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6A1. General.The submarine hydraulic system, like any other complex mechanism, will not function at maximum efficiency unless it is kept in perfect condition. This chapter lists some common service troubles, with their probable causes and suggested remedies.

6A2. IMO pump: troubles and repairs. a. Packing. The packing is a 8-inch-square flexible metallic packing (five rings). Adjustment is made with the pump in operation.

b. Adjusting bolts. Adjusting belts should be left at factory position. Any change will cause faulty alignment to the pump block bore.

c. Individual guide pins. Individual guide pins provide pump alignment for sections of block bore.

6A3. Waterbury pump: troubles and repairs. a. Oil seal. The most common trouble is with the seal. If it leaks excessively, it should be completely renewed. The shaft should be checked for burrs when removing the key from the keyway to make sure that seal ring burrs do not damage the ring when putting on new neoprene. Vaseline should be used to enable the ring to slip easily over the shaft and into place. The pressure surface of the steel seal ring should be checked to see that it has flat and sharp surfaces to insure a good seal. Also the end-plate of the pump should have a similar pressure surface.

b. Control shaft. No end-play of the control shaft is tolerated.

c. Piston socket and socket ring socket joints. The clearance allowed for No. 5 units is 1/2-thousandth of an inch. Any clearance greater than this will cause noisy operation.

d. Pistons. Pistons are not interchangeable.

e. Cylinder barrel and valve plate. The pressure surfaces of the cylinder barrel and

  valve plate must be sharp and flat to insure a good oil seal.

f. Cylinder barrel. The cylinder barrel must be set within 0.002-inch clearance on barrel keys to permit the barrel to be maintained against the valve plate when the shaft is forced back by thrust.

g. Roller bearing (axial thrust and radial thrust). Rollers occasionally crack and break. When facilities permit, renew the entire bearing. If bearings are not available, rollers can be staggered to equalize the load onto the bearing.

h. Races. Races become worn through considerable operation and should be renewed.

i. Relief-replenishing valves. Relief-replenishing valves should be checked periodically to see if the ball check is worn and to check the seats of the valve.

Check the spring to see if it is in proper tension.

Most submarine units have relief valves mounted externally in the pressure line, in which case the pump has a replenishing valve only.

6A4. Oils. Approved oils for use with hydraulic power transmissions are covered by yearly contracts and carried in stock as force feed and motor cylinder oil, light, and should be used as follows:

Waterbury, and Northern, symbol 2110, viscosity 90-120 seconds Saybolt Universal at 130 degrees Fahrenheit.

Northern, symbol 2075, viscosity 70-90 seconds Saybolt Universal at 130 degrees Fahrenheit.

Hele-Shaw, symbol 2250, viscosity 245 280 seconds Saybolt Universal at 130 degrees Fahrenheit.

When very low temperatures are expected, ice machine oil, also procured under


yearly contract, should be used temporarily. However, oils with a pour point as low as zero degrees Fahrenheit or lower have been tested in speed gears at temperatures causing complete solidification and found to work satisfactorily, as they liquefy almost immediately when the gear is operated. Manufacturers' instruction books should also be consulted for recommended grades of oil.

It is not necessary that all oil used in any installation be of the same brand or trade mark, provided it is all of the same grade.

The most efficient working temperature of a hydraulic unit is 120 degrees Fahrenheit, considering the question of wear. In close coupled installations, oil temperature may attain 200 degrees Fahrenheit. In other installations where there are large radiating surfaces, the temperature of the oil seldom exceeds 140 degrees Fahrenheit. When running under continuous load, cooling of the oil may be necessary if operating temperatures exceed 200 degrees Fahrenheit, in which case the Bureau of Ships should be advised.

6A5. Venting. a. Venting the main hydraulic system. When the main supply tank has been filled with oil, the operator should open the air bleeder valves one at a time throughout the power generating system until a solid stream of oil flows out of the bleeder valve.

