1. Upon retrieving torpedo, pass nose line through nose piece. Pass prepared tail line over nose line and allow to slide aft on torpedo.

2. Kick boat ahead taking strain on nose line-secure tail line as soon as torpedo is horizontal and close aboard.

3. Close stop valve.

4. Put on propeller lock.

5. Proceed to firing vessel or tender as per instructions.

6. Once aboard place on horizontal chocks right side up, and remove all handhole plates on battery compartment. If acid has been spilled, neutralize and flush out battery compartment at once.

CAUTION.-While servicing torpedo, with battery in place, do not invert as acid may be spilled.

7. Open hand-operated switch in power line to motor.

8. Put on starting lever lock.

9. Wipe torpedo exterior clean and dry.

10. Remove drain plug in afterbody and drain. Measure how much water has leaked into afterbody and record in book.

11. Remove replacement screw of depth mechanism.

12. Record depth setting on torpedo and reset to zero.

13. Put in transportation pin and secure.

14. Remove gyro clamp plate and gasket.

15. It is important that readings be taken of battery voltage and specific gravity as soon as possible after recovery. Test total voltage of 80 cells by placing meter leads at battery after terminals. Test specific gravity of several pilot cells.

16. Repeat these readings one-half hour after the first reading. Record all readings in record book.

17. Remove gyro bottom head.

18. Remove gyro, wipe pot dry, clean and oil top and bottom bearings, replace bottom head and clamp plate, over gasket.

19. NOTE.-If gyro pot has been flooded, or if gyro is wet, submerge in gasoline or spirits, and blow dry. Disassemble without changing adjustments; oil thoroughly and reassemble.

20. Record gyro angle as indicated in gyro pot, to check gyro-setting device, and obtain data for record book:

Disassemble, Oil, and Reassemble Tail.

21. Remove after propeller lock nut and lock screws.
22. Remove after propeller lock nut.
23. Remove after propeller.
24. Remove four keys.
25. Remove forward propeller lock nut lock screws.
26. Remove forward propeller lock nut.
27. Remove forward propeller.
28. Remove four keys.
29. Remove gyro and depth rudder rod pins.
30. Remove the two forward screws holding each vane to afterbody.


31. Remove terminal cap from heater flange in afterbody, remove leads from heater flange.
32. Remove 12 screws at tail joint, and remove tail from afterbody. Be careful not to drop washers in idler gear assembly.
33. Remove two retaining plugs holding idler gear assembly in tail cone.
34. Remove idler gear assembly from tail cone.

Idler Gear Disassembly.

35. Remove bearing cups, Oilite and steel thrust washers.
36. Remove idler gears from crosshead shafts.
37. Examine very carefully the bushing inside the gears, all Oilite and steel thrust washers, and the crosshead shafts for excessive wear. Examine the bearing in the bore of the crosshead. See that the lubrication hole in the center is still clear. Grease all moving bearing surfaces carefully, after thoroughly drying all parts.

Forward Propeller Shaft.

38. Remove from tail.
39. Examine the gear teeth, and the bearings in the after end, and inside the gear.
40. Dry all moving surfaces, and thoroughly grease.
41. See that keys are in good condition.

After Tail Bulkhead.

42. Examine the bearing-oil and dry thoroughly.

Examination of Afterbody Bulkhead.

43. Disconnect rudder rods from steering engines.
44. Pull on rudder rods-should take 6 pounds to move them. If not, remove the packing gland nuts, repack, and replace the nuts. (See section on Afterbody Bulkhead, ch. 5.)
45. Remove 12 bulkhead screws.
46. Remove bulkhead and gasket and main shaft assembly.
47. Remove drive gear lock nut.
48. Remove bevel drive gear.
49. Remove steel and Oilite washers.
50. Pull shaft out of bulkhead bearing.
51. Examine seat ring where sylphon rides on shaft collar.
52. Examine inside shaft bearing in bulkhead.
53. Grease all bearing surfaces.

Remove Exercise Head.

54. Remove plug and drain into bucket. Measure amount of water remaining in head.
55. Remove joint screws. And remove exercise head.
56. Disconnect air lead.
57. Note condition of gasket.
58. Remove depth and roll recorder.
59. Remove torch pot or flashlight if used. Disassemble flashlight. Note if case was watertight. Dry all parts thoroughly and replace piece of fiber between switch points.
60. Try discharge valve to see that it works easily. Remove cover plate, valve spring, and valve. Inspect parts, wash in spirits, dry and lubricate, reassemble and replace.
61. Flush head with fresh water. Drain, and dry with air.


62. Remove check valve from bulkhead. Disassemble, clean, oil, and reassemble. Install correctly with inlet marked "Aft" in after position. Attach outside source of air and blow through valve to insure operation.
63. Reassemble exercise head. Replace protecting ring.

Care of Batteries.

