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Armor/AFV: AA/AT/Artillery
For discussions about artillery and anti-aircraft or anti-tank guns.
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Q: Purpose of Tabs on 6 pdr Rims?
SdAufKla
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Posted: Saturday, January 03, 2015 - 07:59 PM UTC
Hi all,

Doing some research on the British Ordnance Quick-Firing 6 pdr Antitank Gun for an up-coming build.

I'm trying to find out the purpose for these T-shaped tabs that are welded around the outside edge of the rims:



I've also seen similar tabs on the rims of 25 pdr's, so I'm assuming that they were a standard fitting with a pretty well understood purpose. However, nothing in my personal library has any info, and I guess that my "Google-foo is much weak" since after hours of looking, I can't find anything online either.

After studying the darned things (do they even have an official designation?), I can only guess as to their purpose. I THINK they may be designed to provide extra leverage to rotate the wheels when using the man-handling ropes hooked to the wheel hubs. If the rope was hooked to the hub and then passed around one of the tabs near the top or bottom dead center and pulled, it might help rotate the wheel moving the gun into and out of firing positions.

This is just a guess, though, and I can imagine some other purpose could have been intended.

So, the question is:

Does anyone here know? Is there some reference that you can recommend that might have the answer?

These tabs are missing from the rims on the Riich Models kit, and the gun that I'm building had them, so I want to be able to identify the parts and their purpose in my build notes.

TIA and Happy Modeling!
KurtLaughlin
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Posted: Saturday, January 03, 2015 - 10:40 PM UTC

Quoted Text

. . . I THINK they may be designed to provide extra leverage to rotate the wheels when using the man-handling ropes hooked to the wheel hubs. If the rope was hooked to the hub and then passed around one of the tabs near the top or bottom dead center and pulled, it might help rotate the wheel moving the gun into and out of firing positions.



That seems plausible, except that rather than ropes, I would say that a steel bar or handspike inserted into the harness loop on the hub would fit into the notches of the lugs for extra purchase.

KL

DKeu8726
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Posted: Saturday, January 03, 2015 - 11:27 PM UTC
Hi
I found this to books at Osprey.

British Anti-tank artillery 1939-1945

US anti-tank Artillery 1941- 1945

Maybe they have a answer to your question.
SdAufKla
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Posted: Sunday, January 04, 2015 - 03:12 AM UTC
@ Sune: Thanks for the book suggestions.

@ Kurt: I appreciate the thoughts and observations.

I'm usually not quite so baffled by these kinds of things. With some thought and / or a bit of research, most of these sorts of "mystery" gadgets can be figured out fairly easily.

However, with these rim-tab things, I can't clearly visualize their function or how they were used.

Some more information:

The OQF 6pdr ATG had two to four hauling ropes that were stowed on the front of the shield above the gun barrel. Each of these ropes was fairly thick (from photos, I'd estimate a little larger than an inch in diameter). They had metal eyelets with hooks spliced on the ends, and period photos show them hooked into the hauling eyelets on the wheel hubs with the gun crew manhandling the piece into or out of position or hooking it up to its prime mover, etc.

The gun also had two, tubular metal levers that were fitted into short lengths of pipe on the ends of the trails. These were carried on the sides of one of the trails and also used by the crew to maneuver the piece. The mounting pipes were equipped with pins and keeper chains to fasten these levers in place when in use to move the gun (although photos of the levers in use are pretty scarce).

These levers are quite a bit too large in diameter to fit into the hauling eyelets on the hubs. Their diameter is also considerably larger than the radius of the notches on either side of the tabs on the rims, suggesting to me that they were not intended to be fitted together.

As far as I can determine, there were no other tools issued with the gun that could be used as levers, and even the two "handspikes" for the trails are not designed with the arty traditional wedged ends.

Here are a coupe more photos of OQF 6pdr ATG wheels showing the rims and tabs from different angles to help visualize their geometry.





