statements contain much truth. Upon the correctness of the fits largely depends on the length of time an engine will operate between shoppings, its efficiency, and — most important of all — its safe operation. The reputation of a builder depends to a large extend upon the excellence of the fits for their particular purpose.

In industry, sight must never be lost of the fact that accuracy costs money, and close accuracy costs a great deal of money. Tolerances must therefore be no closer than are warranted. I recall a case where a firm of toolmakers was asked to quote for some slitting saws, to the drawing supplied with the enquiry. A quotation was received which was about ten time higher than the amount usually paid; upon investigation it was found that the draughtsman had specified a 0.001 inch tolerance on the width of the saw, whereas one of 1 /16th of an inch would have been perfectly acceptable. The drawing should, of course, have been checked.

For many years industrial drawings have specified the limits to be worked to, thought fifty years or so ago this information was not necessarily given. These limits indicate to the shops the class of fit required. One the drawing, close tolerances appeared as decimal dimensions; those sizes where close tolerances were not required were given in fractional sizes, and such dimensions were subject to the usual tolerances of the establishment. These were dependent on the class of work carried out, they could be ± 1 / 16th in.

The draughtsman, having decided the classes of fit involved on a particular job, obtained the limits from tables. These could have been produced by the particular firm but, latterly, were more likely to have been obtained from some of the published tables.

In the 1930's, the writier discussed with the late Percival Marshall the absence of limits from drawings published in The Model Engineer. Mr. Marshall pointed out that these would be of no value to the then average model makers, who had no facilities for measuring or working to close limits. He went on to say that very few of the lathes then to be found in home workshops were capable of working to 0.001 in, or less. Today the lathes generally met with are more accurate than was the case 45 years ago, and measuring facilities and techniques. In most home shops are adequate for most of the work undertaken, but the fact will always remain that fits depend on limits and limits depend on the ability to measure and achieve the required dimensions — plus a reasonably good surface finish. Failure to adhere to limits, apart from the mechanical effects, can have very costly repercussions for, in addition to the time lost when a 'waster' is produced, there can also be the loss of the casting or material. In full-size engineering a large casting, plus machining already carried out on it, may stand in at tens-of-thousands-of-pounds. The possibility of the whole being lost by an error in machining in the final stages just does not bear thinking about. This is one of the reasons why it is difficult to get operators for the really large machine tools, able to turn diameters of 25ft or more. Not everyone wants responsibility on that scale. When things do go wrong, today there are facilties for building-up, etc., which can come to the rescue very often, but

Summertime on the Portway Railway (N.Rainbow). Above Tom Smith Electric and below, Narrow Gauge visitor. Open Day 1976.

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Trackwork on the Portway Line in Gloucestershire. Above, Spur to the sheds and below Main line with shed branch to the right.

they are better avoided, for it is not everyone who will accept a job which has required rectification. As an illustration of this point, Beyer Peacocks built over 200 tram engines in the days when many tramways were steam-operated. One of these engines, when being off-loaded in the Southern Hemisphere, had the misfortune to be dropped into the harbour. Although it was straightened out, the customer refused to accept it and it was returned to Manchester. There it was employed as the Builders' works shunter for 80 years, prior to its going to the Crich Tramway Museum. Ironically, it had a very much longer life than the engines which did not get a salt-water bath.

Cylindrical fits are normally made on what is termed a 'hole basis', for most holes are produced by drilling, reaming, or broaching, and their size is not as easily altered as the component which will fit into them, termed the 'shaft'. In this system any required variation in size is made to the outside diameter of the shaft, the hole size remaining constant. There are some cases where a 'shaft basis' is employed, e.g. where a pin is hardened and ground and the hole is in relatively soft material; in such a case an expanding reamer might be used to obtain any increase in the whole size. Piston rods and valve spindles were among items dimensioned on a shaft basis but pistons were on a hole basis.

After the Nationalisation of railways in Britain, it was decided to survey the fitting practices of railway works, with a view to standardising them. Some amazing facts emerged. One works was giving sufficient clearance on new big-ends to call for their renewal by the standards of Swindon. It makes you think!

The British locomotive industry, soon after the last war, also reviewed its works practices and produced a standard code to replace the varying practices of its different works.