64. Note first if battery compartment is dry. If it has remained dry during run, it is possible to recharge batteries without removing them from the battery compartment. However, if water has leaked into battery compartment, it is advisable to remove batteries before charging.
65. In case batteries must be removed, remove leads to motor at battery terminals and remove heater and control circuit leads.
66. Proceed to remove battery holding bolts, wing nuts, and wood spacers. (See section on Removing Batteries, ch. 4.)
67. Wash battery compartment with fresh water, and dry.
68. Inspect condition of rubber bags, battery cases, connector leads, and vent plugs.
69. After drying batteries carefully, proceed to charge as per instructions, after first noting and recording gravity of pilot cells and voltage of 80 cells in series. (It is also good practice to remove deposited salt by wiping batteries freely with rag soaked in fresh water, before drying.)
70. If battery compartment has been flooded, refer to procedure on "Charging batteries flooded with salt water."
71. After charging, replace batteries in battery compartment and connect motor leads, heater and control circuit leads. If it is not desired to keep the batteries heated, leave the control circuit disconnected at the battery.
72. If battery compartment was dry, charge batteries through socket connection. See procedure on "Charging Battery."

Examination and Test of Motor.

73. If the afterbody has remained dry, the motor can be put in service again without a major overhaul. However, if water has leaked into the afterbody, soaking the coils of the motor, it is good practice to disassemble the motor and thoroughly dry all parts. The motor should be returned to a tender or base where proper facilities exist for overhaul.
74. In case of a dry afterbody, the following examination will suffice.
75. Disconnect motor leads at motor terminals through handhole.
76. Disconnect air lead to exercise head at four-way valve.
77. Disconnect heater circuit from relay.
78. Remove joint screws and pull afterbody from battery compartment.
79. Examine condition of commutator bars. Clean and remove carbon.
80. Note soldered connections of coils to commutator bars. Blow dust from armature windings, using dry low-pressure air.
81. Note condition of brushes.
82. Test tension in springs (2 3/4 to 3 pounds).
83. Grease bearings of motor and governor carefully. Grease governor gears. Check meshing of gears.
84. Set rocker ring at zero position.

(a) Turn motor so that scribe marks on governor body and shaft line up (governor arms will be approximately parallel with frame).
(b) Bleed any pressure off motor control line.
(c) By hand, pull rocker ring back until it rests against pin in zero position.

85. See that armature rotates freely with slight pressure (around 3 to 4 pounds at 1-foot radius).

86. Test tension to move rocker ring against spring (13 to 14 pounds on 7-inch radius).

87. Examine insulation of flexible leads, connecting ring, and cables. Note 1/8-inch clearance between all current-carrying cables and ground.

88. Reconnect motor leads, air lead to four-way valve from exercise head and heater circuit wires to relay. Join afterbody to battery compartment and secure joint screws.

89. If the motor has become wet, a major overhaul is necessary. The motor must be removed from the afterbody and the armature removed from the motor frame. Both must be baked and dried in a hot dry place until all wires, coils, and parts are thoroughly dried. It is mandatory to remove salt deposit by washing first with fresh water spray followed by carbon tetrachloride to displace water. Dry after this operation. The insulation of the armature and field connected in series should be tested at this point. A standard "megger" set can be used to test insulation resistance to ground.

90. The following procedure is suggested (as outlined in section on motors):

(a) Disassembly of motor.
(b) Inspection of parts.
(c) Assembly of motor.
(d) Inspection after assembly.
(e) No-load motor test.

Additional information for no-load test.-

(a) Put a jumper capable of carrying 90 amperes across starting switch.
(b) Replace motor in afterbody after assembly and test.
(c) Connect outside source of regulated voltage to the motor terminals, with switch, variable resistance, ammeter and voltmeter in line. Leave switch open. Leave resistance full in.
(d) Check brushes, should be in "zero" position. Lubricate pallet mechanism.
(e) Close switch, apply about 10 volts. Slowly increase voltage until motor comes up to speed (1,660 r. p. m.). This is usually obtained at 24 volts. Use caution-increase voltage slowly-do not exceed 1,660 r. p. m. or motor may destroy itself.

91. Shut off source of voltage, cock four-way valve, return brushes to zero position if they have moved, and remove external circuit wires. Check lubrication of motor bearings and governor. Remove jumper across switch!

Reassembly of Afterbody Bulkhead.

92. Place shaft and sylphon assembly through bearing in bulkhead. If this assembly has to be repaired, consult section on Disassembly of Tail, chapter 10.

93. Place four washers on the shaft in the following order: steel, Oilite, steel, Oilite.

94. Place four keys on keyways.

95. Place after propeller bevel drive gear on shaft.

96. Secure bevel gear with lock nut.

97. Place gasket on bulkhead.

98. Secure rods in bulkhead-and test for proper tightness (6 pounds pull). (If repacking is necessary, see Reassembly of Afterbody Bulkhead, ch. 5.)

99. Secure bulkhead to afterbody, securing shaft in spline joint at motor.

100. If afterbody has leaked badly, bulkhead must be tested for tightness. (See description in Reassembly of Bulkhead in Afterbody.)



Forward Propeller Shaft Assembly.

101. Place shaft and gear assembly in tail bulkhead bearing until collar on shaft is tight against bearing bushing.

Idler Gear Assembly.

102. Install idler gears on crosshead.
103. Install steel, and then Oilite washers on outboard side of gears.
104. Install bearing cup over washers.
105. Put dummy shaft through forward propeller shaft.
106. Place steel, Oilite, and then steel washers (3) on dummy shaft, against drive gear of forward propeller shaft.
107. Place tail cone in vise; secure by means of protruding propeller shaft.
108. Line up letter A on the forward propeller drive gear with one of the retaining plug holes in the tail cone.
109. Install idler gear assembly in tail cone. Letter A on idler gear to line up with A on drive gear of forward propeller shaft.
110. Insert and secure two retaining plugs to make assembly secure in tail cone.
111. Turn forward propeller shaft by hand-should turn easily by hand. If not try adding more grease and running in.

