Hydraulics Midterm

Question 0

Explain Pascal’s Law in your own words.

Answer 0

When pressure is exerted on a volume of liquid in a container, the pressure will be transferred equally throughout the container and undiminished at 90° to the walls.

Question 1

What are the two types of hydraulic systems? Which one is not used in aviation?

Answer 1

Open and closed, open is not used in aviation.

Question 2

The pressure exerted on the base of a column of liquid, due to the weight of that liquid, is dependent upon what one thing?

Answer 2

The height of the column.

Question 3

What is the major difference between hydraulics and pneumatics?

Answer 3

Hydraulics uses liquids (non-compressible) whereas pneumatics uses air (compressible)

Question 4

What are the three basic things/components of any hydraulic system?

Answer 4

Means to produce fluid flow
Means to transmit the flow
Means to use the power

Question 5

What are the two types of hydraulic actuators?

Answer 5

Single acting and double acting.

Question 6

What is the difference between a closed center system and an open center system?

Answer 6

The center is closed in a closed center system, in an open

center system the center is open, when the selector valve is in the neutral position.

Question 7

In which system is some type of unloading valve necessary, an open or closed system?

Answer 7

Closed system.

Question 8

What is the relationship between volume, area and distance?

Answer 8

V=AxD

Question 9

What are the two purposes of hydraulic fluid?

Answer 9

To transfer force to another place where work is done

Lubrication

Question 10

What are the four desirable characteristics/properties of hydraulic fluid, as discussed in class?

Answer 10

High viscosity
Low flash point
Low fire point
Chemical stability

Question 11

List the three types of hydraulics fluids currently in use.

Answer 11

Vegetable, mineral, skydrol

Question 12

What is the mil spec number for vegetable base fluid?

Answer 12

7644

Question 13

What is the mil spec number for mineral base fluid?

Answer 13

5606

Question 14

What is the mil spec number for skydrol?

Answer 14

8446

Question 15

What color is vegetable?

Answer 15

Blue

Question 16

What color is mineral?

Answer 16

Red

Question 17

What colour is skydrol?

Answer 17

Purple

Question 18

What do you flush vegetable base with?

Answer 18

Isopropyl alcohol

Question 19

What is mineral fluid flushed with?

Answer 19

Naphtha and stoddard

Question 20

What is skydrol flushed with?

Answer 20

mEK

Question 21

What are the three purposes of a reservoir?

Answer 21

To contain hydraulic fluid
To allow for expansion purge air
To direct hydraulic fluid

Question 22

List the three types of filters

Answer 22

Ceramic paper wire mesh

Question 23

What are the two purposes of a hand pump?

Answer 23

Ground ops

Emergencies

Question 24

What is the purpose of a main power pump in a hydraulic system?

Answer 24

The pump the fluid through the system during normal operations.

Question 25

What are two means of driving a power pump?

Answer 25

Engine driven

Electrically driven

Question 26

What are the four types of pumps discussed in lecture?

Answer 26

Gerotor
Gear type
Vane
Piston

Question 27

How the engine protected in case of a seized pump?

Answer 27

Through the use of a shear shaft.

Question 28

What must be incorporated in a system, or the pump itself, when a constant displacement is used, that need not be user when a variable displacement pump is used?

Answer 28

A relief valve.

Question 29

Name two types of hand pumps.

Answer 29

Single acting

Double acting