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
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
c. Individual guide pins. Individual guide
pins provide pump alignment for sections of
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
h. Races. Races become worn through
considerable operation and should be
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
Most submarine units have relief valves
mounted externally in the pressure line, in
which case the pump has a replenishing valve
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
Hele-Shaw, symbol 2250, viscosity 245
280 seconds Saybolt Universal at 130 degrees
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
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
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.
B. DETAILED SERVICE TROUBLES, CAUSES, AND REMEDIES
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.
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.
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.