Tail Cone Assembly to Afterbody.

112. Insert 0.873-inch dummy shaft through forward propeller shaft and idler gear assembly (to hold thrust washers in place).
113. Assemble tail cone to afterbody. Line up letter A on after propeller, drive gear with letter A on idler gear.

NOTE.-Idler gear sometimes has two letter A's stamped 180° apart.

114. Secure tail cone with 12 square head screws.
115. Secure two screws in each tail vane to afterbody.
116. Assemble rudder rods and rudder rod connections with connection pins-secure with cotter pins. There is no need to disassemble rudder rod connections from yoke, or to change adjustment on turnbuckle, unless a complete overhaul is wanted, and it is intended to recheck rudder throws as in the preliminary adjustment. However, it would be well to check rudders with rule to see if they have been bent.

Replace Heater Flange.

117. Secure wires to terminals in heater flange.
118. Screw terminal cap to heater flange in afterbody with four screws.

Propeller Assembly. 119. Place four keys in keyway.
120. Place forward propeller on shaft.
121. Secure lock nut on propeller shaft (left-hand thread).
122. Insert lock nut lock screws.
123. Place four keyways in after shaft.
124. Place after propeller on shaft.
125. Secure lock nut on after shaft (right-hand thread).
126. Insert lock nut lock screws.


127. Turn propellers by hand. They should cross at the 12 and 3 o'clock position. There should be no binding-and the gears should move easily.
If the torpedo is being made ready for firing immediately, proceed with the preliminary and final adjustments. If not, proceed as follows:

Remove Gyro and Control Mechanism.

CAUTION-Do not invert torpedo, acid may spill.
If afterbody has remained dry during run, it is not necessary to remove gyro and immersion mechanism housing. If, however, afterbody has become flooded, the following procedure is suggested:
128. Remove handhole plate and side setting mechanism.
129. Disconnect air leads to both steering engines.
130. Disconnect rudder rod connections to both engines.
131. Disconnect air lead to gyro spin.
132. Remove steering engines.
133. Remove holding screws to gyro housing.
134. Remove gyro clamp plate cover-lock spinning mechanism.
135. Put in lifting screws and pull out housing.
136. Blow moisture off spinning mechanism with low pressure air. Dry and oil parts. Wipe dry all parts of gyro housing and immersion mechanism, paying particular attention to pallet mechanism. Oil parts well for preservation.
137. Replace housing with gaskets and secure.
138. Connect air line to gyro spin.
139. Replace both engines; connect air lines and rudder rods.
140. Replace side-setting apparatus and handhole plates.
141. Replace gyro bottom head, clamp plate, and gasket.
142. Remove gland nut on bottom shoe of vertical vane.
143. Remove cap plate from shoe, and eight screws.
144. Remove paraffin, and outside heater circuit wires (two) from terminal block, and remove wires from gland.
145. Dry parts in shoe thoroughly-micarta terminal block, and all metal parts.
146. Connect up new heater circuit wires to terminal block, after putting them through the gland nut, washer and rubber plug, examine copper tubing and see that the soldered joints have not torn loose. Examine wires which go through tubing, and see that they are connected securely to terminal block. Examine connector.
147. Replace rubber plug, washer and gland nut.
148. Replace cap and eight screws, after filling shoe with paraffin.
149. Remove terminal cap in afterbody.
150. Examine condition of wires and connections. Dry all parts and replace terminal caps.
151. Make a test for open circuit and ground, with a standard "megger" set.

Test of Main Power Circuit.

152. Disconnect both leads to battery at battery terminals.

IMPORTANT! Check to see that leads are connected at motor terminals.
153. Close hand-operated switch but leave motor air switch open.
154. Attach one lead of "megger" set to motor frame, or battery compartment wall-be sure to make a good connection. Apply other wire alternately to each side of disconnect switch. Reading on "megger" should indicate high resistance.

155. Examine relay. See that coil and wires are dry. If not, remove relay and dry thoroughly. If coil has become soaked, treat in same way as motor coil. Test to close at about 12 volts. Replace leads on battery terminals, after opening hand switch.

156. Examine outside of torpedo shell for scratches, incurred during firing. Brush off rust and apply grease to preserve metal.

157.- Secure all handhole plates, noting the condition of gaskets.

158. Secure drain plug in afterbody.


Batteries must always be kept in a fully charged condition. If a battery is allowed to run down slowly, or is allowed to stand for some time in an uncharged condition, the plates will become "sulphated". The lead sulphate deposited on the plates will become hard and will not go back into the electrolyte. In serious cases, it will cause the plates to buckle, and it .will be difficult to charge the battery.

The batteries in the mark 18 torpedo must be recharged immediately after a run. In maintaining the batteries in a fully charged condition, a freshening charge should be given whenever the specific gravity falls below 1,250, and at least once a week-whichever occurs first. When a battery stands idle, a slight amount of discharge takes place. This is called "self-discharge." Impurities in the electrolyte (especially iron) or high temperatures, will accelerate this self-discharge. For each 15° F. above 77°, the loss due to self-discharge doubles. It is therefore evident that batteries should be kept as near 77° as possible.

Charging Procedure.

