Cuvelage pour cloche GFM PM2 et PMA

Hello Michal

Sorry for the late answer to your discussion thread. This is quite interesting as this forms, if confirmed, a clear deviation from CORF standards, as designed in 1930* and described in the GFM-A page.

In fact I did'nt find any trace in the documentation of such a deviation (ie. using LG type reinforced cuvelages for GFM A cloches in the Alps). There are even evidences that at least the orders and purchase for one of your exception was quite conventional (see below attached document).

Reinforced cuvelages in cast iron for GFM do exist : but they were 1000 mm high (neither 600, nor 1200) and limited in use to GM cloches.

A few comments, starting from there :
- all the cloches that you are referring to are installed in MOM built ouvrages (except Plan-Caval), lately equiped (as far as I know, their equipment has been done way after CORF and ITTF dissolution). This could explain deviations from standards as the guardians of the temple were no longer there to forbid this kind of oddities...
- I didn't check one by one for all, but it is possible that each of these cloches were equiped with at least one special créneau. In a context of low concrete protection blocks, it is sensible to consider putting a reinforced cuvelage as the cloche is strongly emerging from the concrete slab and needing protection underneath, protection only lightly provided by a lengthened virole in welded 30mm steel sheets. This is at least the logic behind the development of the reinforced cuvelage for GM cloches.

Well... these are all hypotheses, which need to be confirmed by historical evidences. These evidences are lacking so far, but if they exist it is only a matter of time to find them. I have to admit on my side that I didn't spend much time so far on technical specificities of "CORF petits ouvrages built by MOM" in the Alps.

Best regards
Jean-Michel

* a very comprehensive "Notice on cloche GFM" has been written late 1930 and sent to the Alps military engineering directions.

Hello Jean-Michel

Thanks for your answer. But bloc B 3 La Béole has a cuvelage 600 mm, not allongé 1200 mm. For some dimensions of the cloches PM2 and PMA in the Alps see you to my chart below.

Is it known any photo from inside of the PM2 or PM1 cloche with some screws or rivet between iron-plate cuvelage and its upper or lower reinforcement (rolled L)? Because I didn't see no trace of this connection in the Alps.


Best regards
Michal

Dernière modification par jolasjm le 29/09/2022.
hello Michal

I'll take some time to investigate your documents (I'm going on travel for now). With respect to your question on pictures of iron plate cuvelage, I did a very quick search. Please see below (taken at Lavoir-EM).

I'll have a deeper look when back.

Best regards
Jean-Michel

Hello Jean-Michel

It's a very good finding. Yes, I agree that there is visible connection between barrel and reinforcements. And that these rivets are significant for official design. I'll try to find photos from another ouvrages in the Alps.

Best regards
Michal

Hello Michal

Please bear in mind that the setting of these mechanically bound viroles could also be supplier dependent. I’m in fact wondering if some suppliers would not have chosen to screw things from outside or use sunk screws which are no longer visible behind the paint.

For sure, this discussion will push me to look at these viroles with a different eye ;-)

Best regards.
Jean-Michel