Hydraulics In Submarines

Hydraulics hydraulics [h drlliks ] noun study of fluids: the study of water or other fluids at rest or in motion, especially with respect to engineering applications

A Basic Hydraulic SystemIt necessarily includes the following basic equipment: 1. A reservoir, or supply tank, containing oil which is supplied to the system as needed and into which the oil from the return line flows. 2. A pump, which supplies the necessary working pressure.

3. A hydraulic cylinder, or actuating cylinder, which uses the hydraulic energy developed in the pump to move the door. 4. A cut-out valve, by means of which the pressure in the actuating cylinder may be maintained or released as desired. 5. A check valve, placed in the return line to permit fluid to move in only one direction. 6. Hydraulic lines, such as piping or hose, to connect the units to each other.

A SIMPLE HYDRAULIC SYSTEM

Hydraulic Power is now used above the other available sources of power on a submarine because of the drawbacks of the other sources. a) Hand Power: The use of Hand Power is rapidly decreasing because the power requirement is more than the manual power can supply for a long period of time. b) Electricity: One of the most important source of power on submarine. But it is not suitable for fine control because of the tendency of Overtravel or Drift. One more disadvantage is the noise.

NEED FOR HYDRAULIC POWER

c) Pneumatic Power: This system acts as a source of auxilary power but the maintainance and inefficieny are high. The compressed air storage and transfer is also hazardous on a submarine.

Advantages Of Hydraulic Systemi) Light in weight; ii) Simple and extremely reliable, requires minimum attention and maintenance. iii) Hydraulic controls are sensitive, and afford precise controllability. iv) Start and stop in complete obedience to the desires of the operator, and their operation is positive. v) Hydraulic systems are self-lubricated. vi) Their operation is not affected by salt spray or water. vii) Hydraulic units are relatively quiet in operation.

FACTOR Reliability Weight Installation Control Mechanism Maintenance Vulnerability

Response Controllability Quietness of Operation

ELECTRICITY Good Heavy Simple Switches and solenoids Constant attention Difficult, requiring necessary skilled personnel High pressure bottle Good dangerous; broken lines cause failure and danger to personnel and equipment Slow for both Rapid starting, slow starting and stopping stopping Poor Fair Poor Poor AIR Poor Light Simple Valves

HYDRAULICS Good Light Simple Valves Simple Safe; broken lines cause failure

Instant starting and stopping Good Good

Hydraulic System In SubmarinesIn a submarine, a single system actuates a multitude of devices and appears to be far more complete. In a submarine not one, but four Hydraulic Systems are employed: 1. The steering system, which operates the rudder. 2. The stern plane system, which tilts the stern diving planes to dive or rise. 3. The bow plane tilting system, which tilts the bow diving planes to rise or dive.

4. The main hydraulic system, which operates the following equipment. a. b. c. d. e. f. g. h. i. j. Flood and vent valves. Main air induction valve. Bow plane rigging. Windlass-and-capstan in bow. Main engine outboard exhaust valves. Torpedo tube outer doors. Emergency power for steering system if failure occurs. Emergency power for bow & stern plane tilting system. Periscope & Vertical Antenna hoists. Sound heads.

Main Hydraulic SystemThe units of the main hydraulic system fall conveniently into five groups: a. Power generating system. b. Floods and vents. c. Periscope and radio mast hoists. d. Forward and after service lines. e. Emergency systems.

Power Generating SystemThe power generating system consists of a group of units whose coordinated action provides the hydraulic power necessary for the operation of the main hydraulic system.

1) IMO pumps; 2) 18-horsepower motors; 3) automatic bypass and non-return valves; 4) accumulator; 5) pilot valve; 6) main supply tank; 7) main supply manifold; 8) main return manifold; 9) accumulator air flask; 10) back-pressure air, or volume, tank; 11) non-return valves; 12) air-loaded relief valve.

