Hydraulics and pneumatics

Question 1

The three types of hydraulic fluid -

Answer 1

Vegetable based fluid

Mineral based fluid

synthetic fluid

Question 2

a phosphate ester based fluid, is?

Answer 2

a synthetic fluid

Question 3

a kerosene-type fluid is -

Answer 3

a mineral based fluid

Question 4

a castor oil and alcohol fluid is -

Answer 4

vegetable based fluid

Question 5

the type of fluid that offers best resistance to fire - is?

Answer 5

synthetic based fluid

Question 6

Accumulators are used to -

Answer 6

to store hydraulic fluid under pressure.

Question 7

For light aeroplanes the type of hydraulic pump that is satisfactory?

Answer 7

Electrically driven pump

Question 8

For larger aircraft, for which electrically driven pumps are not satisfactory, what type of hydraulic pump is used?

Answer 8

an engine driven pump

Question 9

What type of engine driven pump:

This type of pump delivers a constant amount of fluid each time it rotates, irrespective of system demand.

Answer 9

A constant delivery pump or fixed volume pump

Question 10

What type of engine driven pump:

This type of pump delivers a volume of fluid which is proportional to the demands of the particular system.

Answer 10

Constant pressure or variable volume pump

Question 11

In the case of jet aircraft engine failure, hydraulic pressure is provided through an -

Answer 11

air pump driven by compressor bleed air

Question 12

What type of valve:

These are used in constant delivery pump systems and will open to divert fluid back to the reservoir once the required line pressure has been reached.

And what are they also referred as?

Answer 12

This is an automatic cut-out valve

Also referred to has pressure regulators

Question 13

Automatic cut-out valves, are referred to as pressure regulators, fulfil what three tasks?

Answer 13

1. to ensure the output pressure of a pump is maintained within a predetermined range.
2. to permit the pump to turn without resistance once normal system pressure is attained
3. to unload pump when abnormally high pressures exist

Question 14

What type of valve:

The purpose of this valve is to maintain the required, or pre-set, pressure to a primary, or essential, hydraulic service regardless of the demands of a secondary service. Only once pressure exceeds the set value will the valve open to allow pressure to a secondary system.

Answer 14

Pressure maintaining or priority valve

Question 15

What type of valve:

The valve accept normal pressure form the hydraulic system and reduce it to provide pressure to low pressure systems such as brakes

Answer 15

pressure reducing valve

Question 16

What type of valve:

This allows full flow in one direction and a limited flow in the opposite direction, providing a means to control the speed of operation of a particular system such as flap retraction.

Answer 16

Restrictor valve

Question 17

What type of valve:

The ideal example of the operation of this type of valve is a retractable undercarriage system, operation of the valve prevents the wheels from being extended or retracted before the doors are open

Answer 17

Sequence valve

Question 18

What type of valve:

This type of valve is used on anti-skid systems where they initially allow a full flow of fluid and than gradually reduce to a restricted flow. this allows the anti-skid system to release the brakes

Answer 18

Modulators

Question 19

What type of valve:

these can be operated both manually or electrically and are used to activate various systems, such as the flaps or undercarriage, by directing fluid to a particular unit.

Answer 19

Selector valves

Question 20

What type of valve:

This valve is a device, usually incorporated in vital hydraulic systems such as flaps, undercarriage or brakes, which allow the use of an alternate hydraulic pressure supply in the event of the failure of the normal supply.

Answer 20

Shuttle valves