In this second photo, you can see that the sidewall bulge of the tires would interfere with using a straight lever across the wheel from one tab to another (offsetting to one side of the hub). Obviously, the hub would prevent using a lever across the wheel to tabs directly opposite each other.

It might have been possible to use the pulley / sheave-like area on the hub as a fulcrum with the end of a lever notched on the side of one of the tabs. However, I think the pulley-sheave is almost in the same plane as the notches on the sides of the tabs, which probably means that this is not possible because of the same tire sidewall issue described above.

Here are two more photos of SIMILAR tabs on, respectively, the rims of the OQF 17pdr ATG and the Ord 25pdr HOW.





In the first photo (the 17pdr wheel) you can see that the design of the tabs is hook-like and not T-shaped with the opening of the hook towards the center of the wheel. There are also only 5 tabs on these wheels (vice 6 on the 6pdr).

The different shape, in particular, suggests that the way these tabs were used was somewhat different than on the 6pdr but the purpose was presumably the same.

The wheel hubs on these guns also don't have the pulley-sheave like fixture found on the 6pdr wheels. (If that makes any difference, except to suggest that the pulley-sheave wasn't intended for use with the rim-tabs?)

I really thought that some arty buff would have had the answer to this question almost immediately and that after reading it, I'd have had one of those Homer Simpson "Duh!" moments by now.

Hopefully, someone out there has a copy of the manual with the gun crew drill explained and illustrated and can look up the answer to this little puzzle.

Happy Modeling!
Hohenstaufen
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Posted: Sunday, January 04, 2015 - 05:55 PM UTC
I've got the Osprey title that is specific to the 25 Pounder, and there are several pictures which show these tabs, but neither the text nor the photo captions refer to them ! There is a very clear photo of the drag ropes in use in mud in the Far East, but I can't see how the tabs would help in this instance anyway. They have the look as though something is intended to be attached to them, like a hub cap, or chains, or some other form of attachment for poor conditions, but there is no photographic support for this. Then I wondered if it was something to do with the fact they are split rims, and they were for a tyre lever or something, but the Quad, which is also split rim doesn't have them. Are they for lifting the gun for loading - e.g. aboard ship?
easyco69
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Posted: Sunday, January 04, 2015 - 06:06 PM UTC
tie downs for the gliders or air transport? Or for unloading with a crane from a boat?
The middle ring would be used to lift the gun from a crane..or in modern day..a helicopter.
SdAufKla
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Posted: Sunday, January 04, 2015 - 07:24 PM UTC
@ Steve: Thanks for checking the Osprey titles.

@ David: The hub rings are used for the attachment of the drag or hauling ropes. As noted by Steve, there is ample photographic evidence of this. Using drag ropes on arty and guns was very common among many armies at the time.

What's puzzling is the fact that these rim-tabs seem to only be present on British and Commonwealth arty and guns. This leads me to believe that there was some specific gun-related purpose intended for them.

I had thought about some reason having to do with the mounting of the tires or keeping them on the rims, but if this was the case, then why wouldn't these tabs have been used across all (or at least more) types of wheels? Again, they only appear on arty and guns.

In regards to tying down the pieces for transport, again, it would seem that if these were useful on arty and guns, why not just as useful on other types of equipment or vehicles?

I think some sort of leverage assist for moving the guns into and out of battery is the most likely answer, but how this was actually done using what tools or additional equipment remains a mystery (if indeed this is what their purpose was).

Someone out there must know of have access to an original manual with gun crew drill and procedures that would explain this.

