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#361
21-09-18, 18:50
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In the scan of the Finnish manual that has exploded diagrams of the corrector and sights on pages numbered 34 and 35, there are lines leading to a set of 'U' numbers... ie U1 to about U48. Is there a key where these 'U' numbers (presumably part or component numbers) are listed and described; if so, would it be possible to get a scan of that please ? Thanks in anticipation Richard 
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#362
17-10-18, 16:10
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On another tack.... we've been looking at the electrical wiring that is on our Bofors. A lot of it is for lighting; this is run off a 6v battery and the wiring and connectors are all (naturally) low current. We can trace the wiring runs pretty well.
However..... there are some items we are not sure about. There are a couple of heavy-duty pin sockets just to the left of the ejection chute; one has a lead that goes into the centre of the revolve drum, and another lead that goes to a pretty chunky brass brass socket that is positioned just left of the ejection chute. All this is totally separate from the lighting wiring, and we have no idea what it is all for. It looks like you would plug a power supply into one part of this, and some device that needs power into the other; we have no idea why one lead goes into the revolve drum, as it is inacessible and has not electrical brushes on it. The gun is all manual.... no electric motors anywhere. I'll post some photos below. Any ideas anyone.... ? Incidentally, from info in the Terry Gander book we now believe that 'our' gun was made in Poland in about 1942 (but to the 1938 design) and was shipped to Portugal.
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#363
11-12-18, 18:21
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On another tack.... someone mentioned that the Corrector had a habit of turning as the gun traverses. Ours does the same.... we are now pretty sure we know why this happens, and that it is deliberate. If anyone is interested let me know, I'm happy to explain.
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#364
20-12-18, 15:09
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Another new question... we have to replace or retemper the set of balance springs that support the weight of the barrel when it is elevated. [They are housed in the two cylinders that sit below the barrel]. Unfortunately, we dont know how 'springy' the springs should be. I gather this is expressed in engineering terms as the 'spring rate' and is the weight required to compress the springs by one inch.
Does anyone have any technical info about the characteristics of these springs, especially the spring rate value ?
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#365
20-12-18, 17:14
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I can't say for sure in British gun terminology, but in North American terminology they are equilibrator springs. Basically you tension them until you have easy, almost balanced, elevation from level. Since there are two in this case, you will balance them left to right.
I was just involved in doing this with a M109 the other day, although they are equilibrated by hydraulic/nitrogen pressure. If you need to know the length of new springs, I believe I have some at home, and there may even be one or two kicking around this museum.
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#366
21-12-18, 14:40
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Hi Rob, many thanks for your reply.
Unfortunately... the springs in our equilibriator are already adjusted to the maximum possible, and still dont balance the weight of the barrel. Hence they need to be retempered or remade... but we of course need to know the spring rate to temper or construct them to. Any chance you could place a known weight onto a spring (held vertically) and measure the displacement ? We could work out the rate from that. As is the way of things I cant offer much by way of returning the favour.... though if your gun has the Bofors Speed and Course Sight fitted (as does ours) then I can share with you our discoveries about how it is used... Thanks and best regards Richard
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#367
16-03-19, 12:24
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General update about the Bofors at The Shuttleworth Collection in the UK. ....
.... after much huffing and puffing we successfully removed the six balance springs from the gun, discovering along the way that one was broken. Our friendly spring factory says that they cannot be retempered (as they cant tell what material they were made from or how they were made in the first place), and also says that they cant make new ones using rectangular-section strip. So... does anyone know of a source of unused balance springs, or has anyone successfully made replacement springs from round section strip ?
