... the Loading End of the Torpedo Tube

On the inner surface of the breech door (Figure 22) is an annular or ringlike groove in which is set a rubber gasket which, when the door is closed and locked, presses against a bead on the end of the barrel, making the door water tight.

The breech door is held against the barrel by a locking ring (see Figure 23), an annular or ring shaped casting, having acme threads on its inner surface which engage similar threads on the end of

the barrel. On its inner surface are eight lugs, corresponding to the eight lugs on the outer surface of the door. In closing the door, the lugs on the door pass through the open spaces between the lugs on the locking ring; the locking ring is then rotated, bringing the eight lugs on the locking ring to bear against the eight lugs on the door, thereby pressing

A hinge bracket, bolted to the outboard side of the barrel at the breech end, carries the door, also the pinion gearing (Figure 24) which rotates the locking ring. The pinion shaft (Figure 25) has a squared extension to which is attached the operating handle. As the handle is turned, the action of the pinion on the gear segment attached to the side of the locking ring causes the locking ring to rotate (see Figures 26, 27, 28, 29).

Figures 24 Figure 24 (left) - Gearing which rotates breech door locking ring. Callouts show the Pinion Gear, Squared extension for handle and Gear segment on locking ring.
Figure 25 (right) Pinion gear segment on locking ring.

The locking ring carries a lug which engages an interlocking bolt connected with the interlocking mechanism described in a later chapter. When this interlocking bolt is raised it clears the lug and permits rotation of the locking ring for opening the breech door. When the bolt is lowered, it prevents rotation of the locking ring.

Mounted in the upper arm of the breech door is a key (see Figure 30) which causes the tripping latch cam to rotate when the door is being opened or closed. This cam actuates a lever connected with the operating shaft which leads to the tripping latch. The tripping latch, as explained in a later chapter, trips the starting lever on the torpedo as it is leaving the barrel. Opening the breech door raises the trip ping latch to permit loading a torpedo into the tube

Figure 30 (A) Tripping latch cam; (B) Key on upper arm of breech door engaging cam.

without interference. Closing the door lowers the latch into position to strike the starting lever of the torpedo when it has moved about three-fourths of an inch forward from its normal loaded position.

A reflex water gage, in two sections, is mounted on the breech door, also a pressure gage to indicate tube pressures. The pressure gage piping is provided with a check valve (against the gage), the purpose of which is to retain the indication of the maximum pressure, attained when firing, long enough to be read. In earlier vessels, the passages from the inside of the tube to the chambers of the reflex gage were cored to an area of about one-half square inch. Since this area was considered

unnecessarily large, the size of these holes has been reduced to one-fourth inch diameter, by the use of bushings, to reduce the amount of water that might enter the submarine if a reflex gage glass were to break.

In loading a torpedo into the tube, the tail stop is retracted by turning the tail stop handle to the left two full turns, thereby preventing interference with the torpedo or jamming it against the stop bolt when closing the breech door. After the breech door is closed, the tail stop handle is turned to the right so the tail stop is tight against the propeller nut on the torpedo. Then, unless the tail stop is fitted with a rubber disc to bear against the torpedo propeller nut, the tail stop is backed off by turning the handle to the left about one-tenth of a turn to prevent binding the torpedo against the stop bolt.

When a torpedo tube test set is used, it is secured by the pipe tap in the outer end of the tail stop spindle. If a rubber buffing disc is fitted on the tail stop, its retaining stud and nuts must first be removed.

All operating parts and mechanisms of the torpedo tube are controlled by an interlocking system, described later in this pamphlet. Hence, opening and closing the breech door also operates mechanisms connected with the muzzle door operation.

To open the breech door, it must first be made certain that the muzzle door is closed, and that all water which entered the tube during the previous firing is drained off. With this positively assured, the breech and muzzle door interlocking lever, located at the side and just over the breech end of the barrel, is moved to Breech Door Unlocked position on

Figure 33 Turning breech door locking ring; A Operating handle turning locking ring; B Pinion gear engaging gear segment on locking ring; C Lugs on locking ring engaging lugs on breech door

A word of caution: The door must be held by hand until it is fully open and bears against the stops on the bracket. Jerking the door open and allowing it to swing under its own momentum to an abrupt stop may damage the mechanism and prevent water tightness when the door is closed.