To vent the lines and unit cylinders of air, place the control manifold levers on the HAND position and build up the air pressure in the volume tank to 25 pounds. Then open all bleeder valves throughout the ship, one at a time until no more air is present. Operate the units by hydraulic power a few times. Repeat the above procedure again. This will have to be done a few times until all the air is vented off. It should be noted that the unit cylinders in present installations are the highest points in the main system.

b. Venting the steering system. 1. Steering control system. In venting the steering control system the following units are vented: control cylinders, change valve, active side of telemotor pump, and the lines leading from the telemotor to the control cylinders.

Before venting the system, the following

  valves must be opened or closed. The two filling and vent control valves on the vent and replenishing manifold are opened, and the control line valve on the vent and replenishing manifold is closed. The bypass valve, between the two control lines by the control cylinder is open. The change valve should be on POWER.

The operator turns the steering wheel to the right. The telemotor pump takes a suction from the main supply tank through one of the opened filling and control valves and delivers the oil through the right rudder control line through the opened bypass valve by the control cylinders. From there it passes back through the left rudder control line, through the other opened filling and vent control valve, to the vent and replenishing line, and back to the supply tank.

The air is picked up by the oil being pumped through the lines and left in the supply tank. However, some of the air will still remain in the lines and must be vented off through the air bleeder valves located at all high points of the lines.

2. Main steering power system. In venting the steering power system the following units are vented: the four ram cylinders, the main steering manifold, the active side of the motor-driven pump, and the hand and emergency lines.

In filling and venting the steering power system, emergency power (for example, power from the main hydraulic system) is used. Shift to emergency steering in the control room (see Section 4C4), open the bypass, valve on the maim steering manifold, then turn the emergency steering wheel to left or right rudder. This will allow the oil from the main hydraulic system to pass through the hand and emergency return line to the main supply tank, carrying the air with it.

To create pressure in the ram cylinders, manifolds and lines, close the emergency steering return valve on the main return manifold, restricting the flow until the oil pressure shown on the steering gages reaches 200 pounds per square inch; the pressure will then be the same throughout the entire


steering power system. Begin venting the air out of the lines, cylinders, manifold, and pump through the air bleeder valves. This procedure must be repeated as often as is necessary to eliminate all the air from the system.

To eliminate air from the ram cylinders, the following procedure should be followed. When the boat is diving, the steersman should shift the rudder slowly from left to right a few degrees, with the steering in normal POWER or EMERGENCY; as he does so, vent the two after cylinders. As the angle of the boat is down by the bow, the after cylinders will be at an up angle and all the air in them will be trapped at the air bleeder valve, allowing it to be vented off. The same procedure should be followed for the forward cylinders when the boat is surfacing.

WARNING. Never open the air bleeder valve unless the oil pressure is being directed to that cylinder, as air would be drawn in the pump as it is taking a suction on that cylinder. Always open the air bleeder valve to the cylinder that has pressure directed to it.

  c. Venting the bow and stern plane control system. These systems are vented in the same way as the steering control system, except that the diving wheels must be turned toward DIVE.

d. Venting the bow and stern plane power system. In venting the bow and stern plane power system, shift to EMERGENCY power.

Rig out the bow planes, tilt them to hard dive (against the stops), and with emergency power on the dive pressure line, vent that line through the air bleeder valves; this includes the bottom part of the tilting cylinder, rigging interlock, and tilting interlock. When all air has been vented from that part of the system, shift planes to hard rise and vent the rise pressure line through the air bleeder valves; this includes the top of the tilting cylinder, rigging interlock, and tilting interlock.

e. Venting the stern planes. With emergency power on stern planes, tilt the planes to hard dive, vent the dive pressure line through the air bleeder valves until all air has been vented. Shift planes to hard rise, and vent the rise pressure line until all air has been vented.

6B1. Main hydraulic system.
IMO pump very noisy. 1. Supply tank low on oil; pump has lost suction.

2.Supply cut-out valve closed.

