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AIRCRAFTS HYDRAULIC SYSTEM JANHARLAL.E.M. S-7 ME. NO.65.

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Presentation on theme: "AIRCRAFTS HYDRAULIC SYSTEM JANHARLAL.E.M. S-7 ME. NO.65."— Presentation transcript:

1 AIRCRAFTS HYDRAULIC SYSTEM JANHARLAL.E.M. S-7 ME. NO.65

2 B737 Hydraulic System

3 INTRODUCTION Hydraulics is based on the fact that liquids are incompressible Hydraulics is based on the fact that liquids are incompressible Hydraulic system is a system where liquid under pressure is used to transmit energy Hydraulic system is a system where liquid under pressure is used to transmit energy In it a hydraulic pump converts mechanical power to hydraulic power In it a hydraulic pump converts mechanical power to hydraulic power An actuating cylinder converts hydraulic power to mechanical power. An actuating cylinder converts hydraulic power to mechanical power.

4 A SIMPLE HYDRAULIC SYSTEM

5 DEVICES USING HYDRAULIC SYSTEMS IN AIRCRAFTS  Gun turrets  Auto pilot  Shock absorption systems  Dive, landing, speed and flap brakes  Bomb bay doors  Doors and hatchways  Landing gears, wing flaps, etc…

6 PRINCIPLES OF OPERATION Governed by Pascal’s law Governed by Pascal’s law The oil is in contact with both sides of the piston head but at different pressures. High pressure oil may be pumped into either side of the piston head. The oil is in contact with both sides of the piston head but at different pressures. High pressure oil may be pumped into either side of the piston head. The selector valve determines to which side of the actuating cylinder the high pressure oil (red colored side) is sent. The selector valve determines to which side of the actuating cylinder the high pressure oil (red colored side) is sent.

7 PARTS OF THE POWER SYSTEM RESERVOIR RESERVOIR ACCUMULATOR ACCUMULATOR FILTER FILTER POWER PUMP POWER PUMP SYSTEM RELIEF VALVE SYSTEM RELIEF VALVE PRESSURE REGULATOR PRESSURE REGULATOR

8 POWER SYSTEM

9 RESERVOIR FUNCTIONS Holds reserve supply oil to account for normal leakage, emergency supply of oil, volume changes, thermal contraction of oil, Holds reserve supply oil to account for normal leakage, emergency supply of oil, volume changes, thermal contraction of oil, Provides pressure head on the pump, a place to remove air or foam from liquid, air space for expansion of the oil due to temperature changes Provides pressure head on the pump, a place to remove air or foam from liquid, air space for expansion of the oil due to temperature changes etc etc

10 RESERVOIR CONSTRUCTION Material: 5052 aluminium Material: 5052 aluminium Size: takes into account all oil volumes in operational requirements, thermal expansion, leakage, etc. Size: takes into account all oil volumes in operational requirements, thermal expansion, leakage, etc. Shape: domed cylindrical shape, due to ease of construction & mounting Shape: domed cylindrical shape, due to ease of construction & mounting

11 ACCUMULATORS PRINCIPLE Gas valve lets in compressed gas at ½ system pressure Gas valve lets in compressed gas at ½ system pressure Diaphragm pops up & oil is sent through system Diaphragm pops up & oil is sent through system When system pressure>accumulator pressure, diaphragm deploys When system pressure>accumulator pressure, diaphragm deploys

12 ACCUMULATORS USES Absorbs the shocks due to rapid pressure variations in a hydraulic system Absorbs the shocks due to rapid pressure variations in a hydraulic system Helps maintain a constant pressure within the hydraulic system Helps maintain a constant pressure within the hydraulic system Helps the hydraulic pump under peak pressure loads Helps the hydraulic pump under peak pressure loads It is an emergency source of power It is an emergency source of power Spherical shape is preferred for accumulators Spherical shape is preferred for accumulators

13 POWER PUMPS FUNCTION Is to change mechanical horsepower to hydraulic horsepower Is to change mechanical horsepower to hydraulic horsepowerTYPES Gear pumps: move fluid based upon the number of gear teeth and the volume spacing between gear teeth. Gear pumps: move fluid based upon the number of gear teeth and the volume spacing between gear teeth. Piston pumps: move fluid by pushing it through the motion of the pistons within the pump Piston pumps: move fluid by pushing it through the motion of the pistons within the pump

14 POWER PUMPS PRINCIPLES OF GEAR PUMPS The liquid from the reservoir is pushed between the gear teeth. The liquid from the reservoir is pushed between the gear teeth. The oil is moved around to the other side by the action of the drive gear itself and sent through the pressure line. The oil is moved around to the other side by the action of the drive gear itself and sent through the pressure line.

15 POWER PUMPS PRINCIPLES OF RECIPROCATING PISTON PUMP As the cylinder block rotates, space between the block and the pistons increase, letting in more oil. As the cylinder block rotates, space between the block and the pistons increase, letting in more oil. As the block rotates from bottom dead center, the reverse occurs and the pistons push oil out through the outlet As the block rotates from bottom dead center, the reverse occurs and the pistons push oil out through the outlet

16 SYSTEM RELIEF VALVE PRINCIPLE The adjustment screw is set for a certain pressure value P2. The adjustment screw is set for a certain pressure value P2. When the pressure increases, the poppet will move up, forcing the excess liquid in When the pressure increases, the poppet will move up, forcing the excess liquid in

17 Douglass Pressure Regulator High pressure oil from the power pump opens valve C and also act on piston A High pressure oil from the power pump opens valve C and also act on piston A Piston A pushes Ball B off seat D, the oil goes through passage D into the center chamber back to the reservoir. Piston A pushes Ball B off seat D, the oil goes through passage D into the center chamber back to the reservoir.

18 HAND PUMPS Single Action Single Impulse Used for testing on ground and for Emergency

19 Selector Valves Position (1) is the position of the selector valve, for example, upon the extension of the landing gear or the lowering of flaps. Position (1) is the position of the selector valve, for example, upon the extension of the landing gear or the lowering of flaps. Position (2) is the position of the selector valve upon retraction of the landing gear or the raising of the flaps Position (2) is the position of the selector valve upon retraction of the landing gear or the raising of the flaps

20 ACTUATION CYLINDER The function is to take the pressure & hydraulic fluid flow & change them into linear or rotary motion. The function is to take the pressure & hydraulic fluid flow & change them into linear or rotary motion. Single piston double rod is an equal displacement cylinder used in aileron system or automatic guidance system Single piston double rod is an equal displacement cylinder used in aileron system or automatic guidance system Double piston-double rod actuating cylinder used in bomb bay doors Double piston-double rod actuating cylinder used in bomb bay doors

21 ADVANTAGES It is lighter in weight than alternate existing systems. It is lighter in weight than alternate existing systems. It is dead beat, that is, there is an absence of sloppiness in its response to demands placed on the system. It is dead beat, that is, there is an absence of sloppiness in its response to demands placed on the system. It is reliable; either it works or doesn't. It is reliable; either it works or doesn't. It can be easily maintained. It can be easily maintained. It is not a shock hazard; it is not much of a fire hazard. It is not a shock hazard; it is not much of a fire hazard. It can develop practically unlimited force or torque. It can develop practically unlimited force or torque.

22 CONCLUSION Hydraulic systems determine flight worthiness, usability and reliability. Hydraulic systems determine flight worthiness, usability and reliability.


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