The tripping latch is a hammer-shaped lever, about six inches long and five-eighths of an inch thick. It is so arranged and placed that it engages the torpedo starting lever when the torpedo has moved forward three-fourths of an inch after the firing charge has started it out of the tube.

When a torpedo is being loaded into the tube, the tripping latch must be raised, or retracted, from the barrel, so there will be no interference with the

Figure 199 The breech door hinge bracket, showing the tripping latch am. (A) Tripping latch arm, which connects with operating shaft as shown in Figures 200 and 201; (B) Roller; (C) Tripping latch cam; (D) Key which rotates cam when engaged by (E) Free end of upper arm of breech door.

However, the mechanism is so designed that the tripping latch is raised out of the tube as the breech door is being opened, and it is lowered back into position as the breech door is being closed. This is done by means of a cam attached to the upper hinge pin of the breech door, a key on the cam being engaged by the end of the upper arm of the breech door as it is being opened, thereby rotating the cam, as illustrated and described in Chapter 3 (see especially Figures 24 to 30, on pages 26 and 27). The cam is also shown here in Figure 199.

Figure 200 shows the linkage between the cam on the breech door, the operating shaft, and the tripping latch housing, in the position when the breech door is closed. Figure 201 shows the linkage in the position when the breech door is open. Another view of the tripping latch housing and the linkage with the breech door is shown in Figure 202, this illustrating the position of the tripping latch housing with relation to the poppet valve and other operating units.

An interior view of the tripping latch housing is shown in Figure 203, illustrating the latch lowered into the barrel to contact and trip the torpedo starting lever.

The curvature of the cam, shown in Figure 199, is such that the tripping latch is in the extreme down position before the breech door is entirely closed. Hence, this position of the tripping latch can be verified by sighting into the barrel before fully closing the breech door. During the opening of the breech door, the tripping latch cam remains in neutral position for the first 45 degrees of the opening of the door, so that the latch can also be observed by sighting down the barrel as the door is being

The starting lever on the torpedo, which is engaged by the tripping latch to open the torpedo starting valve and set the operating mechanism in the torpedo in action, is shown in Figure 204. Here, the operator is removing a safety stick from the starting lever preparatory to loading the torpedo into the tube. This safety stick is inserted to protect the starting lever, and to prevent it from being tripped unintentionally or accidentally while the torpedo is being handled up to the time of loading into a torpedo tube.

There are certain differences between the tripping latch as installed on some of the earlier submarines and those on vessels of more recent construction. This is due to the fact that the somewhat limited movement of the tripping latch in the original design was found, after moderate wear, to be insufficient to insure proper adjustment by means of the turnbuckle arrangement provided, so as to permit the latch to project the required amount within the bore when down but with all lost motion taken out

This last condition has no effect in connection with torpedoes, as the slope of a war or exercise head on a torpedo will push the latch up out of the way. It is likely to cause interference, however, when mines are being loaded into the tube.

In some installations, therefore, a crank arm, having provision for adjusting its length, will be found substituted for one of the crank arms of the earlier design. In some other installations, especially those of later construction, the throw of the tripping latch has been increased by changing the relative lengths of crank arms, without altering the operating cam, so as to allow for the development of a considerable amount of lost motion due to manufacturing tolerances and service wear, without resulting in any objectionable projection of the tripping latch within the bore when up.

It will be noticed, particularly in Figures 202 and 203, that a turnbuckle attachment is connected in the link leading directly from the tripping latch housing to the operating shaft. This turnbuckle attachment is provided for the purpose of adjusting

Figure 203 The tripping latch housing, interior view, showing tripping latch extending down info the tube in position to trip starting lever on torpedo. Dotted lines show position of latch when raised.

the tripping latch as required.

Tripping latch linkages should be examined carefully at regular intervals to make certain that there is no deformation of any of the parts, also that there is no lost motion in operation. These linkages should also be tested carefully for correspondence between actuation and response, to make certain, for example, that when the tripping latch is raised by the opening of the breech door it does not project within the 21.125 inch bore of the tube, in which case it would interfere with the loading of a mine, as previously stated; also, that when the tripping latch is lowered by the closing of the breech door, it projects into the tube the required amount as shown by the drawings which apply specifically to the particular installation in the submarine.

