School of the boat for 11-11-08 (torpedo tubes Part 2)

[Darrin]

Okay folks,
Before we put the buggy before the horse when it comes to water slugs and maintenance of these incredible pieces of equipment of the submarine that made the japanese empire crumble and fear that the submarines of the US Navy were in their area and hunting THEM!

We need to talk about the basics about these tubes and what they did...  SO with this weeks school of the boat we are going to talk about a chapter that is easy yet so intriguing in my opinion because once you get an understanding of these tubes you can sink a ship in a matter of seconds if your TM's screw something up....

With that being said we are going to talk about the breech and muzzle door operation and the associated equipment to load and fire the weapons that JT was so nice to inform you about

HAPPY VETERAN'S DAY ALL!!!!

and of course good luck to all who wish to participate in these School of the Boat's and for hopefully for those who come after these Schools have run their course.

[JTheotonio]

Is this a "breech" of contract?

We barely "breeched" the subject of those wonderful 21" submerged torpedo tubes.
(There is a difference between tubes used on surface craft, those on submarines.)

[JTheotonio]

come on guys - they're big round brass things.  Anyone have a spare? I'd sure like to have one down in my submarine room!

[Mark Sarsfield]

I'll try to make a reply by COB today (not Chief of the Boat).

[etkfixr]

Okay, I'll take the first whack at it.  Loading: the tubes are loaded the way God intended, with ropes and pulleys and the sweat of manly men.  There is one set of ropes and pulleys to push the torpedo in and another to act as a snubber, to keep it under control.  The ropes reverse purpose to pull a torpedo out for servicing.  The torpedo has a guide on top that mates with a slot in the top of the tube, the torpedo goes in until it hits the torpedo stop.  The breech door is manually operated and serves three purposes, it keeps the sea water out when the muzzle door is open, it contains the impulse air charge so that it pushes the torpedo out and it has a torpedo tail stop to hold the torpedo against the forward stop.  The muzzle door is hydraulically operated, manually in an emergency and the two doors are interlocked so they don't open at the same time.  Somebody else jump in off the ropes for the tag and take it from here.  Terry

[JTheotonio]

Before loading a tube you should know some parts so that you can open the door.  Breech end is in side the boat - it's that nice looking round brass things you see at the forward end of the room. The muzzle door is the one outside.

So here are some pictures of the breech door.  Some one needs to tell us about some of the important parts of the breech door and how you open and close it.

 

[JTheotonio]

Here are the rest of the pictures

[Darrin]

Thanks John,

had shoulder surgery on Friday and having to type with my left hand, so it takes me a while to type a simple message

[JTheotonio]

What happened?   

[Darrin]

worn out after 18 years of active service to 2 branches of service and a broken collar bone 25 years ago have earned me a arthoscopy surgery on my right shoulder.. am typing with 2 hands right now and it hurts but I don't mind much just as long as I am talking to a shipmate....  The doc expects me to make a full recovery in the next couple of months and I can only hope that he is right..

John,
please keep track of the school of the boat for me and keep these miscreant's of the deep straight, I have learned that you are a shipmate and a friend and I would like to hoist one or two to you in the near future.

Darrin

[Lance Dean]

Recover well Darrin.  It's a terrible thing to not let something heal properly.

[Darrin]

already went back to work today for a couple of hours... speaking of BACK TO WORK...... There are some unanswered questions of the school of the boat and I for one am not going forward with this weeks question until the previous weeks questions are answered

[etkfixr]

Okay, breech door 101.  The door itself, obviously.  The big ring around it is the locking ring to hold it closed.  Its opened by the macho torpedoman's arm holding the wrench in the second photo.  There are two sight glasses and a pressure guage to help check if it is safe to open the door.  The big twisty knob in the middle is the torpedo tail stop, it holds the torpedo in place.  Notably lacking are "A" cable plugs and guidance wire tube and cutter, etc. on modern tubes.  Anything else?  PS did they undog the locking ring almost but not quite all the way and then try to wiggle the door before opening it?  That was SOP on the Jackson in case the tube was full or under pressure, etc.  Terry

[Darrin]

the vents were opened along with the drains prior to opening a tube open, and there are connectors for an "A" cable on the tubes in the boats that were modified over the years.. Great job!
You were a TM weren't you??

[JTheotonio]

  OK, I guess I need to give everyone a little nudge to get this portion of our SOB moving forward again.

Darrin was looking for some information about the Mk31-39 21” submerged torpedo tube doors and their operation. 

So let’s start with the breech door.  This is the inboard or loading end of the torpedo tube.  It is a bronze casting that is bowl-shaped.  It has eight lugs that fit with the corresponding lugs on the inner surface of the locking ring.  On the outside of the breech door are two hinged arms connected to hinge brackets that allow the doors to swing open and close.  The hinge brackets are attached to the barrel of the tubes. Starboard doors will swing outboard (towards starboard), and the port side doors will also swing outboard (towards port).

On each door you will find a pressure gage, a reflex crater gage, a hand grip, and a hand wheel for operating the torpedo tail stop.

On the inner surface of the door you find a ring-like grove (referred to as an annular) for a rubber gasket that will fit into a grove cut into the bead-end of the barrel. This forms a water-tight seal when the door is closed and locked.

So now that describes the breech door.  We’ll leave all of the pinion gears, and stuff out for now. 

Important safety point: never open the breech door with the muzzle door also opened.

Can any one now describe the various interlocks on the muzzle door?  Also, once you describe the interlocks, describe how the muzzle door is opened and closed.

What is the purpose of the reflex water gage? On earlier boats the reflex water gage had a larger hole.  Why was it reduced in size?
What is the purpose of the pressure gage? What is the purpose of the pressure gage check valve?