Thanks again for the comments and ideas.
AFVFan
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Posted: Sunday, January 04, 2015 - 08:17 PM UTC
All the ideas I've come up with have already been covered in the previous posts. Now, I'm just watching the thread out of curiosity to see if anyone can come up with an answer.
18Bravo
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Posted: Sunday, January 04, 2015 - 09:29 PM UTC
As a 13B as well as an 18B, (albeit VERY shortlived) here are my thoughts:
While I don't know what they are for, I'll say that the least likely use is for adjusting the piece. I've been a member of a crew moving pieces around, and it's really not diffucult at all. Even some pretty large undulations in the ground are easily overcome because your mechanical advantage comes from the long-@$$ trail(s). (not to mention a good crew chief is going to choose a nice flat area to emplace it) If I had to speculate I'd say it might be to secure it to something - a palletized load or the inside of a lorry, and even that doesn't sound that plausible to me.
Perhaps a "real" artillery person can chime in.
ALBOWIE
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Posted: Monday, January 05, 2015 - 01:48 AM UTC
I asked this question of an old gunner regarding the 25 pdr in my very early Army days. His claim is that to haul guns up inclines, across rough terrain etc you used the guns ropes and pulleys. One end was attached to the tab then wound round the tabs in an under and over fashion, the other end went to an anchored snatch block and when the crew pulled the mechanical assistance of the snatch block and the rotational effect on the wheels made it easier to move the gun over rough and difficult terrain. Using the wheels gave it a little extra mechanical assistance. The poles stowed on the trails are used for levering the trials around and are too large a diameter to use as levers with the tabs.
I have no idea how accurate this information is as the gunner in question only served on 25 pdrs for a short time early in his career although he lamented the absence on the m2A2 guns that replaced them.
SdAufKla
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Posted: Monday, January 05, 2015 - 02:34 AM UTC
@ Bob: Hey, you rubber-necker, you! LOL! I know, by now I'm just curioser and curioser myself...

@ Robert: Well, I started out as an 11BS with an 11CS secondary when I graduated the Q-course in '79 and finished as an 18Z when I retired in '04 (was the Co. SGM for C/3/5 at the time).

Usually, I can suss-out these little gun-related widgets in fairly short order. (Hey, it really ain't rocket science.) After all some LCD GI (or Tommy, in this case) has to be able to use the thing when he's up to eyeball's in cold mud, at night, while someone else is shooting at him.

@ Al: This makes sense and fits with all the best guesses so far.

I'm starting to think, though, that how ever or whatever was the intended use, it was either so complicated or so ineffective that no once ever actually employed the rim-tabs for their design purpose.

This might account for why no one actually knows the answer anymore, and why after WWII, it appears that no one designed arty pieces with rim-tabs on the wheels.

Like little arty wheel appendixes, vestigial rim-tabs lost in the evolution of artillery. A good idea... that wasn't.

Still, like Foxx Mulder, I want to believe that there's an answer out there somewhere...
18Bravo
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Posted: Monday, January 05, 2015 - 03:35 AM UTC
Damn,
You're one of the only dudes I meet who predates me at the Q. (Class 1-83) Of course I went to the last hard class.
SdAufKla
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Posted: Monday, January 05, 2015 - 04:58 AM UTC

Quoted Text

Damn,
You're one of the only dudes I meet who predates me at the Q. (Class 1-83) Of course I went to the last hard class.



Danged whipper-snappers... LOL!

By then, I had already re-up'ed, finished DLI, and was on my way to Berlin and then on to Toelz.

I pretty much spent all my time either in 10th Group (or SWC) until I went to the academy at Ft. Bliss in '00. Then after I graduated in '01, in typical Army fashion, they sent a 3-3 German speaker to 5th Group - go figure.

Still, I know if I had gone back to Carson in '01, all I would have wanted was to go to Campbell anyways, so things work out in the end (sometimes!).

I imagine our paths crossed a few times somewhere in all that...
18Bravo
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Posted: Monday, January 05, 2015 - 05:17 AM UTC
C/2/10 in '83-84. Berlin after that. Carson from ''02 until now. Probably so!
SdAufKla
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Posted: Monday, January 05, 2015 - 05:30 AM UTC

Quoted Text

C/2/10 in '83-84. Berlin after that. Carson from ''02 until now. Probably so!



