Figure 13 INBOARD SIDE OF TUBE BARREL

Figure 14 BOTTOM OF TUBE BARREL

Figure 15 OUTBOARD SIDE OF TUBE BARREL

In some tubes in earlier submarines, the barrel is of the same thickness throughout, except where bosses and pads are cast on to receive various fittings or parts of the operating mechanism. In submarine torpedo tubes of current construction, however, the interior finish is maintained on only four surfaces or "lands" (top, bottom, and both sides), the rest being recessed. In all cases, however, the finished in side diameter of the tube is 21.125 inches.

The bosses and pads cast on the barrel to receive the various fittings or parts of the operating mechanism, are shown in the keyed illustrations at the left (Figures 12, 13, 14, and 15). These four views show the barrel for a lower port bow tube. In the first three, the barrel has been turned over to show, first, the top, then the inboard side, then the bottom. In the lower view, Figure 15, the barrel has been turned around, end for end, to show the outboard side.

The pads and bosses include the following: Breech door hinge bracket pad; firing valve pad; poppet valve operating mechanism pad; roller trip pads (only one of these being used, the Mark of torpedo to be fired from the tube determining which one) vent pad (as shown, the forward vent on bow tube, after vent on stern tube); torpedo stop pads (the stop bolt being interchangeable from one to the other, according to the Mark of torpedo loaded) speed setting mechanism pad; depth setting mechanism pad; tripping latch pad; vent pad; stop cylinder and valve pad; interlocking mechanism breech bracket pad; poppet valve pad; acme thread, which

The significance of each of these bosses and pads, and their relation to the torpedo tube as a whole, as well as to its operation, will be more fully explained in their proper order on the following pages of this pamphlet.

Figure 16 shows a view of the interior of the

Current torpedo tubes are of two lengths, bow tubes being 252 inches, stern tubes 276 inches, over all length, not including doors. The effective length (the greatest length of the torpedoes that can be loaded into the barrel) for a barrel 252 inches over-all would be 250.81 inches; for a barrel 276 inches over-all, the effective length would be 274.81 inches.

Running through the top inside surface, or land, is a guide slot, 1 3/16 inches in width (as shown in Figure 16) which engages the guide stud on top of a torpedo to prevent it rotating while being ejected from

Along the bottom of the barrel are four rollers, mounted in brackets bolted to the bottom of the barrel. These rollers support the torpedo, and facilitate its movement while being loaded into and ejected from the barrel. In other words, the torpedo rides on these rollers during its movement through the barrel. Each roller bracket has a drain connection to prevent retention of water.

In some earlier torpedo tubes, a relief valve was fitted near the muzzle end of the barrel to vent the barrel whenever its pressure exceeded the pressure of the sea by more than ten pounds per square inch, and thereby prevent injury to the hinge of the muzzle door. It has been found, however, that under such pressure differentials the tube will vent through the muzzle door without injury to any part, so such valves are no longer fitted on tubes.

These mechanisms, some of which have been briefly referred to in the foregoing pages showing the pads and bosses on the barrel, control the opening and closing of the breech and muzzle doors;

The position or location of these various mechanisms on the tube are shown, not necessarily in their proper order or relationship, in the keyed

Figure 17 TOP OF TUBE

Figure 18 INBOARD SIDE

Figure 19 BOTTOM OF TUBE

Figure 20 OUTBOARD SIDE

A-Tripping latch arm, connects from cam on breech door hinge to operating shaft, and raises or lowers the tripping latch which trips the starting lever on the torpedo as it leaves the tube.

B-Firing valve, releases charge of compressed air into the tube to shoot the torpedo out of the tube.

C-Poppet valve, which draws off the charge of compressed air that shoots the torpedo out of the tube before the air can escape into the sea and create a disturbance on the surface of the water which would disclose the location of the submarine.

D-Interlocking mechanism breech bracket, the central point of the interlocking mechanisms which prevent improper operation of the tube.

E-Firing mechanism stop cylinder and pilot valve, into which air is admitted by the stop cylinder valve to set off the firing valve; with the interlock shutter bar which locks or releases the piston rod of the torpedo stop cylinder.

F-Electric firing solenoid, an electrical plunger magnet which opens the stop cylinder valve when the firing mechanism is operated.

G-Poppet valve indicator, which shows whether the poppet valve is open or closed.

H-Gyro setting mechanism, which sets the angle at which the torpedo travels.

I-Depth setting mechanism, sets mechanism controlling depth under water at which torpedo travels.

J-Speed setting mechanism, which, when its spindle is set in its socket in the torpedo, sets the speed at which the torpedo travels.

K-Breech bracket, same as (D).

M-Hand firing key, used for firing the torpedo when electric circuit is not operating.

N-Gyro setting mechanism, same as (H).

O-Depth setting mechanism crank, for operating depth setting mechanism (I).

P-Speed setting wheel, for operating speed setting mechanism (J). A crank is used instead of a wheel in later installations.

Q-Torpedo stop, which engages the guide stud on the torpedo and holds the torpedo in its proper place in the tube so the spindles for the depth setting mechanism, the speed setting mechanism, and the gyro setting mechanism will engage their proper sockets in the torpedo.

R-Roller brackets, four in number, on the under side of the tube, and in which are mounted the rollers on which the torpedo rides while going through the tube.

S-Muzzle door operating shaft, which connects with the gearing for opening and closing muzzle door.

T-Muzzle door hinge bracket. U-Housing for muzzle door gearing, connected with operating shaft (S), for opening and closing the muzzle door. (Not installed on tubes designed for power operation of muzzle doors.)

V-Roller brackets, same as (R).

W-Openings for torpedo tube drain pipes, fore and aft, for draining the water from the tube after the torpedo has been ejected and the muzzle door is locked closed, also for flooding the tube.

X-Torpedo stops, same as (Q), only one of these being used, depending on the Mark torpedo being used.

Y-Roller trip bracket, for the roller trip, or roller crank, which contacts the side of the torpedo until the sloping body of the torpedo allows it to move to set the poppet valve operating mechanism in action.

AA-Tripping latch shaft, connects with (A) at the breech door end of the barrel, and with the tripping latch, which trips the starting lever on the torpedo as it is leaving the tube. The tripping latch is raised as the breech door opens to permit loading the torpedo without interference, and it is lowered as the breech door is closed.

BB-Flange for the poppet valve drain pipe, for disposing of the poppet valve discharge, and which, in more recent submarines, runs to an open tank beneath the working floor.

CC-Flange for impulse air pipe, which connects the impulse tank with the firing mechanism, so that, as the firing mechanism is set in operation by pressing the firing key, a charge of compressed air is released into the tube behind the torpedo to eject the torpedo from the tube.

DD-Check valve, which prevents water from entering the firing system when the tube is flooded.

EE-Breech door bracket, bolted on the outboard side of the tube, and to which the breech door is hinged.

FF-Firing valve, same as (B).

GG-Electric firing solenoid, same as (F).

HH- Poppet valve, same as (C).

II-Depth setting mechanism, same as (I).

These mechanisms and parts, and their operation, will be fully described in succeeding chapters of this pamphlet. The keyed illustrations shown here, however, should be studied carefully, as an aid in locating the different mechanisms while studying the following pages.