BANYAN

Screw Elevation Device for Guns

Hi again folks - sorry another research question.  The NMM search engine is hopeless (well for me anyway) :)

 

I am looking for  a good photo, drawing, illustration or even description of the screw elevating device used on guns in the mid-19th century.  The photo shows one of the guns fitted to HMCSS Victoria, but it is not sufficiently clear to determine how this device worked.  The screw part is clear, and from another photo it can be determined that it wet through the cascable (which has been flattened).  There is also a hint, on close inspection, of what may be a brass wingnut type handle at the base.  What is not clear is how this was fitted to the woodwork below, or what type of handle was fitted  (this would have been between the base and the cascable so as not to interfere with the sights etc.

 

post-385-0-55625600-1486790180.jpg

 

I have trawled through many pdf books of that period but have not been able to find anything. :(

 

Any help or pointers once again would be most appreciated.

 

cheers

 

Pat

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The spoked handle at the base is attached to and turns the threaded rod.  The cascabal is threaded, or has a threaded insert, and so rides up or down on the rod's threads, changing the elevation.

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Many thanks all, that is great.  

 

Thanks for that photo Dziadeczek; that shows it very clearly.

Jerry, based on the photo I have, I am not sure if she had the four spoked handle, but the principle would have been exactly that.

Thanasis, an interesting site, the first drawing gives a good idea of the principles.

 

Appreciate the feedback; helps me a lot with getting to grips with the gun.  Now, if I could just find an example of the same gun with this fitted :)

 

Pat

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Lavery says (The Arming and Fitting of English Ships of War 1600-1815):

 

The trunnions of carronades seem to have been replaced during or soon after the American War, by a loop placed under the gun.  The screw thread through the button, which allowed the gun to be elevated and depressed without the use of conventional quoins and wedges, appeared around the same time.

Though I have seen contemporary models and images showing these new stile carronades still using quoins after "the American War" (The American Revolution) especially on American guns.  We too adopted the elevation screw in time.
 
The quoin wasn't fully replaced.  Many "modern" guns in the American Civil War used quoins that sat on a toothed track and fine elevation was done with a screw that moved it fore-and-aft.

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Thanks again Jerry,  I am confident that these were the style of gun we had as that photo is the actual ship with her canon (taken c1865) - just not clear enough for much detail :(

 

One issue has arisen that I am still trying to resolve.  How was the base of the screw fitted to the rear chock (which replaced the after trucks as shown in the photo)?  If the bottom of the screw was fixed to a plate, how then did the gun ride up and down as the vertical angle would have changed quite a bit when depressed or elevated this snapping it, or jamming the thread?  I am assuming the end was ball shaped and sat in some sort of hollowed spherical joint to allow it to change the vertical angle of the screw as required; I think a swivel joint would have been too weak?  The weight of the gun alone would have kept the ball in its socket/in situ I think.

 

cheers

 

Pat

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Pat, your above comments about the bending moment caused by a fixed screw rotated around the trunnions is music to my ears, something was done to relieve that tension or the soft iron screw will bend or the cascable will be broken. Suspect the early screw elevation devices used hand jacking to bring the gun to the desired elevation and then the screw was turned into place and the hand jacks removed, a turn or two could fine tune the elevation without creating much of a bending moment in the screw. Suspect that some guns were equipped with pined nuts at the breach, in the cascable, so as the elevation was changed the nut could pivot, if the screw was secured or set into a socket that allowed rotation and rotation ahead and rearward the screw with a pined nut in place could bear the weight the whole time it was being turned to bring the gun to the proper elevation without harm or binding. I have yet to see a setup I would want for a gun of mine, probably a case of self proclaimed and unquestioned experts setting up the displays we see today. Details about elevating screws and their fittings are important to those who understand a bit of physics and want to see usable provisions to meet the demands of reality, not so much to most who look past the fine details. Hope you are able to root out some usable info and post it for us.

jud :pirate41:

 

Sometime we do some fixes normally not found in official publications.  This was published in an in country newspaper for the armed forces.post-5330-0-04466000-1486872477_thumb.jpg

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Thanks Jud; interesting observation about the hand jack and it seems to be jogging something I have read (but that may have been for a pivot gun in this era). The pinned nut sounds a very sound solution, but the I know the particular gun we had on this ship had a screw through the cascable which appears to have been tapped through the metal directly look at the photos I have. As you say, "self proclaimed and unquestioned experts setting up the displays we see today" is so very true - have a look what they did to this gun which has a strong possibility of having been on the HMCSS Victoria.  The screw itself may be original (not verified) but the handle, and the base plate certainly are not.  the handle in such a position would have interfered with the Tangent Sight.