Figure 34 Breech door locking ring turned, door unlocked, lugs on door disengaged, door ready to open.

Muzzle doors were designed for manual operation only on all torpedo tubes in: SS 198-242, 247-251, 253-274, 281 and 282, and on stern tubes in SS 243, 246 and 252. The text which follows, down to the heading "Power Operation" on page 32, describes this manually operated mechanism. The balance of this chapter deals with the mechanisms designed primarily for power operation, with manual operation retained only for emergency use, which are installed on all other torpedo tubes in submarines subsequent to SS198.

The Muzzle Door Mechanism consists of the door itself (Figure 35); a bracket; a door arm; a worm and worm segment (Figures 36 and 37); a breech bracket, located over the breech end of the tube; an operating shaft (see Figures 42, 43, 44); a muzzle door indicator (see Figure 44), and interlocking features which are described in Chapter 4.

The muzzle door, like the breech door, is a bowl shaped bronze casting. In a groove around the inner surface of the door is set a rubber gasket, the same as on the breech door, which, when the muzzle door is closed and locked, is pressed against a V-shaped beading around the end of the barrel (Figure 35), forming a water tight seal.

Figure 36 Gearing for opening and closing manually operated muzzle door, barrel rolled on side to show gearing. (A) Operating shaft; (B) Worm segment; (C) Worm which operates worm segment to open or close door.

Figure 35 Muzzle door, open at 45 degrees. (A) Annular groove containing rubber gaskets; (B) V-shaped beading around end of barrel; (C) Rubbing strip; (D) Connections for shutter door arms; (E) Operating shaft connection (this being for power operated muzzle door).

Figure 37 Showing worm and worm segment in muzzle door open position.

Muzzle doors and their operating mechanisms for stern tubes are similar in general design and operation to those for bow tubes. Differences arise, principally, from the omission of shutters in some vessels. Where this is done, it sometimes has been possible to obtain operating advantages by hinging the doors on other than vertical axes. Reference must be made to the plans or drawings known to be applicable to a particular vessel or class of vessels. Every submarine carries a set of the drawings or blueprints which apply specifically to it.

The muzzle door and shutter are opened and closed by means of the operating shaft, which extends from the muzzle door to the breech bracket at the breech end of the tube, this shaft being fitted with appropriate stuffing boxes, couplings, and universal joints as necessary.

All operating mechanism and controls for the muzzle door are located at the breech end of the tube and, as stated in previous references to the breech door, both the breech door and the muzzle door are linked together by the interlocking mechanism so that one can not be opened until the other is closed and locked.

The muzzle doors of bow tubes open out into chambers at either side of the submarine, and these chambers are equipped with shutters (see Figures 40 and 41 for the type installed in submarines under construction as this pamphlet is issued) which are opened and closed as the muzzle door is opened

Figure 40 Outboard view showing muzzle door with shutters open.

Figure 39 Closing muzzle door by hand (action to right).

and closed, a shutter arm being connected to the door arm on the muzzle door (see D in Figure 35). The closing of the shutters when the torpedo tube is not in action eliminates the resistance that would be created by water entering the chambers

Figure 41 Outboard view showing shutters for muzzle doors closed.

The forward ends of the shutters shown by Figures 40 and 41 are fitted with vertical pins upon which rollers are mounted. Grooves for these rollers are provided in the horizontal plating above and below each shutter, so that as the rear of the shutter is thrown in or out by the shutter arm of the door mechanism (to open or close the shutter as the muzzle door is opened or closed) the forward end of the shutter slides to the front or rear, sliding behind the hull plating forward as the shutter is opened.

In certain submarines other types of shutters will be found. For instance:

(1) A type similar in all respects to that pictured by Figures 40 and 41 except for being curved around a horizontal axis, and

(2) A type which is hinged at the front end instead of having the front end slide on rollers. On this type, the pin at the end of the shutter arm engages a slot in the shutter-frame instead of a hole. Due to the lost motion which develops with this type of linkage, such shutters have a special locking mechanism to hold them open, so that they will not foul a torpedo.

