Barbette Cariage

[Zulu]

Can anyone explain the mechanics of a wooden barbette carriage to me.  Any picture I have seen shows a pair of big wheels that don't sit on anything.  Are these for turning by hand?  There must be secondary wheels inside of the big ones but I have'nt been able to find a picture.
Zulu

[seacoastartillery]

    Zulu,    go to the stickies above and pull up the GBO Sponsors, then click on Paulsen Brothers Ordnance, then go to All Metal Seacoast
Carriages, then click on the Front Pintle Barbette Carriage and then enlarge the lower left photo.  That one will show you how the large wheels and smaller, load bearing hub wheels work.  The artillerymen use handspikes in between the large wheel spokes to get the gun rolling.

FYI,

Tracy and Mike

     We just found these photos from one of our trips to the east coast and Georgia in particular.  We visited Fort McAlister, GA in 2006 and had a great time studying the fort and the artillery shell collection there.  A large portion of the original earthwork fort has been preserved and, despite the large number of mature trees which have grown up upon land which was cleared for artillery and musketry fire zones in the 1860s, you can still see the Ogeechee River over which the Federal Monitor ironclads once bowled their huge 15" shells into this riverside fort.

An excellent replica Front Pintle Barbette Carriage mounted in a strong position 25 feet above the river.




One tough Confederate Captain.




A beloved pet.




PS   While PBO Corp makes this carriage with long lasting steel and aluminum, the originals were indeed made of wooden timbers and iron fittings.

[Soot]

All the references I've found show the pintle in the center of that axle, but I don't understand what the wheels do since that don't seen to contact anything.
Anybody have a clue?

[GGaskill]

The big wheels riding outside of the wooden rails are used by the gun crew to return the gun to battery.  Their larger diameter and spokes give additional leverage (and keep fingers out of the way) to make the job easier.  They are connected to the small wheels that ride on the frame rails.

[seacoastartillery]

     With cannons, as with anything else, never assume anything.  What GGaskill said above is a very clear version of what I tried to say above when I assumed, wrongly, that everyone would understand, that since I described a handspike as being used in the spokes of the large wheels, that they would be connected to the smaller hub wheels which would then turn and move the upper carriage forward into battery.

     As for the other matter, the pintle pin, upon which the chassis, (lower carriage) rotates, it comes up out of it's anchor, (either a heavy timber platform or a very heavy, buried block of granite).  It enters a receiver hole in the forward transom of the chassis and may also protrude upward a bit into the front end of the center chassis rail which is flush with the front and the top of the transom.  It does Not go up through the wheel axle, being rather forward of this axle.  Be sure to look up the Paulsen Brothers Ordnance site, (link below). Their front and side pics and our rear pic should help you understand how this complex carriage works.

                                                               http://www.pbocorp.biz/

     Also, Mike and I have read that, with the tube dismounted, the upper carriage can be rolled for short distances, such as to a new position in the same fort or battery, on it's large wheels, but this does not mean that this mode of transport can be used over open country whether on roads or not.  

FYI,

Mike and Tracy

[Zulu]

Can someone explain how the leveling screw in this drawing works?  When you turn the handle the threaded rod must go up and down.  Is the handle fixed and goes up and down also?  I guess that can't be the case because it couldn't go down any further. 
I have seen pictures of the handle in a fixed position on the top of the threaded rod.  Then it is obvious how it works but I'm confused with this drawing.
Zulu

 

[Max Caliber]

Some artillery adjusting  mechanisms have the hand wheel fixed to the carriage and it does not move up or down, just the screw moves when the wheel is turned, one end of the screw being fixed to the barrel. Some large water valves also work this way, I think they are called traveling screws or something like that.

[seacoastartillery]

     The other type is shown in the Civil War era photo.  The handle is affixed to the elevating screw with a cross-pin at the top of the screw and the elevating screw plate is threaded to hold the screw in any position of tube elevation or depression.  Without tube preponderance, extra weight aft of the trunnions, neither type of elevating screw would work very well.

T&M

[Zulu]

Max Caliber,
For that to work the hand wheel would have to free turn in some type of housing that would be attached to the carriage.  Is that what you mean?  Do you think that is the case in the drawing?
Zulu

[Terry C.]

The elevator in the photo, with its hand wheel affixed to the screw, is probably a simplification of the original design, for ease of manufacture. In this case it would simply screw, as a unit, into a threaded socket in the transom.

The screw in the photo is free to raise and lower in it's socket, but not rotate. It would have either a slot in the screw for a pin to ride in, or a pin in the screw that fit in a corresponding slot in the carrige. Either way, rotating the threaded hand wheel would raise or lower the screw and set the elevation. The bottom of the hand wheel bears against the top of the unthreaded socket.

To me this is a superior design, as the hand wheel is always down out of harm's way. It would also be stronger and operate more smoothly, but it is more complex to make.

[Max Caliber]

Zulu, The hand wheel is held within a metal box like affair on the trail, free to turn and move a little from side to side. Here is a picture of a British gun carriage that uses a captive hand wheel but has an elevating screw that attaches to the barrel with a bolt. This type of mechanism was apparently used mostly on light and medium size artillery.

