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Mechanical Theory 4 > Hydraulics > Flashcards

Hydraulics Flashcards

1
Q

What is the definition of fluid

A

A substance that will readily take the shape of its container

It is capable of transmitting power

It can be a liquid or gas

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2
Q

Hydraulic multiplication:

A =
F =
P =

A 
A = AREA of piston face
F = FORCE acting on a piston
P = PRESSURE exerted on the system      fluid
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3
Q

Explain the equation triangle for hydraulic multiplication

A

F/AxP

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4
Q

Name 8 advantages of hydraulics over electric motors

A

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 of equivalent electric motor

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5
Q

Name four disadvantages of hydraulics

A

Fire risk with mineral oil systems

Noise

Risk of contamination

Less efficient (85-95%)

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6
Q

Densi steel working mastic and pvc self adhesive tapes give off toxic gases when ignited. Where is the only place it should be used and where should it be stored?

A

On the upper deck and in the flammable store.

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7
Q

What temperature do fluorocarbon elastomer 0-rings give off toxic gases?

A

Above 300°C

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8
Q

What toxic gases are produced when fluorocarbon elastomer 0-rings are at extreme temperatures?

A

Hydrogen fluoride

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9
Q

What PPE must be worn when working with fluorocarbon elastomers?

A

Pvc gauntlets

Rubber boots

Pvc coveralls

Full face visor

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10
Q

Name two types of hydraulic fluid and what they are made from

A

Petroleum based - petroleum based oils are general purpose mineral oils.

Synthetic based - man made for specific purposes

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11
Q

The 3 oils in use are what colours, and used in what submarines/ships?

What are they called?

A

OX30 - red in colour, a synthetic oil used in hydraulic systems on board submarines

OM33 - this is yellow/orange in colour. A general purpose petroleum based hydraulic oil used in Older generation ships (T42, T22 and CVS)

OX40 - this is green in colour. A synthetic oil used in hydraulic systems on board T23s, T45s and all future projects

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12
Q

What is hydraulic fluid replaced with to prevent corrosion during upkeep periods when hydraulic oil has been removed from the system?

A

Rust Veto

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13
Q

List 6 requirements of a hydraulic fluid

A

The transmission of power (main requirement)

Fluid must flow easily through lines

It must be incompressible

Lubrication is an important requirement

Sealing properties

Cooling

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14
Q

Name 5 common causes of contamination in hydraulic oil

A

Airborne particles and moisture

Construction dirt

Dirt in new fluid

Dirt produced by wearing in new system

Dirt from human sources

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15
Q

What methods are used to reduce contamination

A

Good system design

Filtration and filter maintenance

Operation of filter and clogging indicators

Good working practices

Use guardian filter pack

Caps should be fitted to open pipework

Clean working area

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16
Q

The hydraulic system will generally have what three sets of pipework

A

Pressure supply, Return and drain.

The drain leg returns oil that has been used for cooling, sealing and lubricating

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17
Q

Name 6 types of positive displacement pumps used for hydraulic systems

A 
Internal gearwheel
External gearwheel
Vane 
Lobe
Radial piston type
Axial piston pump (using a swash plate)
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18
Q

What are axial piston pumps used on?

A

Stabilizer systems

CPP systems

Steering systems

19
Q

Define an actuator

A

Actuators convert hydraulic energy into mechanical motion.

The two types consist of linear and rotary.

Linears can be either single or double acting.

20
Q

Define an accumulator

A

An accumulator is a device in which potential energy is held under pressure. They are useful in fluid power systems to store energy and smooth out pulsations.

21
Q

Name four uses for fresh water

A

Drinking

Washing

Cooking

Cleaning

22
Q

Services provided by the fresh water system include

A

The laundry

The galley

Shower and sinks

Water heaters

Medical use

Bridge window washers

Fresh water hose reels

Machinery cooling

23
Q

Define reverse osmosis

A

The transfer of water from salt water through a semi permeable membrane into pure water

24
Q

What is the TDS of sea water

A

34,000ppm

25
Q

What is the TDS of water after desalination

A

250-300ppm

26
Q

What percentage of the water is ejected whilst purifying water

A

80%

27
Q

What is the desalinated water called

A

Permeate - made water

28
Q

What is the waste water called after desalination

A

Concentrate

29
Q

The reverse osmosis plant has two filtration stages. What does the first stage compromise of

A

A bag filter that filters down to 60 microns

30
Q

The reverse osmosis plant has two filtration stages. What does the second stage compromise of

A

A bank of two cartridge filters that filter down to 10 microns

31
Q

What type of pump does the RO plant have?

A

High pressure 3 piston positive displacement pump. (65 bar)

32
Q

How are the cushion membranes edges held together

A

Ultrasonically welded edges

33
Q

The anti scalant that is added called hypersperse is added at what rate?

A

5ppm

34
Q

Concentration control valve controls the back pressure of sea water acting on the membrane cushions. By closing the valve the back pressure is …… And the amount of permeate is ……

A

Back pressure is increased and permeate is increased

35
Q

What level is chlorine added in fresh water tanks after the membranes and when is it checked?

A

0.2ppm and daily and before embarkation.

36
Q

When will desalination not continue and where?

A

If the water is contaminated such as harbour or estuary waters

37
Q

Name the three fresh water tests

A

Chemets

Visual

Taste

38
Q

What do we use to heat up water on board ship?

A

Calorifiers

39
Q

Name the symptom of air in the fresh water system

A

“water hammer” a loud banging inside the pipes

40
Q

What colour are fresh water hoses

A

Blue

41
Q

What unit if used to measure the F in the hydraulics triangle

A

KG

42
Q

What unit if used to measure the A in the hydraulics triangle

A

Cm2

43
Q

What unit if used to measure the P in the hydraulics triangle

A

Kg/cm2

Mechanical Theory 4 (3 decks)

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