When it has been determined that the batteries should be charged, the following procedure should be followed:

1. When charging, the plus lead should be attached to the plus battery terminal (usually marked red), and the minus lead to the minus side of the battery. A variable resistance is put in the circuit, so that the current can be regulated to the desired amount. All cells are connected in series as they are in the torpedo (plus to minus to plus, etc.).

2. Close the disconnect switch, after first making sure that (1) the air stop valve is closed, (2) that the air-operated motor switch is open, (3) that there is no jumper connection across the terminals, (4) that the starting lever is forward.

3. Connect the charging circuit to a standard Navy socket connection and plug into the battery charging socket just aft of the battery compartment bulkhead. Make certain that the leads from this receptacle and plug are attached, so as to connect battery and charging source (plus to plus, minus to minus).

4. Set the variable resistance at maximum position and close the charging circuit. Slowly decrease the resistance, until the current through the battery circuit is 15 amperes. The charge is continued at this rate. A thermometer should be placed in one of the batteries, and readings of the electrolyte temperature should be taken at frequent intervals. If the temperature gets above 110° F., the charging current should be lowered, bringing the temperature down.

5. The time that it takes to charge a battery depends on the charging rate, the size and capacity of the battery, and the condition that it is in. A battery that has been allowed to stand for some time discharged, or has been allowed to run down slowly, will take a much longer time to charge than one that has been kept up to charge, or one that has been rapidly discharged and immediately recharged. If the rate of charging (current) has to be lowered to keep the temperature down, the charging time will be longer. Readings should be taken of the specific gravity and voltage at frequent intervals (with current flowing). When the voltage reading


reaches and stays constant at 2.35 volts per cell (188 volts for 80 cells), at the 15 ampere rate, the current should be lowered to 6 to 8 amperes. Continue taking voltage readings (with the current flowing in the circuit) until the voltage readings remain constant for two consecutive hourly readings: Readings should be made of the specific gravity, and should be checked against the readings on the previous charges. When a battery is up to charge, the voltage readings and specific gravity readings will remain constant on charge. Records should be kept of these readings for future charging reference. After charge is over, a fully charged battery should read 168 to 172 volts, on open circuit, and should have a specific gravity of 1.270 to 1.285.

Corrections. It is very important that the following corrections for temperature be made while charging a battery: Specific gravity correction.-Specific gravity is always measured as a ratio of the weight of a unit quantity of some substance to an equal unit volume of water. Due to the expansion of all materials with increase in temperature, a base temperature has been selected for measuring specific gravities of electrolyte. This base is 77° F. The rate of expansion of water and electrolyte are not equal; therefore, if a reading is taken at any other temperature than 77° F., a correction must be made.

Rule.-For each 3 degrees of temperature above 77° F. add one "point" to the observed specific gravity to get a true reading.


Observed reading 1.248.
Temperature, 83° F.
Correction, add 2 points.
1.250is correct reading.

For each three degrees below 77° F., subtract 1 point.


Observed reading, 1.256
Temperature, 47°F.
Correction, subtract 10 points.

This should be remembered when reading gravity readings:

(a) After a run.
(b) Before charging.
(c) During and after charge.
(d) During periodic intervals when battery is standing "idle."

Voltage correction.-The voltage as observed across the battery during charge; and with the current flowing, must be corrected for temperature. Failure to do this may lead to an overcharged battery, or one that has been undercharged. Either of these cases may result in a faulty run.

RULE.-Add 0.000221 volts per cell to the reading observed, for each degree above 77° F.




1. Never let a battery heat up above 110-115° F. If it does, during charge, lower the charging rate, and charge for a longer time. Keep the battery stored in a cool, dry, place.

2. Never allow the battery to "gas" violently. A battery will start to "gas" when it is charged to about 80 percent of capacity. If the "gassing" action is too violent, particles will be torn off the plates, and will fall to the bottom of the battery. Lower the charge rate to stop excessive "gassing."

3. Never add electrolyte stronger than 1.275-1.300 to any battery.

4. Careful attention should be paid to the level of the electrolyte. Unless some is spilled, acid electrolyte should not be lost; however water evaporates, and it is necessary sometimes to add pure water to bring the level up. Impure water speeds up self-discharge action and should not be added. The correct level of this battery is 3/8 inch above the level of the separators. Most filling devices have an automatic level adjuster, but if a simple tube is used, care must be exercised not to overfill, or flood the battery.

5. Before charging the battery, always take gravity readings of several cells. Be certain that the level is 3/8 inch above the separators. If it is not, add pure water, and bring it up to level. At end of charge, allow battery to stand one hour on open circuit to allow for gas to escape, and recheck levels.

6. When a portion of the original acid has been lost due to spilling, leakage, or repair work, it will be necessary to add acid to adjust the specific gravity. The correct procedure is as follows:

(a) Charge the battery at the correct rate with remaining electrolyte until it is gassing freely, and the voltage has come up to 2.35 volts per cell. Continue the charge until the voltage and hydrometer readings are constant for 3 hours. At this point the battery is fully charged regardless of the hydrometer reading, whether it is 1.250 or 1.285. If the specific gravity is below 1.270 or above 1.285, it should be adjusted by adding or withdrawing acid. The battery should then be charged for 2 more hours at the reduced rate (watch for excessive gassing) to thoroughly mix the acid. Test again after this charge. If still low, repeat the operation (add acid, and charge 2 hours). If too high, add water (be careful not to flood).