 

post-385-0-57488600-1486887566_thumb.jpg

 

I will be certain to post anything else i find.  It has been an interesting hunt for relevant info during this period and I am very surprised to find there is not more readily available.  A couple of contemporary texts written by Simpson for the USN, and General Howard Douglas (British) have proven the most useful sources of information to date.

 

love that zip gun solution - necessity is the driver of invention in so many circumstances.

 

cheers

 

Pat

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Nice photo, you are right about something wrong with the elevation control and adjustment for that gun. If nothing else, not enough available movement in that arrangement to allow the gun to be fired in an arc at a distant target. Sight interference could have been worked out but probably a consideration for the arrangement where the turning handles or wheels in some photos are below the cascable.

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Philip Broke of the Shannon was a great proponent of the carronade and spent a lot of time on devising better ways of mounting and using them.  His writings were the subject of an article by Martin Bibbings in the Mariner’s Mirror last year (vol.103, no 3, 2016).  The article includes a quote from one of Broke’s reports that, in passing, provides a contemporary view of the use of the elevating screw.  As part of a discussion about the position of the mounting loop for the carronade, the article reads:

 

“ With the loop no longer close to the centre line of bore but underneath, this imparted a rotating movement when the gun was fired accentuating the already violent recoil and putting excessive pressure on the breech and the delicate elevating screw mechanism:

On the discharge of a gun, the unsteadiness of the recoil and the jump of the piece by the striking of the breech on the quoin or on the elevating screw, are greatly affected by what is called the preponderance, an element which depends much on the position of the trunnions ... the muzzle droops on firing, and violent shocks are produced on the quoin or screw; and these effects are much aggravated when the common axis of the trunnions is below that of the bore” (H D Douglas, Treatise on Naval Gunnery, 1820)

“ The screw mechanism with which carronades were equipped took the place of the manual method of adjustment using wooden hand crows to elevate the barrel on conventional cannon. The wedge shaped quoin was still employed however, inserted under the breech after the elevating screw had achieved the desired elevation.  Failure to insert the quoin could result in the screw thread being fractured when the piece was fired, or as Broke put it: 'the carronade being ruined by the neglect of the carpenter'.” (The National Archives, WO 55/1832).

“ The imperfect balance of the carronade on its trunnion loop in recoil was reversed when the gun was moving forward:

“ until the breeching screws now in use were supplied with a lock nut to prevent ' the breech from rising up — the Carronades frequently threw away their shot by dipping their muzzles with the roll of the ship or with the shock of running them out . . . this fault is remedied by confining the lower end of the screw to the carriage, but the depression of the Gun is thereby so much limited, that ... when lying over with the pressure of stiff breeze the carronade could not be depressed sufficiently to strike an Enemy ship . . . even in close action — so that the battery when fighting a ship to windward ... would be totally efficient unless the screws were released from their confinement . . . and a quoin placed under them.”(Philip Broke to the Ordnance Board, 1810)

 

The above extract and contemporary quotations bear on questions raised in the earlier replies.  In particular, they show that the use of the quoin was retained, although after the elevation had been set rather than before.  In practice, I suspect that the technique was to hammer in the quoin to get roughly the right elevation, loosen it to make small adjustments with the screw and then (with luck!) replace it again before firing.

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Thanks John, makes you wonder if the elevating screw really was an improvement to the aiming of the gun :)?

 

Jud, someone in their infinite wisdom decided to "remodel" the screw (probably one of those well intentioned ... mentioned above) so the four prong handle at the top and the fixing plate at the base of the screw are completely alien to the gun.  Comparing this arrangement to the photo (of the Victoria) the original Victoria arrangement of her 32pdr 25cwt gun had a handle at the base (similar arrangement to Constitution carronade) but a slightly different handle design I think.  as you point out, the modified bottom plate would simply not have worked in that arrangement.

