View Full Version : Is this a Maxon turrent with Polsten 20mm

Deaf Smith
02-15-2010, 11:54 PM
I know it's not a Skink turret, but Maxon?

And if it is a maxon.. any idea when it was made?



02-16-2010, 05:32 PM
Hello Deaf, :)
From My reading of the article you attached, I'd say the pictured quad turret was a British copy of the Maxson, since it has in common all the Maxson features, as outlined in the bottom paragraph.
If I'm correct, then I'd suppose it could be argued it *is* a Maxson, or close enough to it and though I have no actual name to give it, I'd be prepared to label the pictured quad turret as "Britmax 4x20" until a better name is discovered.

Looking at the trailer the turret is mounted on, I'd hazard it was manufactured sometime around May of 1943, manly because the tires seem to be closer to the US pattern than British, while the wheels themselves appear to be British. Which would mean those tires being available to use or copy, which in turn would point to roughly mid-43.

I do recall seeing a couple of these in my childhood, they were unrestored, and had no labelling/nameplates on them, suggesting this may have been due to being "illegal" as in unlicenced/plagiarised copies of Maxson technology.

By comparison, the usual British mechanisms for turret controls are not mentioned at all, indicating this was not related to one of the usual crop of Boulton-Paul or Fraser-Nash Turrets then in use in bombers, and which employ a completely different control mechanism for hand (and sometimes foot) controls.

Sorry I can't be more helpful, Deaf.

Kind Regards, Uyraell.

02-16-2010, 06:02 PM
Was this even used by U.S. forces? It looks like a Commonwealth weapon system (more or less)...

Deaf Smith
02-16-2010, 10:00 PM
Now here is my gripe.

During WW2 the Navy (U.S. that is) made a weird quad 20mm mount, kind of like a bucket, late in the war. I think it was the marks 15, 22 and 26.



Why, oh why didn't they just get the Maxon, or this Brit version, and do this earlier? And since we made twin 20mm Oerlikon mounts, can you visualize mouting FOUR of those twins on this Brit Maxon (that's 8 Polstens giving 6000 rounds a minute, like a Vulcan.)

I know it's not as effective as the quad 40mm, but considering the size and weight, it would have been useful. Just 1/4th a second of hits is 25 rounds of 20mm.

Another view of this Quad. To me this beats the Quad .50 (and I like that weapon to.)



02-17-2010, 07:45 AM
Was this even used by U.S. forces? It looks like a Commonwealth weapon system (more or less)...

That was part of my point, Nick. The back of my mind (and some memory of having read this in My teens) says the Brits simply copied the Maxson major principles without licencing from Maxson. So long as the turret shown in Deaf's attachment was not issued to any US Forces, the Brits could blandly claim no laws or agreements had been broken.

By the same token, Deaf's point about the US forces not having access to the turret he asked about is also answered.

(As an aside, Deaf, there was a huge rivalry between Army and Navy, such that Navy would go to great lengths to obtain equipment for it's own use, and which was of different design to the Army equivalent, even in cases where the Army equivalent was clearly superior.
Vast amounts of money were squandered that way, as both Army and Navy effectively had their 'own private contractors" in much the same way as in Germany the SS had private contractors.
This factor also accounts for why the Navy would most likely not adopt a system such as you posited, even had it been available: if the Army had been involved with it in any way, the Navy would deliberately NOT want it, no matter how good or useful it might be.)

Meanwhile, Brit or Commonwealth troops could be issued with them, because, in effect, the Americans "didn't know".

This would also account for why I saw no maker's nameplate on the two examples I saw when younger, nor any place where said nameplate might have been attached/welded/riveted.

Kind Regards, Uyraell.

02-17-2010, 04:12 PM
Interesting, sorry I didn't read your comments as I was in a hurry and meant to post this last night after doing some looking around...

Deaf Smith
02-17-2010, 07:19 PM
Well then Uyraell, I realize our Navy/Army rivalry was not as bad as Japans, but still, considering our GIs lives were at stake, I think it was stupid. I'm a firm believer that when the gong sounds all rivalry goes out the window and the only thing that matters is winning. And the best is not good enough for those on the sharp end of the stick. You give the GIs the best you can get, money be danged.

That rivalry not only cost us the loss of use of the Maxon, but the Polstens. I've look at it alot and I wonder if it was better than the Hispano. And I just loved that Maxon 20mm. And the Skink turret I could see that on a M3 Stuart.