7. Gravity readings should be taken when the electrolyte is thoroughly mixed. Thus if you are going to add water before charging, note the gravity before adding it. Two ways of mixing the solution are: By allowing it to sit for over an hour, or by charging and allowing it to gas. Readings taken after adding liquid, and before mixing will be inaccurate.

8. Never add water to acid. It will cause a violent reaction that may seriously injure the operator. Always add acid to water.

9. Letting the battery sit uncharged in cold weather may cause it to freeze. A fully charged battery will not freeze above 92° below zero fahrenheit.

10. Keep a record of all times that water has to be added to a battery. If water is needed at too frequent intervals, it may denote overcharging of the battery. A little water added frequently, however, is better for a battery than a lot of water added infrequently. If the plates are exposed by low level of the electrolyte, they will become hard and "sulphated."

11. Keep the top of the battery dry and clean. If electrolyte is allowed to collect on the top, the battery may "flash over" and burn up.

12. If the terminals become corroded, brush them with a bristle brush, use a little baking soda or ammonia to neutralize the acid, and then wash this off with water, and dry with clean rag.


13. Be sure that the vent bags are secure, and that the rubber is in good condition. These bags must be on and secure, whenever there is any chance of tipping the battery when it is full of electrolyte, as is the case during an exercise run. Gas, caused by the exposure of the bottom part of the plates, may burst the case, unless these bags are on to relieve the pressure.

14. Be sure that the batteries are wedged securely in the cases. Avoid shock and excessive vibration.

15. Use of too high specific gravity electrolyte does not give the battery "extra power." It only attacks and weakens the grids which support the plates, and increases self-discharge, and injures plates.

16. Use of too low specific gravity electrolyte causes loss of capacity.

17. Never make the mistake of adding electrolyte to "bring a battery up to charge," though the specific gravity is a good indication of the state of charge, it is the chemical action caused by the passage of charging current that changes the plates from lead sulphate back to spongy lead and lead peroxide as they are in charged condition. Simply adding acid to a discharged battery does not charge it-you merely distort the gravity reading.

18. Never overcharge a battery. This ruins the positive plates, causes muddy, soft plates, and loss of active material.

19. If any cell becomes heated on standing, examine it for a short, or high internal discharge caused by impurities. Buckled plates, a large collection of sediment in the bottom, defective separators, or acid on the top of the battery can all cause a short circuit.

20. During charge the vent plugs should be removed and replaced with special lead plugs furnished for this purpose. After charge put the regular vent plugs back in place. The rubber bags should be put in place if an exercise run is to be made, otherwise these holes should be plugged.

21. Never let a dry battery stand with plates exposed to air as this will cause ruined negative plates. Keep vents closed tight until electrolyte is added.

How to Decommission a Battery Temporarily.

1. Charge fully first.
2. Drain it and fill with pure water.
3. Let it stand one day, drain and refill with pure water.
4. Let it stand for a few more hours, then drain it. It is then ready to be stored. Seal up vents. On putting it back into service, however, a recharge is necessary.

Use of Pilot Cells.

It is often easier to check only a few cells on a large battery system, and thereby determine the condition of the batteries. However, it must be certain that these cells are representative of all the other cells. Every fourth charge (once a month) make a record of the voltage and specific gravity of each cell. If any are too low, try charging at a low rate to bring them up. If they will not come up, look for:

1. Loose connectors.
2. Corrosion of connections.
3. Low level of electrolyte.
4. Sulphated or buckled plates.
5. Excessive sediment in the bottom.
6. Low specific gravity.
7. Excessive moisture on top of the cell.

Visual Test of Plates.

When in good condition, the positive plate in this battery should be a nut brown color, the negative a dark gray. When the plates are in poor or sulphated condition, they will appear light in color, and a crystalline substance may be observed on the surface.

How to Cure "Hard Negatives."

If these occur, and it is desired to save the battery:

Discharge the battery to zero voltage. Continue past the zero point by putting current through the battery in the direction opposite from charging (plus to minus, minus to plus). After doing this for a short time, recharge the battery. The condition of the plates will be improved. This should only be done under the supervision of a trained battery specialist, and is not suggested in most cases unless absolutely necessary.

Use of the Vent in the Battery Compartment.

A small pipe is secured to the inside of the battery compartment with its opening near the forward end. If it is desired to vent the compartment and remove any gases generated during charging, the handhole cover near the aft end of the compartment should be removed, and a low pressure air line connected to the pipe.

How to Cure Sulphated Plates.

The best method to cure sulphated plates is to charge and rapidly discharge the battery several times. On charge, allow the battery to gas for a considerable time, watching the temperature so that it will not become too high. This is the best all around cure for most battery ills.

If this treatment does not work, a method often called the "water cure" can be used.

1. Remove the electrolyte.

2. Put in pure water-allow to stand for 1 hour.

3. If it is thought that sufficient material will come out of the plates into the solution, the battery can then be charged without adding anything to the water. However, if it is felt that the plates are too sulphated for this to occur, remove the water and replace with 1.275 electrolyte. Charge for a long time at one-half the usual rate. When the specific gravity and the voltage remain constant for 10 hours, the battery is near charge. Add water or acid, to bring the gravity to the proper value, and allow to gas for some time on charge to mix the electrolyte. Then take more readings, and when the specific gravity and voltage remain constant for some time, the battery is charged.

