ACA0205 hydraulic systems

Pascals law

pressure applied to a confined liquid is transmitted equally in all directions without the loss of pressure and acts with equal force on equal surfaces

pressure

force per unit area

what is exchanged for the change in force in a hydraulic system

linear displacement / distance traveled

main purpose of a hydraulic system is to

multiply force

aircraft hydraulic systems consists two power systems

power control system

utility control system

the power control system does what

supplies fluid pressure to flight controls only

the utility control system does what

supplies fluid pressure to the utility system in addition to other flight controls

what do manufacturers refer to when talking about the power control systems

systems supplying pressure only for the flight controls

reservoir does what?

1. storage

2. heat dissipation

3. air removal

4. FOD removal

5. thermal expansion

non-pressurized reservoirs definition

vented to the ambient air to prevent a vacuum from being formed as the fluid level decreases

pressurized reservoirs definition

pressurized by bleed air from the compressor or by hydraulic system pressure

hand pump

is a back up hydraulic system

provides alternate hydraulic power

emergency system

power pumps

normally driven by the engine but may be electric motor driven. displace a variable or constant amount of fluid

variable displacement pump

regulates volume delivery in accordance with system flow demands

constant displacement pump

delivers a constant fluid output for any given rotational speed

pressure regulator or unloader valve

works in conjunction with the constant displacement pump; maintains system set pressure, displaces excess fluid from pump back to reservoir

check valve

allows one way flow in a hydraulic system

accumulator

Shock absorption

provide pressure for 1x emergency

assist pressure in peak operations

maintain pressure during shutdown (check valves)

Filters

ensure delivery of contaminant free hydraulic fluid by preventing dust, grit, and undesirable impurities from entering the system

relief valves

pressure limiting device, prevents pressure buildup

allows fluid to flow back to reservoir

prevents seals from bursting/container damage

pressure gauges

indicates hydraulic system pressure

pressure switches

used to indicate a hydraulic pressure drop that falls below allowable limits

hydraulic fuses

safety devices throughout a hydraulic system to detect ruptures, failed fittings, or other leak producing failures

selector control valves

direct the flow of hydraulic fluid

can be positioned manually or electrically

actuators

convert fluid under pressure into linear or reciprocating mechanical motion