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rsuggitt

Bofors technical information ?

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The next work we need to do on our Bofors 40mm AA gun is to replace or re-temper the balance springs (which the USA call the equilibriator springs).  Problem is, we dont have any technical information about the springs.  Apart from the spring dimensions, we dont know the spring 'poundage' or 'spring rate' to get them retempered to.  All of the publications that I can find so far that mention the springs are for field servicing...  the springs might be replaced but they are not re-made, so the technical info is not included.  Anyone know of a source of technical / engineering info that would include the information we need ?

Many thanks

Richard

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3 hours ago, MatchFuzee said:

A possibility, the archives:- https://royalarmouries.org/collection/

Thanks for the suggestion, but unfortunately I've already tested that particular well and it's dry... they have the 1941 handbook (which we have a reprint of already) and it doesnt have the technical detail that we need.

 

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I would have thought the place to ask would be the royal artillery museum the archives is open to enquires by e-mail at royalartillerymuseum.com

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I wondered if there were any clues about the performance of the springs in EMER ARMAMENT B 528 although this is the Technical Handbook - Inspection Standard, it is only a Unit Inspection Standard & I can find nothing there to help you I'm afraid.

I don't have it, but more details of performance may be found in EMER ARMAMENT  A 521/33 Examination of Ordnance, Examination Data for Specific Equipments.

EMER Armament B 522 Technical Handbook - Technical  Description may have something or even in:

B 523 Unit Repairs

B 254 Part 1 Field Repairs

B 254 Part 2 Base Repairs

I have B 522-254, I'll try & find them & have a look.  I know nothing about armaments so could you explain where the springs are located & what they do, this will help me narrow down the areas I should be looking for.

 

 

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Have you tried any of these?

https://history.saab.com/en/archive/

I have only found images of the Bofors in the archive. There don't appear to be any contact details, perhaps Saab can help:- 

https://saab.com/

In 1999 the company Bofors Test Center, now owned by Saab Dynamics, BAE Systems and Eurenco Bofors, was formed:-

https://www.testcenter.se/about-us/history/

Weapon Systems Sweden (Bofors) is a part of BAE Systems’ Weapon Systems:-

https://www.baesystems.com/en/our-companies/our-businesses/platforms-and-services/locations/sweden

Have you taken the springs and/or explained what you require to a spring maker?.

If, you search "spring calculator" most of the sites that come have a  Spring Rate Formula.

 

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17 hours ago, fv1609 said:

I have B 522-254, I'll try & find them & have a look.  I know nothing about armaments so could you explain where the springs are located & what they do, this will help me narrow down the areas I should be looking for.

 

 

 

The springs are located in two cylinders that are positioned below the breech end of the barrel.  Rods come out of the back of the cylinders and are attached to the elevation quadrant.  They are pretty much in the centre of the following photo...

 

DSC00109.JPG

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Bit of coverage in the Technical Description. There is also some advice in Unit Repairs, I'll do those when the battery on my camera has charged up again.

Dsc01878.thumb.jpg.5d828d58aa774ce846111ab2b1049551.jpgDsc01872.thumb.jpg.e488d7a42acbaac698a97f641e6ab34a.jpg

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For info, "equilibrator" is apparently a valid British term too.  The FV433 Abbot has air over hydraulic equilibrator rams.

Andy

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many thanks again everyone... I didnt expect such a rapid and detailed reply.  I'm being dragged off to do 'normal' things for a day or so by SWMBO, but I'll look at all the contributions carefully as soon as I can.

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On 1/11/2019 at 12:16 AM, fv1609 said:

I wondered if there were any clues about the performance of the springs in EMER ARMAMENT B 528 although this is the Technical Handbook - Inspection Standard, it is only a Unit Inspection Standard & I can find nothing there to help you I'm afraid.

I don't have it, but more details of performance may be found in EMER ARMAMENT  A 521/33 Examination of Ordnance, Examination Data for Specific Equipments.

EMER Armament B 522 Technical Handbook - Technical  Description may have something or even in:

B 523 Unit Repairs

B 254 Part 1 Field Repairs

B 254 Part 2 Base Repairs

I have B 522-254, I'll try & find them & have a look.  I know nothing about armaments so could you explain where the springs are located & what they do, this will help me narrow down the areas I should be looking for.

 

 

Many thanks for this and your other posts.  One thing... I'm not familiar with the EMER ARMAMENT or these B numbers... can you give me some background please as to what it all refers to and where the documents can be found ? 

Also, I've been looking at the pictures you kindly posted... unfortunately these seem to be for a different gun as there are some significant differences from the gun we maintain.  We have the 40mm Bofors... is it possible the diagrams are for an earlier 25mm Bofors ?

Edited by rsuggitt

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There are large collections of EMERs on all subjects held by the REME Museum.

I'm not into guns so sorry I may have got the wrong weapon, what is the exact military nomenclature of the gun?

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On 1/11/2019 at 2:20 PM, MatchFuzee said:

Have you tried any of these?

..........

Have you taken the springs and/or explained what you require to a spring maker?.

 

 

I've not got very far with the SAAB references unfortunately... we have tried contacting BAe but that just goes into a black hole.  We've scheduled to take the springs out tomorrow (15 Jan) and thesewill go to a spring maker to repair or remake.

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7 minutes ago, fv1609 said:

There are large collections of EMERs on all subjects held by the REME Museum.

I'm not into guns so sorry I may have got the wrong weapon, what is the exact military nomenclature of the gun?

Thanks Clive... so far I've not thought of contacting the REME museum so that can be my next stop.  As far as I now, 'our' gun is a Bofors 40mm Anti-Aircraft gun, sometimes with the term L/60 or L/70 added (this refers to the length of the barrel).

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This is from the EMER ARMARMENT series B 520-529

So I don't know what you make of L2 & L3 in this instance? I think here L (meaning Land service) is the later incarnation of Mk.

Dsc01884.thumb.jpg.f6998a893590d1d7d1769ba1f2d871c4.jpg

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Clives literature covers the post war L70 series of guns. Your gun is the original Bofors L60 design. Even the early British built L60 is different to the original Swedish design, particularly in the carriage but also the ordnance, it being simplified for easier manufacture.

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1 hour ago, fv1609 said:

This is from the EMER ARMARMENT series B 520-529

So I don't know what you make of L2 & L3 in this instance? I think here L (meaning Land service) is the later incarnation of Mk.

 

Hello Clive,

I admit I've not encountered 'L' designations before, as you say it's probably an alternative to MK numbers   If it says anything about Balance springs at all I'll be happy to have that info (on the basis that anything is an advance on what we know at present).

 

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1 hour ago, Adrian Barrell said:

Clives literature covers the post war L70 series of guns. Your gun is the original Bofors L60 design. Even the early British built L60 is different to the original Swedish design, particularly in the carriage but also the ordnance, it being simplified for easier manufacture.

Hi Adrian,

That's noted thanks.... all I can hope is that the balance springs did not alter too much over time.

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2 hours ago, rsuggitt said:

If it says anything about Balance springs at all I'll be happy to have that info (on the basis that anything is an advance on what we know at present).

There are some references to springs in the pages I've posted that may have similarities of function to yours.

Thanks Adrian, as I said I know nothing about armaments :)

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