Maintaining, in good working order, mechanisms such as those described in this pamphlet, depends entirely upon the skill and zeal of the operating personnel, and upon their detailed and thorough understanding of the construction and function of each unit in the mechanism. In view of the number of parts involved, it is considered impracticable to foresee and instruct against every malfunction or casualty which will be encountered in service. Also, in view of the varying conditions which will be met with in service, it is considered impracticable to establish lubrication or maintenance routines. In general, circumstances permitting, each working part of a submarine torpedo tube should be exercised daily, under war conditions, and lubrication and other maintenance performed as the necessity is indicated by the exercising.

The purpose in this chapter is to present certain principles that are generally applicable, and to direct attention to a few specific cases where trouble may be anticipated, based wholly upon service experience up to this time.

2. LUBRICATION

All working parts should be maintained in a clean and oily condition. Lubrication charts are included in the General Information Books supplied each vessel by the Bureau of Ships, and these should be referred to for complete information regarding the lubrication on each particular vessel. In the absence of other instructions, the inside of the barrel should be dried occasionally, and coated with a heavy mineral oil, such as 60O W (or Navy symbol 6135).

Caution: Oil electrical parts sparingly, if at all, using a very light mineral oil. Also, care must be exercised in the choice of general lubricants, since some commercial lubricants which are reasonably satisfactory for steel will corrode bronze, especially in the presence of salt and moisture. Old lubricant should be wiped off as much as practicable before

3. WEAR OR DEFORMATION

All working parts should be scrutinized at every opportunity, to detect and remedy any incipient causes of failure. For example: Tripping latch linkages, stop rods, and interlocks should be examined for deformation and lost motion, and for correspondence between actuation and response, to make certain, for instance, that when the tripping latch is raised by opening the breech door, it does not project within the 21.125 inch bore of the tube, which would cause the tripping latch to interfere with the loading of a mine; also that when it is lowered, with all lost motion taken out in the up direction, it projects within the bore by only the required amount as shown on the drawings which are applicable to the specific vessel. The gage supplied in the tool kit (M in Figure 229) may be used for this purpose.

Also, when a stop bolt is down, and with all lost motion taken out in the up direction, its lower face should be at the height prescribed by the applicable drawings and as checked, if practicable, by the barrel center line gage.

4. ADJUSTMENTS

Before undertaking to adjust any mechanism on a torpedo tube, reference should be made to the applicable drawings. The chances are that if one mechanism is adjusted differently than shown on the drawings, possibly in an effort to improve its operation, it will be found that it is rendered unsafe in some other respect, or that the operation of some other related mechanism has been impaired. Where this appears to be definitely not so, the Bureau of Ordnance should be notified at the earliest practicable date to facilitate appropriate decision and action.

5. STUFFING BOXES

The stuffing boxes should not be tightened more than just enough to prevent leakage. From the

6. PRESSURE GAGES

Pressure gages are particularly subject to derangement, especially when subjected to vibration or

7. GASKETS

Gaskets tend to deteriorate when held under pressure, and also when subjected to excessive temperature changes, or when exposed to moisture or oil, especially so if they contain natural rubber or some

8. VALVES

Valves should be exercised, particularly those not used in normal operations. This applies with particular force to the manually operated valves which close off the poppet valve discharge. Although no occasion may arise for the use of this valve during the life of a particular vessel, it is the ultimate safety feature in the operation of poppet valves, and should be maintained accordingly.

9. AUTOMATIC DRAIN VALVE

This valve, which will be found at the bottom of the firing and check valve body, as described on page 60, in Chapter 5, on the firing mechanism, should be exercised occasionally by hand to make certain that it is not sticking.

10. SOLENOID ACTUATED FIRING VALVE

The stop cylinder valve, described in Chapter 5, on page 51, should be exercised occasionally by hand, making certain that the interlock bar is not in the ready to fire position. At the same time, the cleanliness and operating condition of the solenoid and the firing lever should be observed, particularly since the operation of poppet valves greatly increases the likelihood of corrosion of all parts of the tube nests.

Make certain, also, that the vent holes in the stop cylinder, and in the stop cylinder head, are clear. If the former are obstructed, the firing action will be sluggish. If the latter are not clear, and the solenoid actuated valve leaks, air pressure will build up in the stop cylinder, causing the end of the stop rod to engage with the interlocking bar so that it can not be moved to the ready to fire position.

