Hydraulics

Question 1

What is the definition of a fluid?

Answer 1

A substance that will readily take the shape of its container.
It is capable of transmitting power.
It can be liquid or gas.

Question 2

What is the equation for hydraulic multiplication?

Answer 2

F = A x P
Force = Area x Pressure

Question 3

What are the advantages of hydraulics?

Answer 3

It is reliable. 
Simple and easy to understand.
Infinite speed range.
Easily reversed. 
Ability to withstand overload. 
No spark risks. 
High torque at low speeds. 
1/12 the size of equivalent electric motor.

Question 4

What are the disadvantages of hydraulics?

Answer 4

Fire risk with mineral oil systems.
Noise.
Risk of contamination.
Less efficient (85-95%).

Question 5

What are two types of hydraulic fluid?

Answer 5

Petroleum based.

Synthetic based.

Question 6

What oils are in use in hydraulic systems and where and what colour are they?

Answer 6

OX30 - Red - Submarines
OM33 - Yellow/orange - T42’s, T22’s, CVS
OX40 - Green - T23’s, T45’s, all future projects
Rust veto - used instead of hydraulic oil during upkeep periods to prevent corrosion.

Question 7

What are the requirements of a hydraulic fluid?

Answer 7

Main requirement is for the transmission of power.
The liquid must flow easily through lines.
It must be incompressible.
Used for lubrication.
Sealing properties.
Cooling.

Question 8

What are the most common causes of contamination in oil?

Answer 8

Airborne particles and moisture. 
Construction dirt. 
Dirt in new fluid. 
Dirt produced by wearing in new system.
Dirt from human sources.

Question 9

What are the methods of reducing contamination in oil?

Answer 9

Good system design. 
Filtration and filter maintenance.
Operation of filter and clogging indicators. 
Good working practices. 
Use of guardian filter pack.
Caps should be fitted to open pipework. 
Clean working area.

Question 10

What are the types of positive displacement pumps that are used in hydraulic systems?

Answer 10

Internal gearwheel type.
External gearwheel type.
Vane type. 
Lobe type.
Radial piston type.
Axial piston pump.

Question 11

What are axial piston pumps used for?

Answer 11

Stabiliser systems.
CPP systems.
Steering systems.

Question 12

What is the purpose of an acutator/motor?

Answer 12

To convert hydraulic energy into mechanical motion.

Question 13

What two types of acutators are there?

Answer 13

Linear and rotary.

Question 14

What are the two types of linear acutators?

Answer 14

Single acting and double acting.

Question 15

What is the purpose, hazards and precautions associated with denso steel working mastic and PVC self-adhesive tapes?

Answer 15

Used to prevent corrosion of hydraulic pipework.
They give off toxic gas when ignited.
Should only be used on the upper deck.
To be kept in the flammable store.

Question 16

What are O rings made of ?

Answer 16

Fluorocarbon elastomers.

Question 17

What are the hazards associated with fluorocarbon elastomers?

Answer 17

They give off toxic gasses under extreme temperature (300 degrees celcius plus).

Question 18

What gas is released by fluorocarbon elastomers?

Answer 18

Hydrogen fluoride.

Question 19

What PPE is needed when working with fluorocarbon elastomers?

Answer 19

PVC gauntlets
Rubber boots
PVC coveralls
Full-face visor

Question 20

What is an accumulator used for and which type?

Answer 20

They store energy and smooth out pulsations. Used as surge or pulsation dampener. Piston type used in hydraulic systems.

Question 21

What should you do if you come into contact with hydraulic fluids?

Answer 21

Change clothing immediately.

Skin irritation is to be checked by medical staff.

Question 22

What must flexi hoses be checked for before use?

Answer 22

Check that they are in date.

Question 23

What additives are added to oil?

Answer 23

Anti foam
Anti oxidants
Anti corrosion
Demulsibility 
Pour point depressant

Question 24

What are the three sets of pipework in a hydraulic system?

Answer 24

Supply
Return
Drain leg

Question 25

What does the drain leg do?

Answer 25

Returns oil to the tank that has been used for sealing, lubricating and cooling.

Question 26

What is the purpose of a swash plate?

Answer 26

A plate within an axial piston pump which can be moved to different angles and directions to vary the flow, pressure and direction of liquid. This removes the need for a control valve.

Question 27

What is the difference between a single acting actuator and a double acting actuator?

Answer 27

Single acting - moves one item, operated from one end.

Double acting - moves two items, operated from both ends.