The PT Boat Forum
http://www.ptboatforum.com/cgi-bin/MB2/netboard.cgi


Forum Category: PT Boats of WWII
http://www.ptboatforum.com/cgi-bin/MB2/netboard.cgi?cid=101&fct=showf


Forum Name: PT Boats - General
http://www.ptboatforum.com/cgi-bin/MB2/netboard.cgi?fct=gotoforum&cid=101&fid=102


Topic: Torque Rods on Elco Torpedo Tubes
http://www.ptboatforum.com/cgi-bin/MB2/netboardr.cgi?cid=101&fid=102&tid=3282



I see that they are there, on both the 21 inch tubes used on Elco 77 and 80 footers and the18 inch tubes on the 70 footers as well. I have been looking at them for decades! I know what they are called. But, I can't figure out what mechanical or structural function they fulfill. Does anybody, perhaps an old torpedoman, know what these rods did? The Higgins type fixed tubes had nothing like these, so maybe it relates to the training mechanism. Did the tubes want to twist or bend somehow?

Mike

Posted By: Michael Vorrasi | Posted on: Jul 26, 2013 - 9:11am
Total Posts: 72 | Joined: Jul 1, 2013 - 11:46am



As I understand it, the torque rods were used to stabilize the tube saddles. pp 212-213 of the Lambert/Ross ALLIED COASTAL FORCES V.II has a full explanation...

Will

Posted By: Will Day | Posted on: Jul 26, 2013 - 12:16pm
Total Posts: 1955 | Joined: Oct 8, 2006 - 4:19pm



Thanks Will. Actually, that page in ACF Vol2 is what prompted my query. It mentions that the torque rods were to stabilize the saddles. But the last version of the 21 inch tube (not one I have seen in any PT photos) did away with the rods. So I was wondering if they really did anything useful. It appears they were there merely to align the fore and aft saddles, but the mounting bases and the tubes themselves would have done the same thing on each tube once the saddles are clamped down on the tubes. Seems like a bit of over-design.

Mike

Posted By: Michael Vorrasi | Posted on: Jul 28, 2013 - 7:25am
Total Posts: 72 | Joined: Jul 1, 2013 - 11:46am




Thanks Will. Actually, that page in ACF Vol2 is what prompted my query. It mentions that the torque rods were to stabilize the saddles. But the last version of the 21 inch tube (not one I have seen in any PT photos) did away with the rods. So I was wondering if they really did anything useful. It appears they were there merely to align the fore and aft saddles, but the mounting bases and the tubes themselves would have done the same thing on each tube once the saddles are clamped down on the tubes. Seems like a bit of over-design.

Mike


Ahoy there.

Don't forget that Elco torpedo tubes were cranked outboard prior to launching the torpedoes. I think that is why the torque rods were added to the mounts.-In this case torque could cause twist.

"Give me a fast boat for we want to get out of harm's way too."

Posted By: PeterTareBuilder2 | Posted on: Jul 28, 2013 - 11:42am
Total Posts: 204 | Joined: Dec 8, 2012 - 6:03pm



Take a look at the tubes on this shot of PT-196. No Torque Rods. Must be the final version of the tube. Also, the cradles look different here too.

[url]http://www.usmilitariaforum.com/uploads//monthly_06_2009/post-68-1246221357.jpg[/url]


[image]http://www.usmilitariaforum.com/uploads//monthly_06_2009/post-68-1246221357.jpg[/image]


Also, see this shot of PT-333, also, no torque rods and the newer cradle:
[url]http://www.history.navy.mil/photos/images/k03000/k03914.jpg[/url]


[image]http://www.history.navy.mil/photos/images/k03000/k03914.jpg[/image]


Mike

Posted By: Michael Vorrasi | Posted on: Aug 20, 2013 - 7:04am
Total Posts: 72 | Joined: Jul 1, 2013 - 11:46am



Okay, I'm closing in on the point the tubes were changed. This shot of PT-178 shows original Torque Rod tubes in place with bee hive radar;

[image]http://www.navsource.org/archives/12/120517603.jpg[/image]
[url]http://www.navsource.org/archives/12/120517603.jpg[/url]

and here in the earliest boat I could find with the new tubes, PT-183:

[image]http://www.navsource.org/archives/12/120518002.jpg[/image]
[url]http://www.navsource.org/archives/12/120518002.jp[/url]

What is of great interest on 183 is the transitional stage with racks installed aft, but tubes still forward. The small size of the new type cradles and no top strap to clamp the tubes down, like the early tubes have, leads me to believe Elco simplified and lightened the cradles by welding the tubes onto them. Thus welded, there would be no twisting motion or alignment issues that would give rise to the need for torque rods, thus explaining their elimination.

While rooting around for those two shots, I found this additional photo of PT-196, In addition to a better look at the small cradles and no rods, note the 196 already has a 40mm installed and the new style engine room air scoop hatch.

[image]http://www.navsource.org/archives/12/120519601.jpg[/image]
[url]http://www.navsource.org/archives/12/120519601.jpg[/url]


Mike

Posted By: Michael Vorrasi | Posted on: Aug 20, 2013 - 4:39pm
Total Posts: 72 | Joined: Jul 1, 2013 - 11:46am