This method is only recommended when batteries have become badly sulphated and no other batteries are available. It is strongly advised, however, that such batteries should not be used on a run, if other batteries are available, because once plates are badly sulphated, they are seldom reliable afterwards, and may give a bad performance, even though the voltage and specific gravity on charge seems to indicate they have recovered.


If the battery compartment has a few inches of sea water in it when the torpedo is recovered, there is slight possibility that sea water has gotten into the battery. However, if the compartment is completely flooded, or the torpedo has been down for some time with water in the battery compartment, there is a definite possibility that salt water may have entered the battery through the vent.


Test for Salt in Battery (Sodium Chloride).

1. Take a small sample of the electrolyte.
2. Add enough nitric acid to acidulate.
3. Add a few drops of silver nitrate solution.
4. If a curdy white precipitate forms, which is soluble in ammonium hydrate, a chlorine compound is present.

Treatment of Discharged Battery.

If a battery is in discharged condition, and it is thought that sea water may have entered through the vent, the following procedure is suggested:

1. Drain battery. Fill with water. Let stand several hours. Drain and repeat operation.

2. Fill with fresh water only. Start charge at low rate (6 to 8 amperes). Continue until the gravity and voltage remain constant for at least 4 hours. If this gravity is too low, drain, and refill with 1.275 acid. Save solution drained out.

3. Continue charge until the gravity and voltage remain constant for 4 hours.

4. If the gravity on this last operation goes above 1.285, it means that the first operation (charging with pure water) was not carried through long enough. Drain acid and replace with water first used. Continue charge until specific gravity reaches a constant maximum. If this is too low, replace with 1.275 gravity, and charge until no further rise is noted over 4 hours.

Fully Charged Battery.

If a charged battery is thought to be flooded with salt water:

1. Dump and wash with water as above.

2. Put full strength electrolyte back in battery (1.275). Charge slowly for a short time until a constant reading of gravity and voltage is obtained. If the gravity will not come up high enough (it will be "cut" slightly by the water left on the plates from the first operation), add a little acid (not stronger than 1.300) and charge some more until voltage and specific gravity are constant for 3 hours, around 1.275 or slightly over.


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The air flasks on the Mark 18 torpedo may be left in an uncharged condition, when the torpedo is stored at a base or in a tender. When a torpedo is being made ready for transfer to a combatant ship, the flasks shall be charged to working pressure. When the torpedo is being kept in the fully ready condition, the flasks shall be tested once each day.

In the Mark 18 torpedo there are three flasks with a total capacity of approximately 620-630 cubic inches of air at 2,800 pounds. Due to the small volume of the flasks, care should be exercised, so that in testing operations, pressure loss will be kept at a minimum. A small volume, high pressure gage should be used. It is also obvious that even small leaks in the flasks, valves, or piping connections, will cause a serious drop in pressure.

The following procedure is suggested for air flask maintenance:

1. On charging air flasks, be certain that the starting valve is seated (the lever should be in the forward position). A safety stick should be placed behind the lever to prevent accidental firing. Important!

2. Disconnect the manually operated switch in the power circuit to the motor, rotate clockwise all the way and turn back one-half turn.

3. Close the stop valve by turning the spindle clockwise. Leave tool on spindle.

4. Loosen charging valve plug slowly, bleeding any air that may be trapped in the line. Remove plug, and inspect washer.

5. Install wing nut charging connection, complete with pressure gage, bleed-off valve, and source of air pressure.

6. Fasten safety strap, and close bleeder connection.

7. Open stop valve (turn spindle counterclockwise) and note pressure on the gage. A record should be made of the pressures when a torpedo is being kept in the "fully ready" condition. If any torpedo shows an abnormal pressure drop in a given interval of time, a thorough check must be made to find the cause. Possible places for leaks to occur are:

(a) Small pin holes in the flasks.
(b) Loose connections.
(c) A poorly seated starting gear piston.
(d) Leaks past the threads in the stop and charge valves.
(e) Leaks caused by worn-out washers in stop and charge valves.
If the observed pressure is high enough (sufficient to allow for a certain drop on removing the charging connection) no air need be added. If not, charge to working pressure of about 3,000 pounds.

8. After test and charge, close the stop valve (turning the spindle clockwise).

9. Bleed air in the line.

10. Remove the safety strap and the charging wing nut connection.

11. Examine the washer and replace the plug in the charge valve.

12. Open the stop valve all the w ay (turning counterclockwise), and close the manually operated motor switch. (If torpedo is being kept fully ready.)

13. Test stop and charge valve for tightness by putting light torpedo oil on top of the plug and around the threads, and observing any bubbles that might occur.

NOTE.-It is most important that the motor disconnect switch be open while work is being done on the torpedo. If it should be closed and the air operated switch be shorted or closed by some mistake, full battery voltage would be thrown on the motor, which would cause the motor to "run away" and destroy itself, as there would be no load to hold the speed down.




The batteries used in the Mark 18 torpedo have been so designed that they deliver maximum power and efficiency when they are at a temperature of 770-80° F. When the temperature falls, the efficiency falls 0.65 percent per degree Fahrenheit. Therefore, it can be seen that if the temperature falls to 40° F., the efficiency of the batteries will fall to 76 percent.