11. THE PILOT VALVE

The pilot valve, which is at the end of the stop cylinder, as described in Chapter 5, on page 52, vents the air chamber above the firing valve,

permitting the firing valve to open so as to fire a torpedo. If properly seated, the pilot valve is best left alone, except during overhauls. Leakage of this valve may cause the firing valve to flutter on its seat, or possibly even to open entirely. If any water used to prime the firing valve is blown over by firing, that fact should be evident, after firing, by an examination of the pocket in the stop piston housing into which this pilot valve vents.

Figure 233 Roller parts disassembled. (A) Bracket; (B) Roller; (C) Shims; (D) Roller pin; (E) Screws for roller pin.

12. BARREL ROLLERS

There are four rollers fitted on the under side of the tube, these rollers supporting the torpedo while it is in the tube. These rollers facilitate the movement of the torpedo as it passes through the tube, and case the effort of loading. In addition, they furnish a means whereby the position of the torpedo in the tube may be adjusted very slightly. In general, they should be set to project about .03 inch within the tube. When the rollers are in

this position, the torpedo should be approximately centered in the tube, there should be no binding or scraping during the loading, of a torpedo, and the depth, gyro, and speed setting spindles should engage and disengage in the sockets of the torpedo readily.

Adjustment of the rollers is obtained by shimming under the ends of the roller axle pin in each roller bracket. When removing any roller, note should be made of the thickness of the shims under each end

The roller pocket nearest the breech of each tube is fitted for the entry of an electrical heating cable. Several different types of such fittings have been installed. The type now regarded as standard is shown on Figure 234. An earlier type is indicated on Figures 230, 231 and 232.

13. TAIL STOP

The tail stop provides a means for holding the torpedo against the stop bolt in order to prevent any motion of the torpedo that might otherwise occur due to inclinations, sudden shock, and so on. If the stop plate has been fitted with a rubber pad or gasket to beat against the propeller nut of a torpedo, the tail stop should be screwed home quite firmly, since one purpose of the rubber gasket is to minimize the surging of water into and out of the tail cone of a torpedo such as may occur in an upper tube while running on the surface with muzzle doors open.

If the stop plate has not been fitted with the rubber pad or gasket, the tail stop should be screwed up hard and then backed off about one-eighth of a turn, as described on page 27 (see Figures 31 and 32), so as to avoid putting a load on the stop bolt which might cause sluggish action.

In order to use a torpedo tube testing set, as described in the preceding chapter, in the section covering test procedures, it is necessary, if a rubber pad is installed on the stop plate, to remove all metal parts which secure the pad, that is, referring to Figure 31, the long securing stud with its outer nut (standard form) and its inner nut (conical) and the brass washer under the conical nut. If the rubber pad adheres tightly to the stop plate where it has been cemented, it may be left in place. If not, remove it. If no rubber pad is fitted, the three-eighths inch iron pipe size plug which in that case closes the hole in the hollow stop spindle must be removed. In either

14. FIRING VALVE

Proper ejection of a torpedo is dependent upon the attainment of a proper tube pressure, which should be neither too high nor too low, and this, in turn, depends entirely upon the automatic operation of the firing valve. The rate of opening of the firing valve is regulated by the throttled flow of a definite quantity of water, the quantity of water which is contained within the cupped portion of the valve below the skirt of the upper head the throttling orifice being the small circumferential clearance between the outside diameter of the valve plate and the inside diameter of the skirt of the upper head (see Figure 104, page 55). The following conditions would cause the valve to fail to lift so as to properly regulate the tube pressure:

(a) Improper diameter of the outside of the valve plate or the inside of the upper head skirt. If the throttling area is too small, the valve will lift sluggishly and the tube pressure will be too low for proper ejection of the torpedo. If it is too large, the valve will lift too quickly and the maximum tube pressure will be too high.

