Armor/AFV: AA/AT/Artillery
For discussions about artillery and anti-aircraft or anti-tank guns.
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Dumb Question Time.
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Nevada, United States
Joined: June 17, 2016
KitMaker: 1,124 posts
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Posted: Tuesday, November 21, 2017 - 02:51 PM UTC
I've noticed that Soviet Artillery, ZIS-3 and the likes, use GAZ/ZIS truck tires. No brainer there. But it seems the rims are always mounted with the spoke side out. (With duel tires inner rim is spoke side out, outer one spoke side in.) I can see on a vehicle this being needed to go over the brakes. Any reason for this on the artillery?
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Rhone, France
Joined: December 02, 2002
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Posted: Tuesday, November 21, 2017 - 03:22 PM UTC
Maybe to reduce the track width of the carriage ?

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Stockholm, Sweden
Joined: November 29, 2006
KitMaker: 6,693 posts
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Posted: Tuesday, November 21, 2017 - 03:30 PM UTC
Force of habit? Front wheels (singles) are also usually mounted with the spoke side outwards.

Possibly it could also be a way of sligtly reducing the torque on the ends of the axles.
With the spoke side inwards the force from the ground pressing the axle upwards gets a longer torque arm, a few inches outside the end of the axle.
When the wheel is mounted spoke side outwards the force from the ground hits a few inches inside of the end of the axle instead.

The wheel also protects the brake drum and brake lines, could be something to consider for an off-road vehicle or trailer.

Track width, as Frency says above, is also a consideration. The length of the axle is given by the width of the gun carriage + brake drums and any other essential stuff.

/ Robin

BS-3 100 mm gun

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Ontario, Canada
Joined: November 03, 2012
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Posted: Tuesday, November 21, 2017 - 04:01 PM UTC
strength & balance? It would shear the bolts off in my opinion, if a single tire were used backwards. It's all about physics.
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Vilnius, Lithuania
Joined: April 12, 2017
KitMaker: 196 posts
Armorama: 196 posts
Posted: Tuesday, November 21, 2017 - 04:59 PM UTC
From design point, it is logical to hide steering suspension and brake elements inside rim. If you design it to be "reversed", you end up with dead space inside rims, and components exposed to potential damage. Doesn't make much sense.
You will not shear bolts, if axle is designed to have wheels reversed. Plus, forces on bolts will be the same (bolts only hold rim on flange, you dont have vertical or shear load on them). But what does change, is load on other suspension components, because by reversing wheel you lengthen the axle.
Then fenders and other components come into account, and finally, if its axle with steering, that one changes too.
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Washington, United States
Joined: March 15, 2009
KitMaker: 3,670 posts
Armorama: 2,052 posts
Posted: Tuesday, November 21, 2017 - 10:00 PM UTC
Just stumbled on this by accident-- and I might be all wrong here, but it seems to me it's just an easier way to add an outside pair of wheels to convert to "dualies" for better traction in rough terrain. It probably saves a little time and effort in adding the outside pair of wheels.
VR, Russ