CCKW cargo bows.. I think I figured them out

[deadline]

The long held idea is that the WWII era bows are the same as current production (well, 1990s) cargo bows.

 

I found that all of the bows that I have collected off CCKWs have a tell tale notch. None of the M35 bows have this notch.

 

I have all the images, manuals and discussion at:

 

http://www.tm9-801.com/forums/viewtopic.php?f=2&t=627&p=1277#p1277

 

Not sure what the rules are, but I don't think I can put those images on this server.. but I would like everyone to look it over and if there is anything that blows my theory out of the water please post here.

[Big ray]

I suspect that the notches are to prevent cracking on the radius......... unless someone knows better?????

[deadline]

I can only assume that the two halves were stamped, then spot welded. There is little need for stress relief in an part stamped by a multi-ton press. The metal will flow under pressure. If the part were rolled, OK, that would indeed generate stress.. but the notch is not at what I would consider the point of highest stress. The most convex part has a very significant cutout.

 

None of the current prodcution (M-series) bows have that notch. Also the notch varies. I've got pictures of a simple slot, to a triangle, oval, ellipse and half circle. The only thing in common is the location.

 

 

 

This image shows 2 CCKW bows (left w/red circle) and 2 M series (right w/blue circle)

 

Note that about 1 inch (2.5cm) below the portion that is set back.. this has nothing to do with stress either, it that section were straight, the flange would protrude over the bottom, inset part. So they cut it back.

 

Also, why is there no stress relief for the bottom radius? Its actually a smaller radius than the upper one... so a tighter radius would mean more metal to 'move' and therefore more 'stress'. But, as I said since I believe that these parts were formed in a press of suitable tonnage the metal would simply flow (actually the reason you need to much tonnage is to get the metal to deform past is elastic limit resulting in the desired permanent shape... aka no need for any stress relief.

 

I will look on the side part for a notch.

 

Like I said, I have more images and explanation (including TM references) at http://www.tm9-801.com/forums/viewtopic.php?f=2&t=627

Edited November 6, 2011 by deadline

[N.O.S.]

I reckon the notch could be more to do with alignment in an assembly jig.

[deadline]

That's the conclusion I have reached.... its an assembly remnant.

 

But the more important discovery is that no M-series (post war) bow that I have has one. Thus is can be used to discriminate between 'proper' and post war parts.

 

If you read the link I posted it has my full discussion... there are to many photos to repost here.