The clearance between the outside diameter of the valve plate and the inside diameter of the upper head skirt is very critical. At the most, it amounts to only a few thousandths of an inch. Once established, it should not be altered. When it is necessary to remove corrosion from either part, it should, preferably, be chucked in a lathe, rotated at slow speed, and a very fine abrasive applied cautiously, as by a polishing cloth. It should be remembered that, although a slow and painstaking procedure is onerous, if this clearance once becomes too great the only remedy lies in replacing one or both of the parts, followed by a complete calibration check by the trial firing of torpedoes or dummies.

An operating check of the valve may be made

(b) By the use of a gasket between the valve body and the upper head which is not of uniform thickness or hardness, or by failing to screw down the upper head bolts uniformly, the upper head can be "cocked" so as to bind the valve and prevent it from opening properly, resulting in a tube pressure that is too low.

(c) The presence of an air bubble in the space within the valve and below the upper head skirt, which is supposed to be filled with water, will cause the valve to start opening too rapidly, and this will result in the tube pressure building up suddenly to a pressure greater than desirable. If the valve has been properly primed, such a bubble could not exist except by reason of the failure of some of the air initially present under the skirt of the upper head, within the valve, to rise out of that chamber at the time of filling. Due to the narrowness of the opening, this could be caused by the presence of grease or other foreign matter around the edge of the valve plate. The proper method of exercising a firing valve so as to insure the absence of an air bubble, and so as to detect any binding which might exist, is described in the special note following paragraph 3 (b) (5) of the section on Operating and Test Procedures, Chapter 11, on page 126.

15. DRAIN GRIDS

Drain grids should be kept clear. If zincs are fitted in any of the drain pockets, they should be renewed immediately as they become expended.

16. BREECH DOOR LOCKING RING

The breech door locking ring should turn freely upon its threads on the breech door flange at the breech end of the barrel. These threads should be kept clean and oily. The use of abrasives should be avoided, if possible, and if used it should be made certain that no abrasive particles are allowed to remain on the parts. Before disassembling the locking ring from the flange, a mark should be made on the ring and the flange at the point where they disengage, since the threads are triple and will go together in three different positions.

From its location, the muzzle door section "of the tube is one of the most inaccessible parts for inspection. Therefore, advantage should be taken of every drydocking to inspect the gaskets, and they should be replaced on the grounds of less deterioration than that necessary to warrant the replacement of other similar, but more accessible, parts.

18. SPRINGS

All springs are subject to deterioration in service. Steel springs are likely to corrode, in spite of any plating or other preventive measures, and a small or local decrease in diameter will considerably reduce the load carrying capacity at a given length, since the deflection under a given load varies inversely as the fourth power of the wire diameter. On the other hand, springs made of most nonferrous metals have a tendency to take a permanent set when under load, as most springs are. In consequence, springs should be calibrated during overhauls whenever facilities permit, particularly if they are corroded, to see if the requirements as to loads and deflections shown on the detail drawings in each case are being met, and, if badly corroded or evidently incapable of accomplishing their intended purpose, they should be replaced without waiting for a calibration. If springs are replaced, they should be retained and calibrated later, if practicable, so that they may be available as spares if still serviceable.

19. ELECTRICAL INTERLOCK

The electrical interlock consists of a snap switch in series with the firing key. It is closed by the throwing of the interlock lever to the "Tube Ready to Fire" position, and is allowed to open, under the impulse of a spring, when the lever is moved from that position. It should be exercised occasionally in order to make certain that it is not sticking in the "closed" position.

20. ELECTRICAL CIRCUITS

Keep electrical circuits clean, dry, and free from oil, except that metallic moving parts may be lubricated sparingly on other than contact surfaces. Oil,

21. DRAINAGE SYSTEM

Metal to metal valve seats in the drainage system require only ordinary care beyond an occasional lapping, should leaks develop. Where valves seat on rubber gaskets, these should be inspected at each overhaul, and the gaskets should be replaced when marred or deteriorated.

The stuffing boxes on the drain and vent valves should be tight, and the packing in them should be replaced as necessary, using the packing specified on the applicable drawings, or that called for by the instructions of the Bureau of Ships.

The tube drain valve, which leads directly to the drain in the barrel, has on its stem an interlocking collar so placed so that when the muzzle door is unlocked the valve can not be opened (see Figures 76 and 78 on pages 42 and 43). Certain mechanical clearances are necessary, however, and these, cumulatively, plus the effect of wear, make it necessary that the drain valve operating lever be always given a full throw in each direction. Also, when necessitated by wear or deformation, parts should be readjusted or replaced to make certain that the interlock engages and disengages at the proper points.