There had, of course, been British Standard Specifications, covering limits and fits, for many years, and some consulting engineers had produced their own tables — notably in connection with locomotives for India. The BSS specifications had not been formulated with locomotives in mind, though some of the needs were met. A locomotive is a very particular breed of machine, for where else can one find an engine, developing perhaps thousands of horsepower, where the crankshaft (in this case the crankaxle) bearings are not rigidly located relative to the cylinder, compared with which the shaft spends most of its time, when at work, wobbling about in the verticle plane?

The upshot of the industry's review was that the Locomotive Manufacturers Assocation Association produced a book on limits and fits, which were on both 'hole' and 'shaft' bases, the combination being referred to as a 'locomotive basis'.

There was by no means agreement on optimum limits and fits among locomotive engineers. The subject was a vast one and complicated. Scope of this article is confined to outlining the different classes of fit, and suggesting some limits (Newall) which will result in guaranteed fits. It must, however, be remembered that while the limits are easily obtained by grinding it is not easy — in fact sometimes impossible — to obtain a limit of 0.001 in, let alone less by turning in a lathe, unless it has special precision.

All this is given as background information; it need not frighten anyone, for all builders of models are already, consciously or unconsciously, involved with limits, the difference in doing it in an organised manner is that results can be predicted and time and material are not so likely to be wasted.

The writer has for over 50 years used the Newall Standard Table of Limits. This table will be found in many engineering handbooks and was — and probably still is — obtainable in the form of a small chart. Its use enables diameters to be instantly determined for force, driving, push, and running fits. It eliminates trial and error — which can sometimes result in error mainly! The chart in the writer's workshop covers all diameters in stages up to 12in. No workshop, producing parts which must fit each other, should be without such a table. There are, of course, others but that named is excellent and very easily comprehended.

No one need be put off by the fact that dimensions are given to five places of decimals, for the last two places indicate quarters, halves, and three-quarters of 0.001 in, and it is not difficult to read such fractions on a micrometer which has the thimble graduated in thousandths.

There are many aspects of locomotive work to which these tables will not apply, for they relate only to roundwork. Exceptions which come to mind are axle and crankpin centres, these in the author's opinion, should always be made with the greatest degree of accuracy of which the builder is capable.

Among factors affecting fits are rises in temperature. By far the most important of these is the clearance to be given between a safety valve and its housing. In full size practice failure to allow sufficient clearance has resulted in boiler explosion. It is a peculiar fact that when a safety valve sticks the driver, noting the pressure gauge trying to go round for the second time, always reports the gauge as out of order. In the case of an explosion of a London & North Western Railway's locomotive, at Buxton in 1921, it emerged at the enquiry that four different drivers had reported the gauge out-of-order, whereas it was the safety valves sticking. They should have picked this up, for all had experienced difficulty in getting the injectors to work, a result of their not being designed to operate far above the blowing-off pressure.

The reason why gauges were suspected instead of safety-valves was because gauges were much more prone to go wrong. Safety valves, when booked for attention, almost always required adjustment because they were reported to be 'light', i.e. blowing off early. At a shed such as that to which the engine belonged, there would probably be 50 entries in the report book, correctly calling for gauges to be changed, for every one relating to safety-valves.

Another example of danger arising from insufficient clearance is to be found in axlebox clearance in the horn. This led to the derailment, with very serious consequences, of a Liverpool-Euston express at Weedon in 1957. The engine, a Stanier Pacific, had had the bogie axles changed round, as the left leading bogie wheel flange had worn sharp. Unfortunately, the axlebox on one side, when changed, was too tight in the horn and when box rose it remained up, relieving the tyre of the pressure required to keep it in contact with the rail head and producing a situation which is always potentially very dangerous.

Seizure of an axlebox in the horn could result from a box running hot and expanding to such an extent that the initial clearance was more than taken up. Evidence that this had happened was forthcoming on the footplate in the form of excessive vibration. If wedge adjustment was provided on the horn, the box was usually easily freed by slackening it back. If that did not free it, or if there was no wedge adjustment, the box had to be cooled by

pouring water over it, and possibly also paraffin and oil. To start the box working in the horn again, a smart and considerable blow was necessary. That could be provided by running the wheel concerned over a fishplate placed on the rail head; if no fishplate was available the coal hammer head could be used. Should all these measures still fail, the engine had to be worked very slowly to the nearest point at which the train could be given up.