[Cannoneer]

I think that we borrowed this concept of elevation screw from our British cousins, (though they may have also done the same from another country) but we didn't attach the top of the screw to lugs on the underside of the barrel. As has already been said, it's the preponderance (greater weight at the breech) of the tube that allows this design to function. The threaded collar with handles remains seated on the base plate when rotated, and the male threaded screw raises and lowers without rotating. I would also venture a guess that the threads of the screw, the bottom of the collar, and the top of the plate were all kept well lubricated.

Drawing of a British elevation screw for a field carriage.


Elevation screw seen on a reproduction British block trail carriage on which an original British bronze light six-pounder is mounted.


U.S. wooden front pintle barbette carriage with the type of elevating screw where the female threaded collar remains seated on the base plate.

[Double D]

Here's the elevator on the 1844 8 inch mortar.







It consists of three part. The base, adjust wheel and threaded elevator

[Zulu]

You guys can come up with a picture of anything. Thanks!
If you haven't guessed by now, I am building a Barbette carriage.  In fact I just finished it yesterday and put the first coat of paint on it today.  It is 1/3 scale so it is pretty big.  It has been very challenging.  I had fun.  I am putting a 1/3 scale 100 pounder Parrott barrel on it.  I know Tracy and Mike wanted to see a seacoast 32 pounder but I opted for the Parrott.  Maybe I'll make a second barrel and interchange them every other week.  
Of coarse I'll post some pics when I finish painting and get it reassembled.
Zulu

[Terry C.]

Okay, DD's drawing shows the groove in the screw that I mentioned earlier.

Can't tell from the photo of the barbette carriage that Boom J posted whether that screw is slotted. If it is, the slot is turned away from the camera or otherwise hidden from view.

The other option that I mentioned is probably more likely. There could be a slot in the block underneath the handwheel for a crosspin in the lower end of the screw.

[edited to add: For a model, this would probably be the easiest method.)

Either way, the screw is held against rotation.  

In the illustrated field carriage elevator, none of this is necessary because the upper end of the screw is affixed to the breech of the gun.

[Zulu]

I ended up making this one out of threaded wood.  Thanks for the help.
Zulu

[Terry C.]

Did you make it like the photo, with the handwheel on top?

I'm curious to know the story behind the two different designs.

I'm still of the opinion that the change from the design in the original plans was done as a time/cost cutting measure during wartime production. But I'm open to other ideas.

[Double D]

Terry,

Grooved or slotted?

[Zulu]

Terry C,
The hand wheel is on top.  I did not want to have to secure the threaded rod to the barrel.  Plus, as you have stated, it was much easier and still original.
Zulu

[Zulu]

I am mounting a 1/3 scale Parrott barrel on my carriage but I suspect a 100 pounder was too heavy for a wooden barbette.  I have only seen them mounted on metal barbettes.  Any one have the answer to that?
A 100 pounder was 138" long and weighed 9727 lbs.  My barrel is 43" long so it is pretty close to 1/3 scale.  Whatever the case it sure looks good on the barbette.  A seacoast 32 pounder weighed 7200 lbs.
Zulu

[little seacoast]

Can't wait to see your pictures.  Now I've "finished" my field carriage, it would be so cool to have a barbette or Marsilly  carriage to interchange with.  A half scale 10 pounder Parrott probably isn't appropriate but I'll pretend it's a bigger one. Best Regards, LS

[Terry C.]

Terry,

Grooved or slotted?

The elevator with the handwheel on top goesn't need to be grooved or slotted. The whole thing turns together.

The groove or slot, whichever was used, would ne necessary for the original design (in the plans and in Boom J's photo) with the handwheel on bottom. The screw has to be held so that turning the threaded handwheel will raise or lower it.

Is that what you were asking?

[Double D]

Terry,

Basically yes...

[Terry C.]

This is why I believe that the design change was a result of wartime production. 

The screw with the handwheel on top requires fewer machining setps.

Of course this is all pure speculation on my part.

[Zulu]

Little Seacoast,
If you will look at the measurements, there is little difference between a 1/2 scale 10 pounder Parrott and a 1/3 scale 100 pounder Parrott.  It would look good on a 1/3 scale barbette.
Zulu

[Zulu]

Tracy and Mike,
Is a 100 pounder Parrott too heavy for a wooden barbette carraige?
I know you know the answer.
Zulu

[Zulu]

Well, here it is.  This was one of the most challenging carriages I have yet done.  It took a lot of study to just figure out how it went together.  It is a 1/3 scale 100 pounder Parrott rifle on a Barbette carriage.  My thanks to all who helped me out with answers to my questions.  It now resides in my foyer but there is no room to open the front door.  I will have to figure something else out.  The wheels are operable as is the threaded wood leveling screw.
Enjoy the pictures.
Zulu

[Zulu]

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[Soot]

That is way cool.
How about some pics of your entire collection all together.

[Zulu]

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