22. TORPEDO STOP MECHANISM

Avoid any bending of the stop bolt and consequent binding of the parts of the torpedo stop mechanism. Careless loading of the torpedo into the barrel is the usual cause, and particular care should be taken to bring the torpedo against the stop bolt gently. A bent or otherwise mutilated stop bolt should be replaced promptly. The stop rod spring, and the stop bolt spring mounted in the recess in the top of the stop bolt, should exert the designed pressure on the stop rod and the stop bolt, respectively, and the stop bolt should slide freely in its

The clearance between the rounded end of the stop bolt lever and the top of the slot in the stop bolt should be approximately five-sixteenths of an inch. This comparatively large clearance is provided in order to prevent accidental release of the torpedo by lifting of the stop bolt if an attempt is made to fire the tube, or if pressure should leak from the ship's service line and build up in the stop cylinder, while the interlocking shutter is in the "safe" position, blocking the travel of the stop rod, the amount of travel permitted the stop rod under these conditions being insufficient to take up the clearance mentioned.

Before loading a torpedo into the tube, sight through the barrel to see that the stop bolt projects into the guide slot of the tube the full distance. When fully down, the lower end of the stop bolt should be flush with the bore of the tube. Failure of the stop bolt to occupy its proper position when the torpedo is loaded will permit the torpedo to move too far forward in the tube, tripping the starting lever, and probably striking and damaging the muzzle door.

A threaded adjustment is provided between the gyro setting retraction slide and the stop connecting rod (see Figure 212, page 114). By means of this adjustment, the "free lift" of the stop bolt may be held within the limit of 0.06 inch specified above. It sometimes happens that the stuffing box gland is taken up so tightly as to prevent the stop rod from making its stroke properly. Look for this after tests of compartments. The stop rod should make its stroke with a pressure of 100 pounds per square inch on the ship's service line, the normal pressure being 200 pounds per square inch.

"DO NOT OPEN THE BREECH DOOR of the tube without first making sure that the depth, speed and gyro setting spindles are withdrawn. These spindles are designed to take only the torque which is necessary to make the settings in the torpedo. In addition, they are mounted so as to have a certain amount of freedom in all directions, so that they will engage the sockets of a torpedo even though these sockets do not line up exactly with the tube units. Hence the spindles cannot be relied upon to retain a torpedo in place in a torpedo tube, and if they are engaged while the breech door is open and the torpedo is given any perceptible impulse to the rear, they will only be bent, without noticeably preventing movement of the torpedo."

24. POWER-OPERATED MUZZLE DOORS

It will be observed that operating the door by hand is certain to put the jack nut "out of step" for power operation, and that it is necessary, after operating the muzzle door by hand and before reverting to power operation to:

(1) Make certain that the door is either tightly

(2) Rotate the hand crank until the jack nut matches with the proper one of the two projections D on Figure 64, that is, with the breech ward projection if the door is closed or with the muzzleward projection if the door is open.

As this pamphlet goes to press, there has been authorized an additional interlock (for new construction) consisting of a bolt which is thrown by a linkage from the firing interlock lever (see Plate 3). This bolt, when the door is fully open, will pass to the rear of the muzzle door operating shaft (permitting the firing interlock lever to be placed in the tube ready to fire position). When so placed, the bolt will (up to the limit of its strength) prevent the closing of the muzzle door.

Where this last interlock has not been installed, there is a possibility that the muzzle door will not remain fully open in the event of the failure of hydraulic power after the door has been opened by power. To prevent such partial closing of the door, it is only necessary to go through the motions of opening the door by hand. This will bring the jack nut on the operating shaft against the after projection of the operating shaft bracket, where it will act as a stop collar.

1. d, u, w, kk, yy; 2. r(Seventh Fleet); 3.mm*; 3.(5 copies), pp; 4.mm; 4. (5 copies), pp; 7. g, h, 1*; 7. (5 copies), b(New Orleans, Navy No. 1995), q; 7.(10 copies), a(M.I., Phila., Portsmouth, Washington,