 

cheers

 

Pat

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Hi again all.  While again a carronade and not a 32pdr gun this drawing shows the base of the screw having a bulbous end that fitted into a hollowed trough in the timber.  This arrangement would have allowed it to slidealong along longitudinally and aligned with the axis of the bore while staying perpendicular to the thread cut in the cascable.  The other photo is of a carronade fitted to HMS Trincomalee (Leda Class) which shows what looks like a ball and socket style joint.   Both of these are contemporary I think, so unless I can find something else a little closer to 1855, I don't know which is the better way to go?

 

post-385-0-34698200-1486950498.gif   post-385-0-43296200-1486950674.jpg

 

cheers

 

Pat

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Keeping the trough well greased would allow enough movement as the screw was rotated to relieve the bending moment from the change of angle as the gun rotated around the trunion. A solution that would work if the breach did not jump after each shot, perhaps a hold down clip along the trough would be useful to not stop but to limit the motion and resulting pounding.

jud

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Thanks for the feedback again Jud.  I agree, the breech would be very prone to jump with firing;  I wonder if the option of the quoin; as cited in John's post (from mariner's Mirror); helped dampen this effect.  The older guns with quoin would have had the same issue (hadn't thought of it before now) as nothing restrained it from vertical movement (except the weight of the gun). That said, I think the issue was exacerbated with the lower positioning of the trunnions on which the additional pivoting moment may have been the real problem.

 

I am going to have a trawl through the MM to see what additional info (if any) I can find.

 

At least with Victoria, having the standard gun with standard trunnion positioning, the elevation and jumping issues will not have been as bad.

 

cheers

 

Pat

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I'd go with what you have, Pat.   During the American Not-so-Civil War, there were some rather large cannon that used the screw and wheel but they were on a carriage with lugs on the side of the cannon resembles what you have in the first picture....  I don't remember seeing any quoins used with the American guns so maybe there's something to the lugs on side negating the need for the quoin????   Or am I missing something here?

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Thanks for the feedback again Jud.  I agree, the breech would be very prone to jump with firing;  I wonder if the option of the quoin; as cited in John's post (from mariner's Mirror); helped dampen this effect.  The older guns with quoin would have had the same issue (hadn't thought of it before now) as nothing restrained it from vertical movement (except the weight of the gun). That said, I think the issue was exacerbated with the lower positioning of the trunnions on which the additional pivoting moment may have been the real problem.

 

I am going to have a trawl through the MM to see what additional info (if any) I can find.

 

At least with Victoria, having the standard gun with standard trunnion positioning, the elevation and jumping issues will not have been as bad.

 

cheers

 

Pat

Pat,

 

If you haven't lost the will to live by now, there's a lot more material about stabilizing the carronade in the MM article that I quoted.

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Pat,

 

When you look at the top of the screw part, you can see a distinct black dot, which is probably a hole for a rod. A single rod would suffice to twist it around ..., being able to remove it, it wouldn't hinder the sighting over much. looking at the coarsness of the thread, I would say it travels relatively quick up and down

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Thanks for the additional feedback Mark, Carl and John; much appreciated.

 

John, any information would be very useful.  I tried looking at the MM site but you need to be a member to get that article unfortunately. 

 

Mark, I will be using something very similar.  See my photo following re the Quoin which I think was fitted - there is something that looks like the top of a coin under the base ring?

 

Carl, Looking closer at this enhanced close-up of that photo, it looks remarkably similar to the one drawn for the carronade and what I thought were handles are not; it looks more like that bulbous end.  Also, could you point out that black hole on the photo for me please; I am not sure where specifically you mean?

 

post-385-0-51314400-1486999401_thumb.jpg

 

For all; I cannot fathom what that black spike thing at the rear of the bracket almost horizontally in-line with the screw is either - any ideas?  One possible option is that it is a handle/rod that is not very well in focus?

 

cheers

 

Pat

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The elevating screw must not have been that much of a problem since it survives well beyond the Civil War

 

This from The Gunnery Catechism as Applied to Naval Ordnance 1865.  Notice Part I, the "saucer" for the elevation screw to set into.