A heater has been installed in the battery cases of the Mark 18 torpedo (see section on batteries). This heater consists of thin strips of nichrome steel which heat up with the passage of a small current. These heater strips are placed between the batteries, and are all connected in series with jumper connections. This circuit is opened and closed by a relay which automatically keeps the temperature of the electrolyte between 82.4° and 89° F. The relay is secured to the wall of the motor compartment, just aft of the bulkhead. The two wires of the external heater circuit pass aft from the relay, along the bottom of the afterbody (to which they are secured by tape passed through holes in the strengthening rings). The circuits pass through the shell of the afterbody forward of the bottom vertical tail vane, through a micarta terminal block, which is secured to the heater flange. From this terminal block the wires pass through two copper tubes which are attached to a terminal cap. One tube passes on each side of the bottom vertical vane, through a slot behind the vane, and into the bottom shoe. The wires terminate in another micarta terminal block. Power for this circuit is put in from the outside by a cable connected to the terminal block in the bottom vane shoe. The cable is so held in the gland of the shoe, by a gland nut, that it breaks off outside the torpedo when it is fired.

Two thermostats are in series in the relay circuit. One is mounted on a battery connecting bar and responds to temperature of the electrolyte and plates. The other is imbedded under the wood in the "dummy cell" and responds to the wall temperature of the battery cell. This temperature must never exceed 140°-150° F., or the wall will start to soften. In operation, the heater warms up the outside wall of the battery and the wall slowly transfers this heat to the electrolyte. However, this transfer is slow, and the wall may heat up to a dangerous temperature in a short time. Therefore, the wall thermostat will automatically cut off the current until the wall has imparted its heat to the electrolyte, and has cooled down. This thermostat opens and closes more often than the one on the connector bar. Both thermostats, however, must be closed (as they are in series) for current to flow in the circuit and to energize the relay, closing the heating circuit and supplying power from the outside to heat the batteries.

The thermostats are designed to turn the heater on when the temperature of the thermostat falls below 82.4° F. (28° C.); and turn it off at approximately 89° F. (32°C.). If the thermostats become defective, they are to be replaced, as repair on these delicate devices in the field is impractical.

Power Required.

The heater circuit is designed to operate on approximately 230 volts A. C. or D. C. As the heaters have a resistance of 100 to 110 ohms, they will draw a current of approximately 2.3 amperes, or approximately 529 watts. If the voltage of the ship's power circuit varies over a large range, the operator must make certain that overvoltage is not applied to the heaters for any length of time. Undervoltage can be used; but this will take a much longer time to heat the batteries.

When torpedoes are in a "ready condition" or "fully-ready condition," for use on short notice, the batteries must be kept at the proper temperature, as heating them up to 82.4° F. might take Some time. The circuit has been so designed that the torpedo batteries may be kept at the proper temperatures while the torpedo is in the tube. Other torpedoes that are held


ready for use at any time should be similarly heated. Tests have shown that if the torpedo is immersed in water at 32° F., the battery electrolyte will cool from working temperature at a rate of 6 1/2 degrees per hour.

If the heater circuit fails to operate correctly with 230 volts applied:

1. Close relay by hand. If contacts do not arc when opened, check through the circuit to locate the "open."

2. If relay does not close and battery is cold, check voltage at coil-should be 12 volts. If voltage is low, the cells which supply power to the relay coil need charging.

3. If voltmeter reads "zero" at coil, jumper out thermostats one at a time. If thermostats are closed, locate the open in the relay coil circuit.

4. If there are 12 volts at the coil and current flowing, partly close relay by hand; and if it will now close, adjust the relay tension spring.

5. If relay still does not close, put in new coil.

6. If calibration of the thermostats seems wrong, they may be checked by putting thermometers in the electrolyte; one on the battery connection as near as possible to that thermostat and one as near as possible to the other thermostat against the battery cell wall. Bring up temperature of battery slowly; and in any case do not go above a temperature of 89° F. as measured on any one of the three thermostats.

NOTE.-The relay is mounted with the contact rocker arm down so that its weight tends to keep it open. If it is mounted in such a way that its weight tends to close it, the relay will not perform correctly.

Loss of Power Through Control Circuit.

There will be a constant drain on the cells connected in the control circuit, when the relay coil is energized. The resistance of the relay at 77° F. is approximately 26.35 ohms. After PA hours of operation, this will increase to 32.3 ohms. The voltage on this circuit is that of six cells in series, and will be 12.66, if the voltage per cell is calculated to be 2.11 on a closed circuit of this type. Thus, the current flowing through the relay circuit (if the leads are considered of negligible resistance) will be of the order of 0.3 ampere. Though this is a small current, if it is allowed to constantly drain the six cells in the circuit, these cells will fall in voltage faster than the remaining cells.

Treatment of these cells depends on the length of time that the heater and control circuits are used, and the length of time between battery charges. It is suggested that a close watch be kept on these six cells, and that they be used as pilot cells. It is possible that the leads could be changed to another group of six cells, if any drop in voltage is observed in the original six. On charge, and especially when an equalizing charge is being given, it would be well to continue charging the batteries until readings on the six control circuit cells come up to standard for full charge, and remain constant.

Disconnecting Heater Circuit Before Firing.

It is most important that the heater circuit be disconnected before actual firing. The circuit should contain a switch outside of the torpedo tube, so that the source of power in the vessel can be disconnected from the torpedo. Failure to do this before firing may result in a short circuit when the cable breaks.

If the torpedo is not going to be used for some time, and the batteries are in the battery compartment in a charged condition, it is suggested that the control circuit be broken at the relay, thus relieving the six cells from this constant drain. However, be sure to reconnect the circuit before making preliminary adjustments, and soon enough before firing to bring temperature up to 82.4° F.