Things were not always what they seemed to be. Most people would think that top and bottom slidebars were always parallel, but this was not so when the engine was cold. Measurements would then show them to be spaced some 0.008in wider apart at the back than the front, assuming that they were attached to the cylinder cover at the front end. Even so, sheds sometimes found it necessary to make further provision for expansion. This was done in the case of the Royal Scots by leaving the front ends of the top bars slightly slack. If the nuts were fully tightened the top bars broke.

Limits vastly reduce assembly costs and enable parts produced in widely-separated plants to be assembled easily. This was very noticeable in the last war, when locomotive work was undertaken by firms which did not previously carry it out. In some instances a locomotive could embody pieces produced by over 40 different works, their assembly producing no problems. This would have been impossible in the absence of correct limits.

Where accuracy of a high order is required, measurements have to be taken at a standard temperature. This accounts for reliance on artificial lighting in some modern works — the sun cannot interfere with measurement to the same extent as when windows exist. Most countries have adopted a temperature of 20° (68CF) as the standard for precision gauging, as that temperature normally conforms to average working temperatures. It follows that for really accurate work — such as jig boring — not only the workpiece and the gauge, but also the machine tool must be maintained at that temperature. Such considerations do not affect home workshops, but readers may be interested to know of them.

There are, however, instances in the home workshop when the workpiece may become appreciably heated during machining. If this occurs and the part is one subject to close limits, it should be allowed to cool before measurements are taken with a micrometer.

Works are now maintained at more humane temperatures than was the case in the old days. Entering a shop on a Monday morning in winter one found many things frozen. The writer recalls an instance when a cylinder and piston were returned to the machine shop by the erecting shop, on the grounds that they were not machined to size. The cylinder was standing on its end and the piston was placed in the bell-mouth, where it rested for all to see that it would not enter the bore. While the inquest was in progress there was a loud thud, the piston having fallen in. This was due to the ring expansion of the cylinder when the shop temperature rose, albeit but very slight.

It is important that it should be understood what is implied by the terms used to define fits. Those which are encountered in the home workshop are:— force fits, driving fits, push fits, and running fits. The last-mentioned may be further broken down into (1) easy fits, (2) those for high-speeds and good average machine work, and (3) those for fine tool work.

Force fits — sometimes called pressure fits — are those where a cylindrical part is forced into a hole of slightly smaller diameter. A crank-pin or a wheel of an axle are examples. The allowance, per inch of shaft diameter, over and above the nominal diameter of the hole, is usually

from 0.001 in to 0.0025in, but tables should be consulted to obtain the exact allowance for any given diameter.

In some shops the allowance remains practically constant at all diameters, but in the larger diameters increased pressure will arise when forcing the shaft into the hole, due to the increase in surface area of the parts concerned.

Forced fits require greater pressure when assembling than drive fits. In the home workshop, in the absence of a press, this may be obtained if a sufficiently large vice is available. In the case of bushes, etc., the solution may be drawing-in with a bolt.

Drive fits, as the name implies, are those where the shaft is slightly larger than the hole and the allowance permits of the one being driven into the other. Such fits are employed where the shaft and the hole are to remain in a given position relative to each other. Some locomotive shops draw a distinction between heavy drive-in fits and light drive-in fits, the difference in the amount of force imparted being determined by restricing the weight of the hammers supplied.

The bolts holding the cylinders to the frames were examples of drive-fitting. Despite this class of fit being employed, keeping large cylinders tight on the frames presented great problems, solved in American practice by casting — in steel — the cylinders integral with the frames. An interesting means of relieving these bolts of shearing strains was to be found on the British Railways locomotive 'Duke of Gloucester', where strips, welded to the frames, butted against the flanges at each end of each cylinder.

It will be understood that in the case of both force and drive fits due regard must be paid to the amount of metal around the hole, the kind of metal involved, and the surface finish of the shaft and hole. In connection with the kind of metal, in full-size practice, for all sizes of axle the Industry's pressing-in allowance into cast-steel wheels was 0.001 to 0.002in per inch above the nominal axle diameter. This would require a pressure of about 8 to 12 tons per inch of axle diameter. For cast-iron wheels a pressing-in allowance of 0.0005 to 0.0015in per inch of axle diameter was made by some builders, this produced a pressing-in tonnage of 6 to 8 per inch of diameter. Bores in steel wheel centres wee were parallel, and axles sometimes so but frequently tapered 1 in 500. British Railways practice was to use a minimum pressing-on pressure of 10 tons per inch of diameter and a maximum of 12 tons for steel centres, and an average of 7V4 tons for cast-iron centres. The pressing-on lubricant was usually specified; that was important, for juggling the lubricant could considerably affect the pressure required and could result in higher pressure being necessary than the particular dimension warranted. Talking of juggling, it is not a bad idea, should an interference fit a shaft — which for these purposes includes the outside diameter of a bush — come out slightly undersize, to knurl it.