Components of Power Generating Systema. The IMO pumps (1) supply hydraulic power to the system. b. The main supply tank (6) contains the oil needed to keep the system filled. c. The accumulator (4), accumulates the oil from the pump and creates pressure oil which is maintained at a static head for instant use anywhere in the system. d. The main supply and return manifolds (7 and 8) act as distribution and receiving points for the oil used throughout the system.

e) The pilot valve (5) is a two-port, lap-fitted trunk, camoperated slide valve, directs the flow of oil that causes the automatic bypass valve to open or close. f) The automatic bypass and non return valves (3). The automatic bypass valve directs the flow of pressure oil in response to the action of the pilot valve. The non return valve prevents the oil from escaping through the open automatic bypass. g) Cut-out valves, serving various purposes throughout the system and nonreturn valves to permit one-way flow. h) The back-pressure tank, or volume tank (10), contains compressed air at a pressure of 10 to 25 pounds per square inch, which provides the air pressure on top of the oil in the main supply tank and maintains the entire system full of oil.

1. The accumulator air flask (9) serves as a volume tank for the accumulator, allowing the air to pass to and from it when the accumulator is loading or unloading.

Operation of Power Generating System not added

FLOOD AND VENT CONTROL SYSTEMThe ability of a submarine to attain neutral buoyancy, is effected by a series of tanks built around the pressure hull. These tanks are divided into separate compartments, which can be filled with sea water to submerge the vessel, and emptied by compressed air to restore positive buoyancy.

The tanks are classified and named according to their normal functions as follows: a. Main ballast tanks. comprise a principal group. They contain air when the vessel is surfaced, sea water when it is submerged. b. Fuel ballast tanks. carry fuel for the Diesel engines. Can also be used as MBT when empty. c. Negative and safety tanks. 1. The negative tank. used to get the vessel under rapidly, or if the vessel is already submerged, to make a quick descent to greater depth. called the negative tank because it provides negative buoyancy.

2. The safety tank. Its function is the opposite of that of the negative tank; that is, it provides positive buoyancy in an emergency situation. A special feature of both tanks is that they are constructed as strongly as the pressure hull itself, and hence can withstand full sea pressure at any working depth. d. The bow buoyancy tank. The bow buoyancy tank, is located in the bow of the vessel, and controls-its buoyancy. When the ship dives, this tank is flooded first to make the ship nose-heavy; when surfacing, it is blown out first, to make the ship rise by the bow.

PERISCOPE AND VERTICAL ANTENNA HOISTS On some later classes of submarines, the periscope and the vertical antenna are hydraulically operated, as units of the main hydraulic system. Each is raised and lowered by a hydraulic hoist. This consists essentially of a pair of long, vertically mounted hydraulic cylinders of small diameter, bracketed in the fairwater above the conning tower. Two piston rods emerge from the lower ends of the cylinders are yoked together and carry between them, in the yoke, the periscope or vertical antenna.

FORWARD AND AFTER SERVICE LINESThere are two sets of hydraulic lines extending from the main supply manifold and the main return manifold to both ends of the submarine. These lines, known as the forward and after service lines, furnish power to the following apparatus: a. The after service lines supply power for the operation of: 1. Main engine drowned-type exhaust valves. 2. Outer doors of the four after torpedo tubes.

b. The forward service lines supply power for the operation of: 1. Bow rigging. 2. Forward windlass-and-capstan. 3. Two echo-ranging and sound detection devices, known as the sound heads. 4. Outer doors of the six forward torpedo tubes.

Each equipment is operated by a hydraulic cylinder to which oil under pressure is directed by a control valve. The remainder of this section is devoted to a description of the hydraulic cylinders and control valves. Hydraulic pressure is distributed to the service lines at the main supply manifold by two valves. One line is marked SERVICE FORWARD, the other, SERVICE AFT. The return lines terminate in two similarly named valves of the main return manifold.

EMERGENCY STEERING AND PLANE TILTING SYSTEMSThey are both controlled by their individual Hydraulic Systems.