Spare parts for the Mark 18 torpedo will be supplied as listed in stock and group sheets for this torpedo. Each spare part will be marked with the stock group or stock part number. This is for identification of all spare parts which will aid in replenishing stock. Stock groups will be assemblies. Stock parts will be individual parts.


Tools supplied for use on the Mark 18 torpedo in addition to standard torpedo tools are as follows:

Tool number: Use
158-W Forward propeller nut.
154-W After propeller nut.
157-W Propeller puller.
273-W Gear puller for removing forward bevel gear from propeller shaft.
268-W Propeller lock.
110-W 90°, 1/2" open end tool. Vertical rudder rod turnbuckle and lock nuts.
111-W 45°, 1/2" open end tool for vertical rudder rod turnbuckle and lock nuts.
116-W Straight Y2" open end tool for vertical rudder rod turnbuckle and lock nuts.
277-W Straight tool for turning depth rudder rod turnbuckle.
276-W 45°,0.692" open end tool for depth rudder rod turnbuckle lock nuts.
120-W For counter sunk head screws in idler gears.
112-W Battery compartment hand hole plates securing screws.
125-W Spanner nut on propeller shaft.
127-W Adjusting relief valve.
126-W Rudder rod packing glands.
280-W Starting gear lock (safety device).
286-W Side plug on starting gear.
115-W- Stop valve stem.
172-W Charging valve plug.
269-W Stop valve plug.
130-W Stop valve carrier.
230-W Leveling syringe for battery.
233-W Hydrometer. Specific gravity readings.
322-W Eye bolt for lifting motor.

The letter W signifies that the tool was developed and supplied by the Westinghouse Electric & Manufacturing Co. These tools will be used only as designated. Many of the standard torpedo tools are applicable to the Mark 18 and are to be used along with the sets supplied by manufacturer. The control mechanism and gyro tools are the same as those used on the Mark 14-3 torpedo.




Ordnance Pamphlet No. 946 has been given the following initial distribution:

Activity Number
of copies
Commander in Chief, U. S. Fleet 2
Commander in Chief, U. S. Pacific Fleet 2
Commander in Chief, U. S. Atlantic Fleet 2
Commander, Southwest Pacific Force 2
Commander, Southeast Pacific Force 2
Commander, South Pacific Force 2
Commander, U. S. Naval Forces in Europe 2
Commander, Service Force, Pacific Fleet 2
Commander, Service Force, Atlantic Fleet 2
Commander, Service Force, Southwest Pacific Fleet 2
Commander, Service Force, Pacific Fleet, Subordinate Command 2
Commander, Service Force, Atlantic Fleet, Subordinate Command 2
Commander, Service Force, Southwest Pacific Fleet Subordinate Command 2
Commander, South Atlantic Force 2
Commander, Submarine, Pacific Fleet 4
Commander, Submarine, Southwest Pacific Fleet 4
Commander, Submarine, Atlantic Fleet 4
Commander, Western Australian Force 2
Commander, U. S. Naval Bases, South Pacific Area 2
Commander, Submarine Squadrons 2
Commander, Submarine Divisions 2
Naval War College 2
Naval Academy 2
Submarine Bases 1 2
Destroyers Pacific Torpedo Shop 2
Naval Torpedo Stations 2
Fleet Schools (Torpedo only) 7
Naval Training Schools of Indoctrination (Fort Schuyler only) 2
General Ordnance School 2
Officer's Torpedo Schools 12
Torpedomen's Schools 7
Torpedo School 7
Post Graduate School 2
Submarine School 2
Fleet Service School (Torpedo only) 7
Motor Torpedo Boat Squadron, Training Center (Melville only) 2
Torpedo Testing Range 2
Submarines 2 2
Submarine Tenders 2
U. S. Naval Attaches (Alusna, London only) 2
Navy Yards (Mare Island, Philadelphia, Portsmouth) 2
Naval Operating Bases (Londonderry, Key West, and Viequies Sound only) 2
Naval Air Stations 3 2
Naval Proving Ground 2
Naval Gun Factory 2
Naval Ammunitions Depot (Burns City, Hawthorne only) 2
Naval Mine Depot (Yorktown only) 2
Secretary of the Navy 1

1 Midway, New London, Pearl Harbor, San Diego, St. Thomas, Coco Solo, Dutch Harbor, Kodiak, Sitka, Bermuda (Ordnance Island) only.

2 Applicable Submarines only.

3 Alameda, Argentina, Bermuda, Charlestown, Dutch Harbor, Unalaska, Guantanamo, Kodiak, Midway, Sitka, San Juan, Trinidad only.


Activity Number of copies
Vice Chief of Naval Operations 2
U. S. Marine Corps Headquarters 2
U. S. Coast Guard Headquarters 2
Chief of Ordnance, War Department 2
Applicable Secret Bases 2

Notification of any desired changes in the above distribution should be forwarded direct to the Bureau of Ordnance. Requests for additional copies of this Ordnance Pamphlet should be addressed to the Commandant and Superintendent, U. S. Naval Gun Factory, Navy Yard, Washington, D. C.; Commandant, Navy Yard, Mare Island, Calif.; or Officer in Charge, Ordnance Publications Subcenter, Naval Supply Depot, Pearl Harbor, T. H., U. S. A.



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