Parrott question, trunion caps

[Soot]

Hi, I've been searching for info on this for quite some time but I've never seen it addressed anywhere. It looks to me like larger Parrott rifles and some others don't have any type of trunnion caps. The smaller field models like the 10pdr do. Is it just gravity and the angle of the carriage that keeps the barrel in place or am I missing something? Thanks.

[Double D]

This 15 inch Rodman doesn't appear to have caps



This 8 inch Rodman has a spacer to make the trunnion fit, but no caps.



This 8  inch siege Mortar has caps



So does this 13 inch.



 

[Soot]

Exactly, even big mortars have caps, why not these guns? I could see 10,000+ pounds of barrel holding it self down, I guess. But what about the quite small in comparison, SeaCoast Artillery replica? It looks to me like the angle of the carriage and gravity hold it all together, weird.

[Cat Whisperer]

Soot -

WELCOME to the board!

Good question!  I don't have an answer, but good question!

DD -

That one "spacer" on the Rodman looked like a CAM!

[Terry C.]

It could be due to the recoil-absorbing nature of the barbette mounts of the Rodmans and large Parrotts.

[seacoastartillery]

     You guys are sharp!  Parts of the reason have already been revealed, but in addition to the much increased weight of these tubes and the way they are allowed to move, with their upper carriages to the rear during recoil upon the smooth surfaces of the chassis rails which are inclined from 3 deg to 7 deg., there is also a very subtle engineering design factor at work here.  By design, the rear of the trunnion cradle is just slightly higher that the front which is in the same plane, in which lies the trunnion axis. So movement is stopped by a mechanical feature, not just weight.  Field guns and mortars jump all over and sometimes rebound violently, hence the Capsquares used to retain the trunnions. 
     Naval cannon, even very heavy ones, use Capsquares as well due to the lurching of their carriages upon the deck while underway. 

Regards,

Tracy and Mike

[Soot]

Genius Civil War engineering, cool.

[GGaskill]

Another thing to consider is that field artillery spends most of its time being transported on rough roads (no interstates in their days) and the tubes needed to be restrained from bouncing out of the carriages.  The seacoast artillery didn't move once emplaced.  Also, the guns are fired with some elevation so the recoil has a downward component that helps hold the trunnions in the carriages.

[phalanx]

The trunnion cap, and cradles i have ,or the ones i have seen for wooden carriages that people bought separate for a project ,came as a set.
Like buying a bearing ,A perfect match between cap and cradle.
The rear of them is cantered up from the front about 30 degrees ,Allowing the recoil of the Barrel when fired to be pushing back on the bearing surface and not where the two parts join ,or the joining bolt.
I often wondered about this myself ,after seeing photos of guns with no caps.
In that one photo that DD put up the entire cap and cradle are cantered buy the carriage angle.

[Soot]

Thanks for all the replys, this is all very interesting.
This is also interesting. I didn't see anywhere else to post it so I'll put it here.
This is a link to the 12in seacoast rifled mortars by my house, with lots of good tech data.
http://www.fortdesoto.com/

[Terry C.]

Those 12" mortars have appeared here before.

I can't remember who posted them, but they deserve a second look.

[seacoastartillery]

     Double D posted a very interesting thread a while back which had some very nice pics of those deck-crushing, 12 ", Model 1890 Mortars.  I hope this link gets you there:

http://www.gboreloaded.com/forums/index.php/topic,126704.0.html


Regards,  Mike and Tracy

[Terry C.]

Okay, I was wrong. The 12" mortars in the photos that I remembered were the ones on Corregidor.

But there was mention of the battery at Ft. DeSoto, so maybe that stuck in my head.