Landships II

I have wondered the same thing. I am in the early stages of building a detailed 1:8 scale model of the French 75 (as I posted on this forum a few months ago.)

While my model will be as functional as I can make it. But it is not intended to be a firing cannon. Therefore, my model need not punch out an empty shell casing.
I've studied French and American drawings and visited two actual guns: a M1897A3 at Camp Roberts in April, and an actual French 1897 last month at the Orange County Court House, both in California.

The one at Camp Roberts is at a museum. Although outdoors, it is in fairly good shape. Because my project is on the original French version, the M1897A3 carriage, with its dual trail, steel wheels/rubber tires, etc was rather a disappointment after a six hour drive, not really relevant to my project. But its breech was operable. It had no firing pin, but I could operate the safety and open/close the breech, seeing the extractor arms.

The French one is in 24x7 open public display as a war memorial. As expected, its working mechanisms are immobilized. In this case, the breech is tack-welded closed. The main focus of my July visit was to study and measure the wheels and axle components, as that is the focus of my current machining and woodworking. It's just 80 miles from here, so I will be returning there for further observations. Other than the welds, some things are missing (notably the shield and sighting mechanisms.)

It doesn't show well in your image, but the extractor spindle in your diagram is an oddly curved piece. I have a French diagram that labels it "Poignée de l'axe d'extracteur", or extractor axis handle. When the breech is fully opened, I believe it depresses this handle enabling the extractor to push the shell out. But I don't see anything that would forcibly expel the shell. It seems more like some shotguns, where when you break it open, the spent shell is just lifted a little bit clear of the breech enabling you to easily grasp the brass for removal. But I have see online video of the French 75 in rapid fire action. When that breech is opened, the shell is forcibly ejected, not just lifted clear.
I don't see any spring that gets cocked to store enough energy to do this. Nor do I yet see any connection between the recoil brake and the ejector where somehow energy is absorbed during the recoil, stored while the barrel is returning to battery, then released to the ejector when the breech is opened.
Related to this, I don't understand the function and operation of that rectangular latch key on the underside of the barrel.

Greg

The motion of the breech block moving back triggers the extractor.  The motion back is only by hand. 

Hope this helps

R/

Ralph

 

 

 

From the Mle 1897 manual:

"23. Fonctionnement de  l'extracteur.  —   La  culasse étant

fermée, les branches de l’extracteur sont appliquées contre

le tube par le bourrelet de la douille.

Pendant  l'ouverture de  la culasse, la rainure du talon

d'extracteur défile devant le talon et,à la fin du mouvement,

la rampe d’éjection  vient heurter la rampé hélicoïdale du

talon;  ce choc entraîne   le   mouvement  vers l'arrière de

branches de  l'extracteur,  ce qui produit le décollement et

l'éjection de la douille.

Lors du chargement, le Lancement de la cartouche dans

l'âme provoque le basculement vers l’avant des branches de

l'extracteur et, par suite de la réaction du talon sur la rampe

d'éjection, un commencement de fermeture de la culasse."

Google translates this as:

"23. Operation of the extractor. - The cylinder head being

closed, the arms of the extractor are applied against

the tube by the bead of the sleeve.

During the opening of the breech, the heel groove

stripper moves past the heel and at the end of the movement,

the ejection ramp strikes the worm crawled from

heel; This shock causes the backward movement of

branches of the extractor, resulting in delamination and

ejection of the sleeve (cartridge).

When charging, the launch of the cartridge in

the core causes the forward tilting of the branches of

and the extractor as a result of the reaction of the heel on the ramp

Eject a breech closure beginning."

If you look at the diagrams (lithographs) of the breech block of the Mle 1897 there are machined ramps on the inside of the block which are designated as

extractor ramps. These engage the tenon attached the extractor axle as the breech is turned. The extractor arms are forced rearwards and pull the cartridge

out of the breech. It's a fairly simple system and reminds me somewhat of the Nordenfeld breech on the earlier 6 Pounder anti-torpedo boat gun.  

Regards,

Charlie

 

Thanks everyone for your input. I rewatched, in a frame-by-frame mode, those videos mentioned above. In one frame, the hammer falls on the firing pin, in the next frame it is at full recoil. Return to battery takes a few frames. While it's still moving, the soldier on the right already has grabbed the handle, opened the breech, and the shell is ejected. Then, about 6 more inches of travel and finally it is at battery. (What is that soldier's role on the gun team actually called?)

It seems that we are thinking that the actual ejection is powered purely by that man's rotating the breech to the open position, at which point, the edge of the manivelle (crank) arm pushes down on the poignée de l'axe d'extracteur, aka Extractor Spindle (perhaps via the goupille de loquet (latch pin)? (See Plance IV in those French drawings.)  This motion then moves the extractor arm rearwards, ejecting the shell.  It doesn't seem there is enough leverage in this process to so forcibly expel the shell. But clearly, this is the mechanism that actually does the ejector, not merely tripping a trigger that releases any stored energy (e.g. spring/hydraulic/pneaumatic). I wish I could ask my grandfather (whose gun battery fired the first American shot of WW I.)

Here are a two of my photos of the M1897A3 at the Camp Roberts Museum, San Miguel, California. Unfortunately, ejector parts are missing, the left side shot fails to show the poignée de l'axe d'extracteur, aka Extractor Spindle. And the clavette is replaced by a rotten chunk of wood. And the breech open image shows the slots where the ejector axle, arms, and tang are located. I operated the breech open and closed a few times, but not while seated nor while the barrel was moving! 

And from the Model 1897 at the Old Orange County Courthouse, Santa Ana, California,  the left side view wheel image does show the curved Extractor Spindle arm (when you zoom in.)

Anyone want more photos? Any specific details or measurements for my next visit to Orange County?

Meanwhile, after lunch, I'm back to my workshop to work on my 1:8 scale M1897. Today, hopefully finish cutting the 14 jantes (fellows) for the wooden wheels (Planche XXIV in the French drawings), and machining the width of their cercles (tires or rims). These tires are from 14 gauge steel, I haven't yet figured exactly how I will bend and weld them.  Probably will make a plain wooden disk to guide the bending of red hot strips, and a special fixture to clamp the ends together while I weld them.  I haven't yet started making the spokes and the spoke shoes will be difficult to make in an efficient manner, I need 28 of them. 

Greg

Thanks Greg for the revealing picture of the breech. I had been looking at a lot of photos, but never got to see the inner ramps on the breech block's front side.

I am sure more gaps in my reference image gallery will occur while creating my 3d model. The most critical parts are the button side of the chassis and the mechanics that control the elevation of the gun's barrel, located between barrel and chassis.

There is no real-life example near to where I live, so any detailed images you can upload would make me happy.

Apart from that good luck with your research!

These are technical drawings of the French 75mm mle/97 breech ring and breech.  Hopefully, this will be helpful with your project.

R/

Ralph