Javascript is required

A web-site by Rob Speare


Building an Original 'Air-smoothed' Merchant Navy class locomotive

Words by John Lloyd.

My interest or should I say my fascination for Bulleid Pacifics started when I was about eight years old, after getting my first push bike and being able to cycle the 1½ miles to the nearest railway station at Swaythling.  We also used this station to go to Eastleigh to visit my Grandmother.  Approaching Eastleigh station by train, we passed the running sheds with all the locos standing outside.  It was easy to spot a Bulleid Southern pacific because of the bright green paintwork and vivid yellow lines down the sides.  But most exciting was the sight of one at the head of a train speeding along, a real eye catcher.

Anyway as time went by, I found out more about them from a library book that I believe was the first book to be written about this class, and my interest grew even more.  I used to visit Southampton Central railway station where all the Bulleids used to stop, and always filled up with water.

You could stand right up close to the loco and watch all the activity, and see the driver struggling to pull away without slipping.  They always seemed to exude power and those wheels always fascinated me, and I still think they are the best looking wheels on any British loco.

Time went by and I started 5 year apprenticeship at a ship repairing company as a fitter in Southampton docks.  We had every trade one can think of in the yard, well over 20 different ones, so any thing was possible.

Anyway after building a simple stationary engine without the use of a lathe, I thought it was time to start something more ambitious and worked out a plan to make a 2½ inch gauge Merchant Navy loco.  Needless to say all the materials were at hand, and I had a design worked out that I was confident would work [I was 17 at the time].  I made a pattern for the wheels and for the cylinders which were cast in the firms foundry.  The loco had 3 cylinders all with slide valves driven by 2 sets of Stephenson’s valve gear and conjugated gear to the inside cylinder.

After another year I was transferred to the outside fitters gang to do 2 years on the ships, which meant very little possibility to do much in the way of model engineering.  At about this time I joined Southampton model engineering society and had the use of a machine shop belonging to the father of one of the members, so I did manage some work now and then.  The last year of my 5 was spent back in the fitting shop, and we had the chassis running along the woodblock floor connected to the air line.

I then started on the boiler but before that could be finished I had to go to sea in the merchant navy or do National Service.  The tender was part finished while I was at sea, as all ships have a small workshop attached to the engine room.  After 2 years, National Service stopped, so I left the sea and ended up back at the firm I had served my time with.

My first priority was to build a bench drill and a lathe, both with the help of the firm I worked for, though of course they didn't know it !

So work stopped on the Bulleid, and I actually sold it to a British Railways fireman who was also a Bulleid fan, I don’t know why I got rid of it, but by then I was building a 'Tich'; but I do know that I regret it now.

So on to the second attempt which I started in 1975.  By then I had a fully equipped workshop and worked in a different factory, they had no workshop but plenty of materials though, especially copper !

I was introduced to a chap in Rainham, Kent who had built a 5" gauge West Country class.  Four of us visited him and had a drive of it.  He lent me the pattern for the wheels and cylinders.  I was also introduced to a retired ex draughtsman from Eastleigh Works who lent me about 20 drawings in microfiche format, which I was lucky to be able to get blown up to a decent size approx 24" x 16".  Work progressed slowly with several delays, but lots of information was amassed over the next few years which enabled me to get most things as full size.

I managed to get the chain valve gear in after a lot of drawing and head scratching.  One problem was getting the die links in side by side with their support brackets and radius rods.  The answer was to put the pivot pin of one link inside the next one to it; also the frames on these locos are closer together than other classes.  The steam reverser was made well over scale so as to give plenty power, as the die links rock at a steeper angle than normal in order to get the required valve movement, and of course it has to move 3 of them.

The valves are as full size, driven from within the valve chests.  They were originally made of stainless but were changed to cast iron after I had the liners lapped.  Getting the oil bath oil-tight has not been 100 percent successful, but one filling is sufficient for a day’s run.  The oil is pumped through various pipes and drips down on every moving part, 40 in total.  When the cover is removed, all the parts shine.  The pump is driven by an eccentric on the rear axle.

There are 9 cylinder drain cocks, 3 of which drain the valve chests; this requires rather a lot of linkage but everything seems to work OK.  Working dampers were fitted but only one set of linkage is still connected up, and the dampers are left open all the time.

Originally there was only one thermic syphon fitted but on testing the boiler there was a leak right behind it which made sealing it impossible.  A home made cutter was used to cut it out, the leak was sealed, and 2 smaller siphons fitted which are held in by unions and can be removed quite easily.

To make sure that the linkage inside the valve chests get plenty of lubrication, each cylinder has its own lubricator with pipes to each end of the valve chests, with pipes of exact equal length so the oil doesn't go to the path of least resistance, the valves being outside admission.

The Bulleids have a very complex braking system with double linkage everywhere, and 24 brake blocks altogether on loco & tender.  The loco brakes are steam operated, but for some reason will work on air but not on steam.


The loco was first run in 1999, but over the next 7 years I made countless alterations and have a mass of redundant pieces, and the loco now runs OK.  But it is like the full size in several ways, heavy on coal and water and the biggest problem, slipping, which takes place when the cylinder chest pressure reaches 60lbs sq in.

All in all I am very pleased with the loco which I named "Union Castle Line", as the ship repair company I served my apprenticeship with - 'Harland & Wolf' - built most of the Union Castle Co. ships, and I also sailed on 4 of their ships.

So irrespective of their faults and short comings, to me they are beautiful locos in their original form, especially the first 10 which were different from all the others, and as they say, beauty is in the eyes of the beholder !