3. Strainer clogged.

4. Foreign matter in pump.

1. Replenish oil to proper level in supply tank.

2. Open supply tank cut-out valve.

3. Clean strainer.

4. Disassemble pump, clean, and renew damaged parts.

Excessive oil pressure when hand bypass is closed. 1. Cut-out valve between accumulator and accumulator air flask closed.

2. Excessive oil added to oil seal, causing oil to spill over into cylinder.

3. Accumulator air flask has accumulated excessive water.

1. Open stop valve.

2. This trouble will be indicated as soon as the pump has been started and the hand bypass closed. The oil pressure will go higher and higher as the accumulator is loading. Drain oil from bottom of accumulator air cylinder and also drain some oil from oil seal.

3. Drain accumulator air flask.


Accumulator plunger squeaks or jumps when discharging. 1. Lost oil seal.

2. Packing gland uneven.

1. Renew oil seal.

2. Take up or loosen up on packing-gland nuts until gland seats evenly all around.

Accumulator plunger travels down against positive stops, causing oil relief valves to lift. 1. Valves in pilot valve or automatic bypass control lines closed.

2. Automatic bypass valve stem bent.

3. Foreign matter in automatic bypass piston.

4. Leather guide cup washer worn.

1. Open cut-out.

2. Manufacture and install new valve and piston unit.

3. Disassemble automatic bypass and clean.

4. Renew leather cup washer. If none is available, take a cut on the small brass washer on top of the cup washer.

Accumulator cycles continuously with all control valves under pressure. 1. Spool valves and their cylinders are worn, allowing oil to leak from pressure side to return side of system. 1. Rebore and relap cylinders. Manufacture and lap spool valves.
Accumulator cycles continuously when quick-throw valve on main supply manifold is closed. 1. Nonreturn valve leaking. 2. Automatic bypass valve piston leaking excessively.

3. Nonreturn valve sticking; pilot valve plunger worn.

1. Grind in and free up valve.

2. Rebore and relap automatic bypass valve. Manufacture new piston and valve.

3. Renew.

Accumulator short cycles. 1. Nonreturn valve leaking.

2. Automatic bypass valve piston leaking excessively.

3. Nonreturn valve sticking; pilot valve plunger worn.

1. Rebore and relap pilot valve cylinders and manufacture new piston.

2. Same as No. 1

3. Tighten holding-down bolts.

Loss of air from accumulator air flask. 1. Oil seal in accumulator lost.

2. Packing glands on valves leaking.

3. Bleeder valve leaking.

4. Relief valve leaking.

1. Renew oil seal. This is the most common trouble.

2. Tighten packing glands.

3. Grind in bleeder valve.

4. Grind in and reset relief valve.

Male and female joints leaking oil. 1. Improperly set up.

2. Copper gasket too hard.

1. Anneal copper gasket and set up evenly on all bolts of the flange.

2. Same as No. 1.


Valve on main supply or return manifold cannot be opened. 1. Valve jammed on seat. 1. Loosen valve body, loosen packing-gland nut, then open valve before tightening valve body.
Hydraulically operated unit cannot be started. 1. Foreign matter in operating mechanism.

2. Lack of lubrication.

1. Clean mechanism.

2. Thoroughly grease and lubricate operating mechanisms.

Leakage of oil at operating end of unit cylinder and piston. 1. Packing gland leaking.

2. Piston head plug leaking.

1. Loosen packing gland; operate unit allowing sufficient oil to flow out through packing; then tighten.

2. Remove cylinder head, remove piston head plug, and anneal copper gasket which is under the plug.

Note: The operator must look very closely to determine whether the oil is leaking from the packing gland or from the piston, as they are very close together.

Control manifold valve stuck with no pressure on system. 1. The valves and cylinders are so made that the valves are lapped into the cylinder, which makes it very hard to operate. As soon as the system is under pressure, they operate freely, as the cylinders are expanded by the pressure of the oil. 1. None.
Control manifold valve stuck with system under operating pressure. 1. Foreign matter between valve and cylinder.

