French 75's in action

[dominick]

From the video it appears that the front barrel lugs help guide the barrel while recoiling.  I have not found a definitive answer as to what their purpose is.  Here's a photo of a 75 with the barrel in the recoil position.  Maybe the front lugs supported the barrel while the cannon was transported?

[Cat Whisperer]

GOOD read!  THanks!

[Parrott-Cannon]

From the video it appears that the front barrel lugs help guide the barrel while recoiling.  I have not found a definitive answer as to what their purpose is.  Here's a photo of a 75 with the barrel in the recoil position.  Maybe the front lugs supported the barrel while the cannon was transported?

It appears to be a captured gun - German soldier in the front right of picture?

[Cannoneer]

Dom,
I’ve also been curious about the projections under the muzzle of the 75 since first seeing them, but so far I haven’t been able to come up with anything that fully describes their purpose. I don’t think they have anything to do with transporting the gun with the barrel held in the rearward recoil position (it doesn’t seem probable that the hydro-pneumatic recoil system would be kept under compression like that). There are photos that show the gun being towed with the barrel fully extended forward; and also there was a protective leather muzzle cover that completely enclosed the “roller side plates,” as they’re designated on a drawing in the  Handbook of Ordnance Data, United States Ordnance Dept. by Capt. Herbert Wade Treadwell, P. 41, Fig. 12.

http://commons.wikimedia.org/wiki/File:French_75_model_1897_barrel_cross-sections.jpeg


This is speculation on my part, but I think that the ‘side rollers’ were blocked by a plate on the slide that acted as a stop to the rearward travel of the barrel, so that the rod attached to the piston inside the cylinder didn’t have to endure that force.  If you look at the last “75” shown in the film, you can see the ‘side rollers’ going down the slide, and being entirely enclosed by the ‘jacket’ that covered the slides. 

http://www.militaryfactory.com/armor/imgs/canon-de-75-modele-1897_3.jpg 
U.S. troops transporting a "75" in WWI

[bilmac]

The name roller side plate would indicate to me that a roller went between them, there was a roller in the middle. The purpose of the roller is kind of a mystery, it doesn't appear to be installed. Maybe the guns were originally made with the structure under the bbl running all the way to the muzzle and that later it was discovered that this was just unnecessary weight and it was taken off.

Reminds me of how quickly combat innovation can be lost. In Viet Nam the big towed 155s were common on fire support bases, and they were regularly quickly shifted and shot at any direction of the compass. In the war I was light infantry and didn't pay much attention how they did that. A few years later I joined a National Guard red leg unit. No one in the unit knew how this had been done, and out of curiosity we were speculating and actually did some experimenting. What was commonly done in Nam was lost knowledge in just a few years.   

[Max Caliber]

I have never found a detailed description of how the lugs at the muzzle work, but since they only come into play when the barrel is at full recoil, their purpose must be to retard or stop the barrel from coming off the carriage if the recuperator looses air or oil pressure.

The picture of the 75 with the barrel in full recoil probably had a failed recuperator, maybe that was why it was captured. The barrel should not be in this position if the recuperator is working properly.

There are a number of French 75's around the US and a very nice one along with a limber, is located at the Harry Truman Library and Museum, in Independence. Missouri. Presented to the library by the French Government. Truman commanded a battery of  French 75's in WW1.