rsuggitt

Thanks, I'll give ROF Heritage a try.

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

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).

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).

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.

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 ?

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.

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...

Those are some great ideas everyone, many thanks for contributing. I'll get busy with them over the next few days. :)

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.

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

Just to catch up... we got hold of the 1941 manual which had just enough information in it that we now understand how this corrector is used (and why it turns when the gun is traversed) .

Many thanks for those scans ! As it happens I'm just about to go off on vacation, I'll take a close look once I'm back.

Many thanks, a page or two woul help confirm we're looking in the right place. I dont think that the sight system was used in any other guns though.

Many thanks for that... I've not encountered that document/manual before. Might it also cover the operation of the 'Bofors Speed and Course Sight ' or 'Bofors Corrector Sight' ?