2. Operating linkage frozen.

3. Improperly lapped.

1. Remove valve, flush cylinder, and clean valve.

2. Disassemble and free up.

3. Remove valve and polish with crocus cloth.

Main ballast tank vent or any hydraulically operated unit closes or opens when lever on control manifold is set in HAND or EMERGENCY position. 1. Valve unit improperly set, not allowing operating mechanism to go into locked position.

2. Unit mechanism dirty, lack of lubrication.

3. Spool valve in control manifold improperly set.

1. Chalk-mark valve seat, measure valve opening, and then set valve to proper clearances.

2. Lubricate unit thoroughly.

3. Spool valve may not overlap ports properly, allowing pressure oil to flow to open or closed side of valves.


Safety or negative flood valve does not indicate CLOSED, and operator is unable to close it by hand operation. 1. Ball joint(s) on flood valve out of adjustment.

2. Frozen operating mechanism.

1. Readjust ball joint. It will have to be partially unscrewed from the flood valve.

2. Grease and free mechanisms.

Safety or negative flood valve indicates CLOSED but tanks continue to flood. 1. Ball joint(s) on flood valve out of adjustment.

2. Gaskets blown out.

3. Sea connection lines leading through tank are leaking.

1. Readjust ball joint(s). It will have to be screwed part of the way into the valve.

2. Renew gasket.

3. Plug line and renew or put on temporary patch.

6B2. Steering system.
Rumbling noise in steering system when system is being operated. 1. Air in system. 1. Vent system.
Steering pump very noisy, with loss of power. 1. Pump casing not full of oil.

2. System air bound.

1. Vent, then fill surge tank with oil.

2. Vent system.

Rudder oscillates back and forth when steering wheel is not being moved. 1. Air in system.

2. Control mechanism binding.

3. Lack of lubrication on bearings of control mechanisms.

1. Vent system.

2. Free any tight joints on control mechanisms.

3. Grease all bearings.

Rudder continues to move in direction in which steering wheel was last turned. 1. Packing gland too tight on control cylinder.

2. Control linkage joints too tight.

3. Control linkage joints too loose; keys and keyways have excessive clearance.

1. Loosen packing gland.

2. Loosen and grease linkage bearings.

3. Disassemble and refit bearings and keys.

Rudder creeps in one direction, for example, if steering wheel is turned for right rudder, then as the rudder stops at a given degree of rudder, it starts back to left rudder without moving the steering wheel. 1. Steering pump tilt-box control shaft not set on neutral.

2. Centering spring has too much tension

3. Centering spring has too little tension

1. Loosen locking nut on trunnion on control shaft; rotate trunnion until tilt-box control shaft is in neutral position.

2. Readjust springs.

3. Readjust springs.


Rudder operates with jerky motion. 1. Packing on steering rams of rams dry. 1. Grease exposed sections of rams, allowing ram to carry lubricant into packing. Use a heavy oil (Symbol 5190).
Rudder operates at normal rate of speed in one direction, but operates at a reduced rate in opposite direction. 1. Control cylinder plunger stops incorrectly set.

2. Control cylinder packing is not allowing plunger to travel freely in opposite direction.

1. Reset control cylinder plunger stops.

2. Loosen packing until plunger operates freely.

In hand or emergency steering, the steering pump and motor turn when pressure is applied to rams. 1. Motor brake does not hold. 1. Readjust brake.

Note: Check neutral setting of tilting block on pump.

Sufficient pressure cannot be built up with hand steering to move rudder. 1. Excessive leakage between ports of change valve.

2. Bypass or relief valves on main steering manifold leaking.

3. Control room steering pump leaking excessively by piston or between cylinder barrel and valve plate.

1. Renew change valve.

2. Grind in relief and bypass valves.

3. Completely overhaul steering pump.

Squealing noise is heard in the A. T. tank when rudder is operated. 1. Connecting rod guide and cylinder binding. 1. Grease.

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