A small world, indeed! Berg Heil!
CMOT
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ARMORAMA
#406
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Posted: Monday, January 05, 2015 - 09:34 PM UTC
These tabs identify the wheels as an artillery wheel and are used for moving the gun on rough, boggy, muddy or soft terrain when a vehicle is not available. You attach a rope loop over one of the tags on each side and then wrap it around the other lugs, some poor saps then get the job of pulling the ropes to rotate the wheel. These tabs should only be found on an artillery piece.
Frenchy
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Posted: Monday, January 05, 2015 - 09:45 PM UTC
Reinventing the (artillery) wheel ?




H.P.
CMOT
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ARMORAMA
#406
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Posted: Monday, January 05, 2015 - 09:52 PM UTC
That rope position would make the gun go backwards .
tankmodeler
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Posted: Monday, January 05, 2015 - 11:21 PM UTC
Darren,

In Frenchy's photo, the rope is attached to a free-turning loop on the hub and not offset from it, so the guys are pulling the piece forward.

As for using the lugs on the rim for a similar effect, I don't think so. For starters you would only get part of a turn out of the wheel before you get to exactly the situation you describe in your post, the rope gets on the "wrong" side of the axis and you start to defeat the purpose.

I think they are for using a hand spike to slowly advance the piece over very rough or inclined ground using the hub as a base and the tab as a fulcrum. The fact that the tire bulges a bit past the "sheave" plane on the hub is pretty inconsequential if you are using a 4-5 foot long metal pole to do the job. The tire bulge will just be levered out of the way. That there are approximately matching grooves on the tabs and on the sheave would strengthen my surmise.

But I still don't _know_. :-)

Paul
CMOT
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#406
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Posted: Tuesday, January 06, 2015 - 12:56 AM UTC
Sorry Paul but that is what they are for, Information from the The Garrison who are re-enactors of WW1 and WW2 Royal Artillery, a large number of them ex-gunners.
CMOT
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#406
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Posted: Tuesday, January 06, 2015 - 01:25 AM UTC
this method allows the rope to act as a lever and so requires less effort by the donkeys doing the pulling.
Robbd01
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Posted: Tuesday, January 06, 2015 - 02:10 AM UTC

Quoted Text

Sorry Paul but that is what they are for, Information from the The Garrison who are re-enactors of WW1 and WW2 Royal Artillery, a large number of them ex-gunners.



Need to get The Garrison to re-enact it in use for us physics challenged - need pics of it in use

Cheers
CMOT
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#406
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Posted: Tuesday, January 06, 2015 - 02:13 AM UTC
I am sure I can manage that given time
tankmodeler
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Posted: Tuesday, January 06, 2015 - 04:25 AM UTC

Quoted Text

Sorry Paul but that is what they are for, Information from the The Garrison who are re-enactors of WW1 and WW2 Royal Artillery, a large number of them ex-gunners.


OK, I'm obviously not getting the picture here. :-)

So you wrap the rope around the tabs, rather like the rope on a windlass, anchoring one end to the hub and then pull the free end that you have let pay out the front thereby providing an extra torque to the wheel by virtue of the distance from the wheel hub to the rope strung across the tabs?

Wouldn't this mean you have to rewind the rope over the tabs every so often as you unwind the windlass?

If this is how it works, I can see the mechanical advantage, but it seems clumsy unless its used only in extremis and for very short distances.

If I haven't gotten it right yet, I'm obviously missing something and need pictures as well. :-)

Paul
CMOT
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#406
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Posted: Tuesday, January 06, 2015 - 04:42 AM UTC
Paul you are correct in that it is for short distance moves when needed depending on terrain. You would need to perform the task several times depending on distance, but a gun crew could move the gun over just about any terrain without busting a gut in the process. Of course you would not use this all of the time; the rope attached to the eye makes it easy enough to move a gun most of the time, when you reach a difficult patch you wrap the rope around the rim.