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#368
21-05-19, 21:20
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Rob Fast's Bofors # 201
Quote:
https://en.wikipedia.org/wiki/Stellan_Bojerud I had the benefit of talking with him about the Bofors guns many years ago and have continued my research in Swedish archives. What I actually knows is that Sweden managed to get a contract for 68 guns from Hungary in spring of 1938. Hungary needed Dollars to import other arms and thus expanded their licence production for export orders the years before the war. (as did Poland) At the same time Bofors of Sweden produced more guns for export than for the small Swedish order with a Serial number range from 1 - 100. Actually Swedish private donations accounted for more guns than the governmental orders in 1939. This Hungarian contract was above and beyond the Swedish long term plan and budget. But Swedish prime minister Hansson promised the Procurement agency they could count on new money for the next fiscal year, so they dared to sign the order. The Swedish designation was 40mm Akan m/38 and at least in 1945, the guns where branded as Bofors and not MAVAG. Serial number range for those guns that remainded in Sweden Autumn 1939 where from 208 - 268. On the other hand there where no planned organization for these guns so the bottle neck on Swedish side was officers and trainers. While we had enough Bofors guns to keep the trainers busy. So a significant number of the new guns where stored waiting for a crew. In 1937 Finland had started to set up their own licence production of Bofors 40mm at the state gun factory "VTT" but setting up a new factory took time and the optimistic plans where delayed numerous times. A few months after the Swedes Finland also made an order in Hungary of 30 guns. These where to be delivered later and from Swedish experience the Finns wanted to start training as soon as possible. Sweden passed over the first 8 guns to the Finns as a loan early 1939, and the Finns started training crews. On the 23 September 1939 the first Hungarian guns from the Finnish order arrived in Sweden and instead of moving guns between the countries again. Sweden took the new Finnish ordered guns with serial number 1 to 8 and Finland kept the Swedish guns which I assume are numbered 201-208. To confuse matters Sweden renamed gun number 1 to 8 to 201 to 208 in October 1940, So you have to look at the actual document from the period to make sense of it. So in short - I feels pretty sure that your gun was bought by Sweden sent to Finland in spring 1939 and remained there until post war. Kind Regards /John T Stockholm
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#370
22-05-19, 06:09
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John, that is sad news regarding Stellan.
We communicated by email regarding Australian/Commonwealth Bofors guns and AA equipment, a conversation from which I'm sure we both benefitted from and enjoyed. In post #59, Stellan was interested in this Carbon Arc searchlight: Quote:
While it was lit to commemorate Armistice Day, the next opportunity we will salute Stellan too!
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#371
18-03-20, 18:11
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1-ton 2 wheel GS trailer, popularly know as the "Ben Hur" trailer
Quote:
This text is not entirely correct: 1-ton trailers were not used with Jeeps, nor was the "F60B converted to SP units and the trailers re-allocated for further use" - the F60B was a SP unit from the onset.
__________________
Regards, Hanno --------------------------
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#372
17-08-20, 19:27
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I have just joined the Forum to research the Dome Trainer. This was the first anti-aircraft simulation technology invented by my grandfather, Lt-Commander Henry Stephens, for the Royal Navy in 1940. This is the Pathe News in 1951.
https://www.britishpathe.com/video/dome-trainer Henry's private journal has been deposited in the Imperial War Museum and the BBC made a documentary in 2025, narrated by the British actor Stephen Fry. YouTube has parts of the documentary. There was a huge demand for this technology with 43 domes being built across the UK including one at Langham which survives today. This puzzling dome structure was a forerunner of today's immersive experiences including Imax screens, aircraft pilot simulation and computer games. This revolutionary invention saved thousands of lives and shortened the Second World War. https://www.iwm.org.uk/collections/i...ect/1030031411 https://www.bbc.co.uk/programmes/p02rcd2x https://www.bbc.co.uk/programmes/p02rc8dl I would be pleased to have any more information on the Dome Trainer and the gunnery used inside it. At Scapa Flow there is a further installation of what looks like a rear gunner turret developed for air-to-air gunnery. This is not in any of the official records that I can find! Best wishes, Ewan Ward-Thomas Grandson of Henry Stephens, RN
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#373
15-04-22, 00:24
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This is a hugely informative thread and has been very useful to me in identifying a 1937/39 Instructional model of the 40mm Bofors that I am trying to restore. I think the model, like most instructional models used by the British Armed forces, was made by Bassett-Lowke, it is made of brass and is about 1/8th scale. From the information I've gleaned from Terry Gander's book and the wonderful information in this thread I think I've identified the model as a Mk I Bofors on a Mk I carriage, possibly Mk IA (Polish Carriage). The model also has the "Bofors/Polish Course and Speed Corrector" although parts of it are damaged/missing.
