Hydraulics Part 1

Question 1

A reservoir is provided in the hydraulic system as a storage space for the fluid, but also to act as -

It also serves as a place in -

Answer 1

an expansion chamber to allow for variations in the volume of fluid caused by thermal expansion

which any air can be removed from the fluid

Question 2

Non-pressurised reservoir:

In this system, the flow of fluid is due to -

Answer 2

atmospheric pressure and gravity.

Question 3

Pressurised reservoirs are used in aircraft -

Answer 3

that fly at high altitudes to reduce foaming and to provide pressure since atmospheric pressures are low.

Question 4

Pressure is supplied to a pressurised reservoir by -

Answer 4

either the compressor of a turbine engine or from the aeroplane’s cabin pressurisation system.

Question 5

Accumulators are incorporated in constant delivery systems to store hydraulic fluid -

Answer 5

under pressure

Question 6

Accumulators reduce -

Answer 6

cavitation

Question 7

Hydraulic pumps fall into two categories; hand pumps and engine driven pumps. Hand pumps are generally only -

Answer 7

used in emergency back up systems

Question 8

A constant delivery or fixed volume pump delivers a constant amount of fluid each time it rotates, irrespective of system demand. If the pump is delivering more fluid than is required -

Answer 8

an automatic cut-out valve opens to allow fluid to return to the reservoir to avoid overloading the system

Question 9

Which type of pump:

If pressure is low, the pump output is increased automatically by a pump compensator within the pump.

Answer 9

Constant pressure or variable volume pump

Question 10

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

Answer 10

an air pump driven by compressor bleed air.

Question 11

Which type of valve:

This is effectively a one way valve. It allows air to flow in one direction but if the air attempts to reverse direction the air pressure closes the valve.

Answer 11

Check valve

Question 12

Internal leakage in a hydraulic system will cause :

Answer 12

an increased fluid temperature.

Question 13

In a modern hydraulic system, “hydraulic fuses” can be found. Their function is :

Answer 13

To prevent total system loss in case of a leaking hydraulic line.

Question 14

Hydraulic fluids of synthetic origin are:

Answer 14

purple.

Question 15

In hydraulic system, a shuttle valve :

Answer 15

allows two possible sources of pressure to operate one unit.

Question 16

Where in a hydraulic system might overheat detectors be installed?

Answer 16

At the pumps.

Question 17

The function of the selector valve is to:

Answer 17

communicate system pressure to either side of an actuator.

Question 18

The low pressure switch of a hydraulic circuit sets off an alarm if :

Answer 18

the pump output pressure is insufficient.