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The Tetrarch Was Really, Really Weird

snake-tracks tetrach historical mechanical suspension

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collimatrix #1 Posted Oct 16 2012 - 17:32

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I had always written off the tetrarch as a sort of generic light tank, maybe a late-surviving descendant of the early tankette designs or what have you.

Nope.  The tetrarch is actually one of the least mechanically orthodox production armored fighting vehicles.

The running gear is bizarre.  Those road wheels can actually pivot.  Yes, that's right, pivot; as in the plane of the roadwheels could be tilted with respect to the forward axis of the vehicle, just like the wheels on a car.  This meant that the track links had two degrees of freedom; unlike every other track design ever on a production vehicle which have a single hinge and are laterally rigid.

This meant that, again, unlike every other production tracked vehicle ever made, the tetrarch did not skid-steer, at least for gentle turns.  For tighter turns it did skid-steer, so again, unlike every other production tracked vehicle ever made, the tetrach actually had two modes of steering.

Oh, yeah, and the suspension was hydropneumatic as well.

Frickin' weird.

Will_of_Iron #2 Posted Oct 16 2012 - 17:56

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Wow, that is cool for it's time, even for our time. Glad I still have mine. It has a great gun for such a little thing too.

akoaih #3 Posted Oct 16 2012 - 18:02

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The British Universal Carrier also had track warping.  The center bogies (on each side) were connected by a shaft through the vehicle.  When the steering wheel was turned it shifted the shaft, and thus the bogies, from side to side, warping the track and causing the vehicle to turn.  On tighter turns the steering linkage would also engage the brake in the direction of the turn.

The US license-built version of the carrier (T-14 I think it was called) made some modifications to the design, including removing the track warping due to its complexity.

Edited by akoaih, Oct 16 2012 - 18:03.


Whee #4 Posted Oct 16 2012 - 18:02

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It's a good tank, in fact really good.

collimatrix #5 Posted Oct 16 2012 - 18:13

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View Postakoaih, on Oct 16 2012 - 18:02, said:

The British Universal Carrier also had track warping.  The center bogies (on each side) were connected by a shaft through the vehicle.  When the steering wheel was turned it shifted the shaft, and thus the bogies, from side to side, warping the track and causing the vehicle to turn.  On tighter turns the steering linkage would also engage the brake in the direction of the turn.

The US license-built version of the carrier (T-14 I think it was called) made some modifications to the design, including removing the track warping due to its complexity.

Interesting.  Do you have a picture?  The book I'm reading states that the UC only had brake-steering.

Xlucine #6 Posted Oct 16 2012 - 19:00

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View Postcollimatrix, on Oct 16 2012 - 17:32, said:

This meant that, again, unlike every other production tracked vehicle ever made, the tetrarch did not skid-steer, at least for gentle turns.  For tighter turns it did skid-steer, so again, unlike every other production tracked vehicle ever made, the tetrach actually had two modes of steering.

It even had a steering wheel instead of the normal brake levers - one weird beast. It arose because vickers wanted to export a light tank, however the suspension they used on previous lights was designed with government help and so they couldn't sell it - so they started from scratch, and decided to mix things up a bit. It can even run without the tracks fitted as the drive sprocket is one of the road wheels

Also the shape is cute as hell. The harry hopkins sucked in that regard - while it had a better ballistic shape and had actual armour worth a damn it was nowhere near as good looking

blurr91 #7 Posted Oct 16 2012 - 19:24

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It did look like it could run, or designed to run, without tracks.  The pivoting road wheels prove that.

Brits always come up with some bizzare engineering designs just to see what would happen.  :Smile_teethhappy:

Sometimes they hit a homerun (Harrier, the tank, angled flight deck, the Wooden Wonder).

Sometimes they are just meh...

akoaih #8 Posted Oct 16 2012 - 20:09

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View Postcollimatrix, on Oct 16 2012 - 18:13, said:

Interesting.  Do you have a picture?  The book I'm reading states that the UC only had brake-steering.

The Osprey book, by David Fletcher, has a nice cutaway drawing showing the linkages.  Odd thing, no matter how many times I traced the linkages it appeared that hard steering would engage the brake on the outside of the turn, but maybe I missed something along the way.

If the Tetrarch was a wheel and track design then that also was not unique.  That appears to have been a popular idea at the time since the tracks of the era had limited lifespan.  The tank could drive much faster and with less wear and tear to the battle area then attach the tracks for combat.  John Christie's first designs were for wheel and track vehicles; his independent road wheel suspension came later.  It's said that a crew of the Christie designs could remove or engage the tracks in about 30 minutes.

OT, yes, the Tet rocks.

The_Chieftain #9 Posted Oct 16 2012 - 22:13

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View Postakoaih, on Oct 16 2012 - 18:02, said:

This meant that, again, unlike every other production tracked vehicle ever made, the tetrarch did not skid-steer, at least for gentle turns.