The interlocking mechanism which controls the opening and closing of both the breech and the muzzle doors is fully described in the following chapter of this pamphlet. Briefly, however, the operation of this mechanism as it applies to the muzzle door is as follows:

Located on the breech bracket at the breech end of the tube is a system of levers and indicators, as shown in Figure 44. As the breech and muzzle door interlock lever is moved from one position to the other, it engages or disengages bolts in the cylinder slide which moves in the breech bracket (see Figures 42 and 43), thereby locking or releasing the muzzle door operating shaft. To open the muzzle door, the breech and muzzle door interlocking lever is moved to the "Muzzle Door Unlocked" position on the indicator plate. This can not be done, however, until the breech door has been closed and

This counter-clockwise turning of the muzzle door operating handle operates the worm and worm wheel in the muzzle door bracket and opens the

To close the muzzle door, the sequence of operation is reversed. The firing interlock lever is moved to the "Muzzle Door Unlocked" position, opening the interlock switch and unlocking the door. The muzzle door operating handle may now be rotated in a clockwise direction (to the right) as shown in Figure 39, closing the door. When the muzzle door indicator pointer is at 0 degrees the door is closed, and the breech door locking bolt may be thrown, unlocking the locking ring on the breech door.

Figure 46 Control valve operating handle for power operation of muzzle door handle in door open position.

Figure 47 Handle in muzzle door closed position -left.
Figure 48 Handle set for opening door by hand - right.

The cylinder slide has slots which engage the interlock bolts for the breech and muzzle door and drain valve and muzzle door interlocks, the same as with manual operation, so the thrust rod cannot be operated unless these interlock bolts are in correct position.

The muzzleward end of the thrust rod is connected to the control valve by an arm (Figure 52). When the control valve handle is in closed position, the arm is toward the muzzle door (Figure 52); when in open position, the arm is toward the breech door (Figure 53); when in neutral for hand operation, the arm is in the center (Figure 54).

Figure 53 left - Figure 54 right

Figure 55 left - Figure 56 right
Figure 55 Control valve opened to show interior (view taken from back of valve as shown in Figures 52, 53, and 54), with piston in position for muzzle door closed. Position for muzzle door open shown in Figure 56; neutral position for operating by hand in Figure 57; interior with piston removed in Figure 58.

Figure 57 left - Figure 58 right

Cut-away views of the valve are shown, Figure 55 being with the piston in muzzle door closed position (hydraulic pressure being on the muzzleward end of the operating cylinder); Figure 56, muzzle door open (hydraulic pressure being on the breechward end of the operating cylinder); Figure 57, neutral for hand operation (hydraulic pressure being blanked off from both ends of the operating

Figure 61 Operating rod and packing for power cylinder. (A) Shaft; (B) Retaining ring; (C) Piston cup (leather); (D) Piston; (E) Piston cup (leather), (F) Retaining ring; (G) Machine screws for fastening retaining rings to piston.

Figure 62 Breech end of muzzle door operating shaft. (A) Threads on shaft which engage gear (B) for operating interlock chain; (C) lack nut gear engaged by long spur gear on hand operating shaft; (D) Threads on operating shaft engaged by jack nut gear; (E) Gear; (F) Sprockets.

As the operating shaft is moved by the power cylinder, teeth on the breech end of the shaft engage gearing (Figure 62) operating the interlock chain, which is connected at the top with gearing engaging teeth on the under side of the interlock sleeve operating shaft. As the muzzle door opens or closes, the interlock sleeve operating shaft and the cylinder slide move, rotating the pointer on the muzzle door indicator.

Provision also is made for opening and closing the power operated muzzle door by hand should it become necessary. A hand operating shaft is provided (Figures 63 and 64). At the end of this shaft is a long spur gear which engages a jack nut on the muzzle door operating shaft (Figure 64), the jack nut having teeth parallel with the shaft on its outer surface and a screw thread on its inner surface to engage the thread on the power shaft. When the

The hand operating shaft is acted upon by special interlocking mechanism so as to obtain the same results as in power operation. This mechanism consists of rods extending down from the interlock levers (Figure 45) to, dogs which appropriately engage or release a gear on the hand operating shaft (in Figures 65, 66 and 67).

For further information, consult section 24 of Chapter 12.