THE STEERING SYSTEMThe rudder of the submarine is moved by hydraulic power. Under normal conditions of operation the steering system has its own source of power, a motor-driven No. 5 Waterbury A-end pump, and is therefore, except in emergencies, completely independent of the main hydraulic system. The principal control units are assembled in the steering stand, located in the control room. However, there is an auxiliary steering wheel in the conning tower connected to the steering stand controls by a shaft, The submarine can be steered either from the control room or from the conning tower.

The steering system is so planned that three different methods of steering, based on three different sources of hydraulic power, are available. They are designated as follows: 1. POWER, in which the hydraulic power is independently developed by a motor driven pump belonging to the system itself. 2. HAND, in which the hydraulic power is developed in the telemotor pump by the direct manual efforts of the steersman. 3. EMERGENCY, in which the hydraulic power is supplied by the main hydraulic system. Note: The rudder itself is moved by hydraulic power in all three cases; the only difference between these methods is in the manner in which the power is developed.

The system may be conveniently thought of as divided into four principal parts: a. The normal power supply system, which consists of a Waterbury No. 5 A-end pump, the motor which drives it, the control cylinder, and the main manifold. b. The steering stand, which consists of the main steering wheel, emergency hand wheel, telemotor pump, pump control lever, change valve, emergency control valve, conning tower connecting shaft, and a clutch. c. The main cylinder assemblies, which consist of the cylinders and plungers and the mechanical rudder-angle indicator. d. The rudder assembly, which consists of the connecting rods and guides, the crosshead, and the rudder itself.

BOW AND STERN PLANE SYSTEMSHydraulic power is used to tilt the bow and stern planes. Each system (bow and stern planes) has its own power supply system. The control units for diving and rising are assembled in a diving control stand in the control room. There is a set of controls for stern plane tilting, a set for bow plane tilting, a control valve for bow plane rigging.

Three methods of plane tilting available at the control panel are: 1) POWER, in which power is developed independently in each plane tilting system by the motor-driven Waterbury A-end pump belonging to that system. 2) HAND, in which power is developed in the telemotor pump, connected to each system, by the manual efforts of the diving stand operator. 3) EMERGENCY, in which power is obtained from the main hydraulic system.

STERN PLANE SYSTEMThe units of the stern plane system fall conveniently into three groups: a. The control units at the diving control panel, consisting of handwheel, telemotor pump, change valve, and emergency control valve. b. The power supply system, consisting of a Waterbury A-end pump, the motor which drives it, the control cylinder, and two pressure relief valves. c. The main cylinder and planes assembly, consisting of the hydraulic cylinder, the piston, the piston rod, the guide cylinder and guide piston, and the tiller which tilts the planes.

Flow diagram of stern plane system. 1) Telemotor; 2) change valve; 3) control cylinder; 4) motor-driven Waterbury A-end pump; 5) ram assembly; 6) emergency control valve; 7) quadrant gear; 8) emergency control handwheel; 9) pump-stroke control lever; 10) centering spring; 11) relief valve manifold.

BOW PLANE SYSTEM

SERVICE TROUBLES, CAUSES, AND REMEDIESMain hydraulic systemPROBABLE CAUSES 1. Supply tank low on oil; pump has lost suction. 2.Supply cut-out valve closed. 3. Strainer clogged. 4. Foreign matter in pump. TROUBLE IMO pump very noisy. REMEDIES 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 1. Cut-out valve between 1. Open stop valve. bypass is closed. accumulator and accumulator air 2. This trouble will be indicated flask closed. as soon as the pump has been 2. Excessive oil added to oil seal, started and the hand bypass causing oil to spill over into closed. The oil pressure will go cylinder. higher and higher as the accumulator is loading. Drain oil 3. Accumulator air flask has from bottom of accumulator air accumulated excessive water. cylinder and also drain some oil from oil seal. 3. Drain accumulator air flask.