Except for the most produced armoured fighting vehicle of all time, of course.

View Postakoaih, on Oct 16 2012 - 18:02, said:

The British Universal Carrier also had track warping.

There we go... :)

collimatrix #10 Posted Oct 17 2012 - 07:13

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Well, now I feel like a rank amateur.  I suppose it's one way to learn...

Chieftain, is a Tetrarch or Universal Carrier episode coming up on an episode of Inside the Chieftain's Hatch?

akoaih #11 Posted Oct 17 2012 - 14:50

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View Postcollimatrix, on Oct 17 2012 - 07:13, said:

Well, now I feel like a rank amateur.  I suppose it's one way to learn...

Chieftain, is a Tetrarch or Universal Carrier episode coming up on an episode of Inside the Chieftain's Hatch?

I was a rank amateur once, then I took an arrow to the knee.

Xlucine #12 Posted Oct 17 2012 - 15:15

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View Postcollimatrix, on Oct 17 2012 - 07:13, said:

Well, now I feel like a rank amateur.  I suppose it's one way to learn...

Chieftain, is a Tetrarch or Universal Carrier episode coming up on an episode of Inside the Chieftain's Hatch?

Conqueror first!  :Smile-angry:  I wonder how receptive bovington would be to you filming there, chief?

Spanktankk #13 Posted Oct 17 2012 - 15:17

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My TET is one tank I'm NEVER gonna sell, even tho I dont get to play it much  :Smile_Default:

The_Chieftain #14 Posted Oct 17 2012 - 18:05

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View PostXlucine, on Oct 17 2012 - 15:15, said:

I wonder how receptive bovington would be to you filming there, chief?

Good question, and it's on my list of things to ask them.

But I don't need to, as I have a perfectly good Conqueror right here.

trowzerkoff #15 Posted Oct 20 2012 - 20:41

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Armoured cars were a key concept in British WW2 doctrine.  

The Tetrarch was conceived as a light-weight tracked armoured car for glider/airborne troops.  As a quirky hybrid, it was supposed to do armoured car scouting jobs [its primary task] but with a bit more cross country capability than a heavy wheeled unit such as a Humber or Daimler.

As is visually self-evident, for sensible pragmatic and production reasons the Tetrarch's turret is a direct carry over from the Daimler and the hull uses many aspects of the Daimler's and Humber's engineering drawings.

Xlucine #16 Posted Oct 21 2012 - 01:54

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View Posttrowzerkoff, on Oct 20 2012 - 20:41, said:

The Tetrarch was conceived as a light-weight tracked armoured car for glider/airborne troops.

No - it was conceived as a light-weight tank thingy, the airborne bit came later (if a tank was designed for the role it ended up filling them the ministry of supply would have thrown a fit)

trowzerkoff #17 Posted Oct 21 2012 - 20:17

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View PostXlucine, on Oct 21 2012 - 01:54, said:

No - it was conceived as a light-weight tank thingy, the airborne bit came later (if a tank was designed for the role it ended up filling them the ministry of supply would have thrown a fit)

Quite right - my mistake.  Yes, its original concept was one of a conventional light tank.  However it seems that mainstream tanks and armoured cars got more capable and so the Tetrarch ended up as a bit of an orphan.

Baron_de_Pencier #18 Posted Oct 23 2012 - 15:48

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Isn't  the idea of flex-tracks older than the idea of tanks? I seem to recall reading an article somewhere about an Australian inventory who developed a really good flex-track system in 1905 or something and tried to give it to the British army, which rejected his proposals.

Does anyone else remember this?

Wyvern2 #19 Posted Oct 24 2012 - 05:32

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Tetrarch was the light Mk VII and the MK VIII was the Harry hopkins that never saw service. However, the light tank concept was replaced with armored cars by the british in~1941ish and so the Tetrarch had no place, other then the 20 sent to russia and half dozen used on Madagascar against the frenchies. That still left about 150 that were produced and the british figured out that they could be carried in a Hamilcar glider, do they did, though i think the only company sized landing of airborne tetrarchs was the 6th AARR in Normandy. A more important contribution from the tetrarch was the experimenting on the squeezebore/littlejohn adaptor and the use of its turret on the Daimler Mk1 Armored car. Too bad WG says no armored cars, especially considering it was a key part of British(and German) recon equipment and strategy, unlike the light tanks of other nations

Xlucine #20 Posted Oct 24 2012 - 13:52

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View PostWyvern2, on Oct 24 2012 - 05:32, said:

...That still left about 150 that were produced

Only 100 total were ever made IIRC

Quote

i think the only company sized landing of airborne tetrarchs was the 6th AARR in Normandy.

Correct

Quote

A more important contribution from the tetrarch was the experimenting on the squeezebore/littlejohn adaptor and the use of its turret on the Daimler Mk1 Armored car.

Straussler's first DD tank was a tetrarch