Oh, and BTW I goofed up on the math above. I was thinking M2 Browning and not 20mm RPMs. Still that Maxon with 20mm would have been the way to go, no matter if it was the UK or US using it.


02-18-2010, 06:45 AM
Deaf, I'm in agreement with you: give the troops the best, NOT the cheapest or politically most convenient.

Nick, no worries my friend, it is, after all, a rather obscure topic, even in equipment terms.

As for My seeing the two turrets I did when young, I doubt any one much at all paid attention to them back then: there seemed to be a huge but silent effort to ignore all such things as being "part of a dead past". This, of course, quite absent of the realisation that the past shapes the current era and the future.

Deaf, I *have* seen that Navy quadbucket before, tho I cannot say I recall it being developed sufficiently to have seen operation in combat. That said, years ago when I was reading info on the "Skysweeper" Tracking-computing-autoloading twin 57mm AA gun, I seem to recall mention of experiments done with the same quadbudket in relation to manual reversion (backup) control as were to be employed in Skysweeper. Memory doesn't recall more than that, but the irony is that Skysweeper was one of very few programs where Army and Navy ever came close to cooperation in development, because the "need was the same", for once.

Regarding the Polsten being better than the Hispano: Panzerknacker or Tony Williams may well correct me on this, but as I recall the Polstens was slightly less accurate, but much less prone to feed jams, and much easier to clear if it suffered a jam. Nor were the Polstens as demanding, cooling-wise. The Polstens were also easier to harmonise to a cone of fire onto target, and about only 45% the cost of either a Hispano or Oerlikon to manufacture, because the Polstens only had about 60% the number of individual parts in total, and about 30% more stamped, as opposed to machined parts.

Kind Regards Deaf and Nick, Uyraell.

Deaf Smith
02-18-2010, 07:39 PM

This might help.


Quad Mounts Marks 15, 22 and 26

2) Mark 15 was a quad mount originally designed for PT boats but was not a serviceable design. Mark 22 was a power-operated quad mount with the operator seated within the mount and was used in several ships in 1944-45. Mark 16 was the standard post-WWII mount, in 1982 it was described as unreliable and difficult to maintain and was phased out in favor of the 25mm chain gun.

And here is a picture of one on the Massachusetts (BB-59) I guess they called it the 'Thunderbolt'.


The "Thunderbolt" was an attempt to increase 20mm hitting power. At night, the continuous stream of tracers from the "Thunderbolt" gun, like the beam of a searchlight, hurled destructive 20mm projectiles at 1800 rounds per minute at an enemy.

Designed as a dual-purpose weapon, it had an elevation/depression range of +85/-15 degrees and full traverse.

Two units were mounted on the Massachusetts (BB-59) and Maryland (BB-46) to augment their batteries and retained the Mark 14 gun sight.
By June 1944 it had been authorized also for Arkansas (BB-33), Colorado (BB-45), West Virginia (BB-48) and Washington (BB-56) and the training ship Wyoming (AG-17).

The Pacific Fleet recommended further installations in view of the success of the first two but nothing came of the project, partly because BuOrd considered the 20mm most valuable as a free-swinging weapon which could still be used after all shipboard power had been lost.

The mount consisted of a quadrant-shaped armoured gondola with four guns.
The gondala sides and back were constructed of 1/4in plate with a 1/2in front plate.

A tubular handle was attached to the rear of the gondola which permitted manual elevation and traverse of the mount in the event of an electric or hydraulic failure.

It had a gunner's seat with joystick and firing treadle fitted to port.
An oil filter and recuperator were fitted to starboard.

There were slots for shell ejection and manual cocking of the 20mm cut in the rear.

The gondola pivoted on two vertical yokes wit elevation and depression effected by an hydraulic ram on each yoke.

The yokes were attached to a conical base which contained an electrically-driven hydraulic traversing motor.

Installation of the mount required the addition of a 24-volt DC generator.
The "Thunderbolt" weighed about the same (560lb) as the more powerful 40mm (single) mount.


And this is a heck of a resource! NAVY MANUALS AND DOCUMENTS ONLINE



02-18-2010, 11:58 PM
Many Thanks , Deaf ! , :)
Truly useful links indeed. I'm am enjoying the read, and have marked them.

Kind regards, Uyraell.