 

post-961-0-93251500-1487008333.jpg

 

post-961-0-22468600-1487008334.jpg

 

post-961-0-50043600-1487008334.jpg

 

BTW: On field pieces the elevation screw is reversed, that is it threads into the carriage and the heel of the breech rests on it.  It's raised off the ground on 5 foot wheels, so there's space under it for the screw to stick out, which is not an option for a naval piece.

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That is a trough in  my feeble vocabulary, but you and the sketch are welcome to refer to it as a saucer, kept greased so as the screw was rotated the lower end of the screw riding in it would move and relieve the bending moment caused by the rigid screw rotating around the trunnions, which in this sketch are at the C/L of the 9" rifled bore. The earlier carronades unlike the cannonades rotated around a rigid pin through a loop cast into the gun far below the bore. It is the modeling and displays of such guns that close inspection reveal that, as depicted, keeping guns in action as so depicted would be a problem. The guns were used, the screw devices were used, historical fact as is the fact that the laws of Psychics must be obeyed, the only assumption that can be made as we see in the displays to date on this site is that something is missing in the attempts to show actual practice. Rifled guns and better steels put a short life for heavy cast muzzle loaders and as alloys improved, breach loaders became lighter forcing screw elevation gear to quickly became an interesting footnote in history. Attempting to use the 1865 screw elevation technology with 1820 carronades would result in something like putting a Knuckle Head Engine on a 2 wheel high ride bicycle, get the thrill of the first bit of motion, then the crash. The search here is for reality, not denial that screws were used, only how.

jud :pirate41:

 

Interesting, ' Sweep Piece', have been wondering where they were in all the drawings and models I have seen. When I asked, the response was a bit insulting for me to wonder how preventable  damage to the ships inner hull would have been important enough to take steps to prevent it. I expect that steps were always taken to keep the gun, it's carriage and wheels away from the inner bulwarks. Little off subject complaining over with, I feel better now.

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Thanks for the continued feedback and interesting discussion guys.

 

Jerry, that is an interesting drawing.  I had seen a similar one but not with as much detail, and that helps a lot.  Victoria (1855) is closer in period date to this gun than earlier Carronades, but I think will still have had much in common. 

 

Jud, agree (on both points) - still trying to ascertain how the screw was rotated, and exactly what style of trough or joint was utilised; I am leaning to trough rather than joint though.  Victoria appears to have had very light bulwarks compared to the drawing, photos etc of contemporary vessels, so the employment of a sweep piece (or bumper - I know just using their words :)) would have been essential - but is not evident in the photo due to the angle it is taken and the gun being run-out.

 

I am learning a lot from this discussion which is proving beneficial to the build, and for my personal understanding.

 

Another interesting tid-bit I found, and not mentioned much, is that some Quoins were marked  to allow quicker adjustment of the elevation - see illustration from “Naval Gunnery – A Description and History of the Fighting Equipment of a Man-of-War” by Captain H Garbett, R.N. published by George Bell and Sons in London 1897.  Page 26

 

Thanks again

 

Pat

post-385-0-02766300-1487029045.jpg

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The elevating screw must not have been that much of a problem since it survives well beyond the Civil War

 

 

I'm not sure how generally true that is.  I've just been looking over my photos of HMS Warrior (1860), which at the time was the last word in Royal Navy architecture.  The main gun deck was fitted with 64pdr muzzle loaders and 110pdr breech loaders, and neither used elevating screws.  They all depended on quoins.

 

It rather suggests that the screws had dropped out of favour, at least on this side of the pond, and that can only be because of their relatively fragile nature - as pointed out by several contributors.

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Hi folks another update.  

 

I contacted the HMS Trincomalee National Museum (Royal Navy), and the Curator has kindly helped me in providing two good photos of the screw elevating mechanism as fitted to their carronades.

 

I have their permission to use the following photos.  i think this is the design I will go with as there are a lot of similarities with it that can just be made out in the B&W detail photo of Victoria's gun.  This design allowed the base of the screw to move around on the ball end  over the plate in any direction.  Thanks all for the input.

 

post-385-0-80211200-1487213720_thumb.jpg   post-385-0-77051300-1487213740_thumb.jpg

 

cheers

 

Pat

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