Airframes & Systems

a) to store limited amount of energy (pressure)

b) to damp pressure ripples in the hydraulic system => maintain pressure at a pre-set level 

c) acts as a flexible wall => allows teh fluid to change its volume according to the fluid temperature variation 

to transform pressure and fluid dlow into mechanical force or motion to perform work

=> consists of a cylinder, pistons and piston roads

=> some are double acting  

=> brake one direction only 

For safety reasons: by two actuator or tandem acuators

=>hydraulic pressure is lost from one or more systems => control surface still remains movable => switched into the damping mode = allows a free circulation of the hydraulic fluid from one side of the actuator to the oter

=> usually powered by two pumps which one EDP and the other ACP

1. EDP: engine driven pumps

2. ACP= alternate current pump or EMDP= elecric motor driven pump

3. ADP= air driven pump => A turbine driven by air from the pneumatic system, powers the hydraulic pump

4. PTU= Power transfer unit hydraulic driven pump => allows the system pressure to be built up by the first system without connecting the fluid lines

5. RAT: emergency => Ram air driven pump

Engine driven pump 

Alternate current pump or Electric motor driven pump

air driven pump

Power transfer units

is an automatic control and drive mechanism to ensure reaching a defined set value from any actual position of an operational unit

constant delivery

1.) pilot teh direction of flow

2.) rate of flow

3.) pressure at different operating units 

high Flash Point.

when the fluid delivery pressure is less then the fluid outlet pressure.

An alternate pump, driven by an air flow when extended, used to pressurize a hydraulic system in case all hydraulic power is lost.

A pump diven by a hydraulic system to pressurise a failed hydraulic system.

at a right angle with the driving shaft.

to minimise pump wear by providing a fluid idling circuit when the system is at full charge pressure.

the force produced will be greater from the piston face opposite to the rod.

carry the aeroplane during ground operation and to absorb (auffangen) the impact upon landing

Dry air or nitrogen is the spring element and the hydraulic fluid serves as a damping element

teh outer and inner cylinders are of axial symmetric shape => connected by a torsion link => secures the tracking (Spur) of the wheels => marked by overload marks (reduced ir inoperative damping )

The wheel consists of rim and type (Reifen) => Rims are divided in two halves for easy tyre fitting => brakes are mechanically connected to the rims

made of aluminium alloys to save weight

Reifen => usually preferable

The strength of the tyre depends on the number of plies (play rating)

the wire bead helps to keep the tyre on the rim and the side wall keeps the tie tight

inflated => uneven abrasion/ decreased breaking ability/ decreasing steering ability

a rotor (disk) and a stator => the rotor is connected to the wheel and brake housing (Stator) => Brakes are part of the passive hydraulic system

to actuate the brakes and then pull or switch the parking brake lever => not suitable for safely parking the aircraft for longer periods

1. nose gear => mechanical link between teh rudder pedals and the nose gear => small deflection on each side 8-10 Grad

2. steering => to apply either the left or right main wheel brake => Acts like a castor => the nose wheel swivels (drehen) only within a small range 

drehen

always installed in order to suppress the possible fluttering of the nose wheel during ground operation =>nose and am wheel => by hydraulic damping

hydraulic or electric => Screw spindles move the radius struts which extended or retract the gears

Some gears are equipped with separate lock struts which lock the side struts by over centering