Explains the different components of hydraulic system. Different types of hydraulic fluids used,safety devices used as well as pressure regulators used in the aircrafts. Different types of pumps used to drive the hydraulic fluid. Each sub system is explained with pictures from boeing 737 aircraft.

1. AIRCRAFT HYDRAULIC SYSTEM

3. What is Hydraulics?
• Hydraulics is derived from the Greek
word
- Hydor meaning Water
- Aulos meaning Pipe

4. Hydraulic System
• Hydraulic system has much advantage as
power sources for operating various a/c
used. It have many advantage –
•
• 1. Light weight
• 2. Easy installation
• 3. Simplification of inspection
• 4. Minimum maintenance requirement
• 5. Ease of detecting leaks

5. Hydraulic Fluid
• PROPERTIES OF HYDRAULIC FLUIDS-
• 1. Low viscosity
• 2. High chemical stability
• 3. High flash point
• 4 High fire point

6. Hydraulic Fluid
Types of oil
•1. Vegetable base (MIL-H-7644)
•2. Mineral base (MIL-H-5606)
•3. Phosphate ester base (SKYDROL)
•

7. Functions of Hydraulic OilFunctions of Hydraulic Oil
• It transmits power.It transmits power.
• It lubricates moving partsIt lubricates moving parts
• It seals clearances betweenIt seals clearances between
moving partsmoving parts
• It dissipates heat i.e. coolingIt dissipates heat i.e. cooling
purposespurposes

8. Simple Hydraulic system

9. Hydraulic System PartsHydraulic System Parts
• Reservoir/TankReservoir/Tank
• AccumulatorAccumulator
• FilterFilter
• Hydraulic PumpHydraulic Pump
• Directional Control ValveDirectional Control Valve

10. Reservoir Storing oil
It dissipates heat
It allows foreign particles to
settle down
Baffle separates inlet line
with the return line and
allows the air bubbles to
escape

11. Reservoir

12. FILTERSFILTERS
• There are basically threeThere are basically three
types of Filterstypes of Filters
- Suction line filters- Suction line filters
- Pressure line filters- Pressure line filters
- Return line filters- Return line filters

13. FILTERSFILTERS

14. PUMPSPUMPS
•Function of the Hydraulic Pump is to convert
Mechanical Energy to Hydraulic Energy
Engine driven pump

15. Tank
Pump
Electrically Driven PumpElectrically Driven Pump

16. AccumulatorAccumulator
• Absorbs the shocks due to rapid pressureAbsorbs the shocks due to rapid pressure
variations in a hydraulic systemvariations in a hydraulic system
• Helps maintain constant pressure withinHelps maintain constant pressure within
hydraulic systemhydraulic system
• Can be used as an emergency source ofCan be used as an emergency source of
powerpower

17. Tank
Pump
AccumulatorsAccumulators

18. Tank
Pump
AccumulatorsAccumulators

19. ROTARY & RECIPROCATINGROTARY & RECIPROCATING
TYPESTYPES
• Common Pumps in Rotary type are:Common Pumps in Rotary type are:
- Gear Pumps- Gear Pumps
- Vane Pumps- Vane Pumps
• Reciprocating type is given by:Reciprocating type is given by:

21. ACTUATORSACTUATORS
• An actuator is a mechanical device forAn actuator is a mechanical device for
moving or controlling a mechanism ormoving or controlling a mechanism or
system. An actuator typically is asystem. An actuator typically is a
mechanical device that takes energy &mechanical device that takes energy &
converts it to a desirable form for usage orconverts it to a desirable form for usage or
application.application.
Actuator
Pump
Tank

22. ACTUATORS Contd…ACTUATORS Contd…

24. Types of ValvesTypes of Valves
• There are three main types ofThere are three main types of
Valves:Valves:
- Pressure Control Valves (relief- Pressure Control Valves (relief
valves, pressure regulating valve,valves, pressure regulating valve,
pressure reducing valve)pressure reducing valve)
- Directional Control Valves (check- Directional Control Valves (check
valve)valve)
- Flow Control Valves (needle valve,- Flow Control Valves (needle valve,
throttle check valve etc.)throttle check valve etc.)

25. Relief valveRelief valve
• This is simply a pressure relief valve. If aThis is simply a pressure relief valve. If a
malfunction in the system causes themalfunction in the system causes the
pressure to rise too high, the relief valvepressure to rise too high, the relief valve
opens and the fluid simply passes back toopens and the fluid simply passes back to
the reservoir. In virtually all automotivethe reservoir. In virtually all automotive
power steering pumps, the relief valve ispower steering pumps, the relief valve is
built into the pumpbuilt into the pump

27. Some Hydraulic SymbolsSome Hydraulic Symbols