I was heartbroken half-way through the thread to discover that Stellan had died, especially so as he was a real driving force in learning new information about the Bofors and also the prime mover in keeping this thread alive. In one post he indicated that he was preparing a book on the Bofors, does anyone know how far he got with that and if anyone has taken it on after his death? In one of his earlier posts Stellan showed a photograph of some girls with 40mm Barrels and wanted to know which factory this was? I think there's a high degree of probability that it is the 'Hush-Hush' factory that was in Tubney woods just outside Abingdon. The manufacture of the barrels was re-located here after the Coventry factory was bombed. Article on the subject here: https://www.heraldseries.co.uk/news/...elped-win-war/ On the subject of the wheel nuts, Terry Gander's book, page 49, indicates that the Mk IA (Polish) Carriage's are identifiable from five bolts on the wheel hubs. However, earlier in this thread Stellan indicated that it was the Swedish made carriages that used five wheel nuts and the Polish carriages that used six? Does anyone know for sure? Certainly on page 21 of the Gander book there appears a 1938 photo, taken in A B Bofors workshop, which shows a 1936 model Bofors, ultimately destined for Dutch East Indies, which has five bolts on the wheel hub. This would seem to indicate that Stellan has it correct and that Gander inadvertently transposed the numbers, or did the 1936 model simply involve a re-design to the Polish style? There doesn't appear to be an option to upload images to this site so I'll have to look into getting some images up on a web hosting site so you can see the model. Last edited by Pete M; 15-04-22 at 02:51.
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#374
15-04-22, 01:10
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Another quick question regarding the mounting places on the Mk I carriage for the Ground Spikes. On the photos I've seen so far there are two ground spikes mounted, side by side, on the side of the cruciform just to the right of the Travelling Lock for the Gun. I presume there is at least one other, or possibly two ground spikes, mounted on each of out-rigger arms as well?
You can see more clearly what I am talking in photographs of this Dunkirk survivor at IWM. If you look at the second photo, just behind the left-side wheel you can see two Ground Spikes mounted on the side of the carriage, one pointing left and the other pointing right. There's a third ground spike visible on the out-rigger arm. https://www.iwm.org.uk/collections/item/object/30025446 On the model I have there are a total of three ground spikes mounted on the carriage. One of each out-rigger arm and a third on the side of the main beam of the cruciform, just to the right of the travelling lock, where the photos normally show two ground spikes. Does anyone know if there is a particular Mk, or national make, that has only one ground spike mounted on the side like that?
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#375
15-04-22, 01:16
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You should be able to upload pictures(select "manage attachments" in the additional options area below the text composition area). The most common problems seem to come from oversize images (both pixel count and file size can be trouble). See http://www.mapleleafup.net/forums/showthread.php?t=19 for some more guidance. If all else fails, another member may offer to wrangle the photos to fit.
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#377
15-04-22, 03:22
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Just been watching this interesting video from a Living History group in Malta, some nice original footage on display here.
https://www.facebook.com/watch/?v=191892833148902
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#378
15-04-22, 04:09
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Quote:
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#380
01-12-23, 11:21
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40mm Bofors photos
I hope you don`t mind me putting some of my original ww2 Bofors photos up from my
collection. Photo 1 British Bofors gun crew at Bettolle Italy summer 1944. Photo 2 AA Bofors gun and trucks Dunkirk 1940. Photo 3 AA Bofors gun Dunkirk 1940. Photo 4 AA Bofors gun Dunkirk 1940. Photo 5 AA Bofors gun Dunkirk 1940.
__________________
Keith
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#381
01-12-23, 13:15
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A few more from my collection.
Photos 1 to 3 Dunkirk 1940 Photo 4 Polish unit on trucks Photo 5 used as ground attack [ found on my PC ] i dont have the original. Press photo.
__________________
Keith
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#382
17-12-23, 20:36
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Quote:
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Linear Mode