As many a builder of a model locomotive has found out — the expensive way — it is quite easy to split a wheel centre if the axle is too large; these modern adhesiyes have their advantages for securing wheels on axles.

Surface finish is an important factor in fits; a ground finish, while theoretically producing a greater contact area than a rougher surface will

give a lower pressing-on pressure. It was not unusual, when axles had been ground on the wheel seat, to use a smooth file to break up the surface slightly. In connection with that practice, I recall Sir William Stanier saying that he was brought up to believe that if he put a file on turned work he would go straight to hell!

A new 714" gauge locomotive design is offered by Messrs. Reeves. It is hoped that a review of the design will be included in a future copy of the News.

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Apologies are due to Mr. A.C. Schwab for giving the length of this track as 3.8" — this should have read "3/8 mile"! Even the Guinness Book of Records would be surprised at a railway only half as long as the gauge.

CORRESPONDENCE

Dear Brian,

Nigel Rainbow's letter regarding the accident on the P.L.R. was interesting and was a timely reminder that even on the best regulated railways one cannot relax vigilance when an intensive passenger service is being workd. One or two additional questions spring to mind when the letter is read by one who is not familiar with the operating procedure on the P.L.R.: a) Assuming that the electrical fault mentioned affected the signalling

system, was the second train admitted to the occupied section by a false''clear"?

b) Again assuming a signalling failure, what steps had been taken by the driver or other train crew to protect the first train in rear?

c) Was the brake power of the second train adequate to deal with the emergency which faced its driver?

The drafting of a comprehensive Rule Book was an early priority on the Echills Wood Railway and in preparing this it was necessary not only to study the characteristics of the EWR itself but also to study the thinking behind the Rule Book adopted by main line companies in this country. It is easy to draft rules covering what ought to happen, but such rules are of limited value. One has to imagine all the situations that could arise and ensure that your code of practice covers these as well. Elaborate thought it seemed when first issued, the EWR Rule Book still has considerable room for improvement becauseu learn something new about railway operation every time you run, and one must not be afraid to learn this way or else you may learn a lot very quickly by having an accident. The RCH Rule Book went to great lengths to cover the protection of trains standing at signals, and for good reason — many of the most serious accidents both at home and overseas have involved a standing traing inadequately protected — one has only to look up the circumstances of the disasters at Abbott's Ripton, Hawes Junction or Ais Gill to discover this. The P.L.R. accident was therefore a classic form, (hence my first two questions above) and it would be interesting to read the results of the enquiry into it. The matter of protection in rear is, incidentally, another good reason for carrying a guard on all passenger trains.

by Rodney Weaver

Associate Member Lynton Challoner has evolved an interlocked electrical signalling system for ground level tracks. A neat control console showns 'On' and 'Off for each signal, the Amber being automatically brought in appropriately. A mock up was used at an open day last summer.

Member Ted Hayward is at present completing cladding and painting of Nigel Rainbow's 'Mogul'. The loco has run for several years unclad on the PLR, and the work will result in a smart looking machine to partner Tom Smiths electric M.U. on the line.

Precision Paints Co. Ltd.

News of a new BOILER INSULATION The most common material used for model locomotive boiler insulation, is asbestos. This is not a true insulator, but rather a heat resistant material. The difference is profound!

With the recent adverse publicity concerning the dangers associated with the use of asbestos, and the necessity of using some form of insulation to preserve the boiler heat and the paint f i lm, we have been prompted to introduce a new insulation material for the model engineer. This material, though more expensive than asbestos, has a number of distinct advantages: firstly, there are no known health hazards; secondly, it is one of the finest insulants used in industry. It is easy to use and comes in three thicknesses.

Send S.A.E. (9" x 4") for details of paints and other materials to:

PRECIS ION P A I N T S CO. L T D . P.O. Box 43, C H E L T E N H A M , GLOS.

TRADE ENQUIRIES WELCOME

Plates presented by the Society to locos running at Rail 150 7%"g track.