Figure 204 The starting lever on the torpedo, operator removing safety stick which protects the starting lever and prevents it from being tripped accidentally up to the time the torpedo is loaded into the tube.

On the top of the torpedo is a guide stud which slides in the guide slot in the top land of the interior of the barrel, keeping the torpedo in its proper position and preventing it from rotating in the tube. The torpedo stop bolt engages this guide stud as the torpedo is being slid into the tube.

The stop bolt housing, detached from the tube, is shown in Figure 205, a side view being shown in Figure 206. In Figure 207, a view of the under side of the housing, the stop bolt is shown in the down position, while in Figure 208 the stop bolt is shown in the up position. Figure 209, in which the housing has been broken away, shows the interior mechanism and its operation. Figure 210 is a view of the parts disassembled.

Each of the two housings includes the stop bolt lever, the stop shaft, and the lever attached to the stop rod which lifts or retracts the stop bolt at the time-of-firing. Only one stop bolt, stop bolt gib, and stop spring are installed, however, these parts being interchangeable from one housing to the other.

Referring to Figure 207, the stop bolt, as well as the stop bolt gib, and the stop spring, can easily be removed from the stop bolt lever and the housing by simply removing the gib screw. Care should be taken to observe the position of these pieces as they are removed, so they can be placed in the other housing in the same order and without difficulty, the procedure for assembling these parts, or for putting them in the housing, being the reverse of that for removing them.

The stop bolt is lifted or retracted from the tube by means of the stop rod, which is connected with the lever (A in Figure 207). The stop rod extends, through a stuffing box, to the retraction slide (by means of which the stop piston retracts the gyro setting spindle) which in turn is connected to the piston of the torpedo stop cylinder (as in Figure 211, which forms a part of the firing

Figure 205 The torpedo stop bolt housing.

Figure 207 Torpedo stop bolt housing as seen from underneath, showing (A) Lever to which stop rod is attached; (B) Stop bolt, in down position; (C) Stop bolt gib; (D) Gib screw; (E) Stop shaft; (F) Stop bolt lever.

Figure 208 Showing stop bolt in up position.

As the stop rod is drawn toward the breech end of the tube it pulls the lever (A in Figure 207), which is attached to the stop shaft (N in Figure 210). This stop shaft enters the stop bolt housing through a stuffing box, which must be kept tight to prevent leakage, yet not so tight that it will prevent rotation of the shaft and thereby interfere with the proper operation of the stop bolt.

Figure 209, which shows the interior of the housing, gives a better idea of the operation of the stop bolt. Studying this with Figure 210, which shows the parts disassembled, the following steps should be noted: The stop shaft connects with the stop bolt lever (Q in Figure 210), the rounded projection at the end of this lever engaging a slot in the stop bolt (V in Figure 210).

The action of the stop bolt lever, as the stop rod is pulled by the piston of the torpedo stop cylinder, raises the stop bolt vertically, the stop bolt gib (S in Figure 210) and the shape of the housing acting as a guide for the vertical movement of the stop bolt. A lug on the stop bolt gib determines the position of the bolt when it is down.

The length of the slot in the stop bolt which is engaged by the rounded end of the stop bolt lever permits a slight overtravel of the top rod. This feature is carried over from the tube design as it existed before the adoption of automatic gyro setting spindle retraction. The overtravel was originally provided so as to allow the stop rod to make a portion of its stroke without lifting the stop bolt, in case air pressure should, by leakage or malfunction, come on the stop cylinder while the firing interlock shutter bar is in position to block the stop

The stop bolt has three grooves, two of which extend the entire length of the bolt. The purpose of these grooves is to allow free passage of air and water from the barrel, and thereby prevent any obstruction to the upward movement of the stop bolt which might be caused by air and water be coming trapped in the upper part of the housing.

It is important that the connections between the stop rod and the lever which operates the stop shaft to raise the stop bolt be carefully inspected regularly, and that it be maintained in proper adjustment at all times. An adjustment spacer is provided for adjusting the stop bolt lever, this spacer being located

When loading a torpedo into the tube, extreme care should be taken to ease the torpedo gently against the stop bolt to avoid bending the stop bolt or binding any of the parts of the stop bolt assembly. Should the stop bolt become bent, or in any way mutilated so it does not function properly, it should be immediately replaced.