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Hydraulics > Midterm 2 > Flashcards

Midterm 2 Flashcards

1
Q

these are located on the side of a reservoir

A

oil level sight glass and thermometer

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2
Q

the power source that drives the pump

A

prime mover

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3
Q

what determines the GPM of the pump needed in a hydraulic system?

A

the speed or rate at which the work must be done

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4
Q

what is the function of a pump?

A

to create flow

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5
Q

the ability to separate water from a liquid

A

demulsibility

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6
Q

particles grinding between moving Parts is what type of where?

A

abrasion

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7
Q

how do vary the GPM of a gear pump

A

vary the pump rpm

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8
Q

why do hydraulic reservoirs have baffles?

A

to slow migration of fluid to aid in Cooling

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9
Q

what does the cylinders capacity to lift a load depend on?

A

piston size and fluid pressure

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10
Q

any quantity of air that is in excess of the saturation level at the given pressure

A

entrained

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11
Q

the hydraulic fluid with the best natural lubricity

A

petroleum

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12
Q

the output component on a hydraulic system

A

actuator

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13
Q

gage atmospheric pressure

A

zero

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14
Q

absolute atmospheric pressure

A

14.7

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15
Q

a double acting cylinder moves under power:

A

in both directions

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16
Q

a measurement of a fluid’s resistance to flow with a change in temperature

A

viscosity index

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17
Q

what do chemical properties of a hydraulic fluid determine?

A

how long a fluid will function before it needs to be replaced

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18
Q

a single acting cylinder moves under power:

A

in One Direction, it needs a spring or the weight of a load to go in the other direction

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19
Q

what do additives in the hydraulic fluid prevent

A

rust and corrosion

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20
Q

1 bar is how many atmospheres

A

1.01

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21
Q

a valve that selectively directs or prevents fluid flow to desired locations or circuits

A

directional control valve

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22
Q

what do lines drawn to the bottom of the reservoir mean in a schematic

A

the line terminates beneath the fluid

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23
Q

how does temperature affect viscosity

A

heat - less viscous

cold - more viscous

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24
Q

if flow is constant, the sum of kinetic energy and pressure must be constant at various points in a system

A

Bernoulli’s principle

25
Q

the best fire resistant hydraulic fluid for high temperature operation

A

synthetic

26
Q

ISO

A

International standards organization

27
Q

the ability to change energy from one type to another with minimal loss

A

efficiency of a system

28
Q

how is pressure created?

A

flow is restricted or resisted

29
Q

the PSI of a pilot valve

A

75 to 100

30
Q

how is heat produced in a hydraulic system?

A

friction in the pump motor, pump, piston, and hydraulic fluid

31
Q

what is viscosity of a fluid

A

resistance to flow

32
Q

two things that could cause a liquid to flow

A

a pump and the weight of the liquid

33
Q

what kind of valves are typical in a directional control valve

A

poppet, rotary, and sliding spool

34
Q

what principle is the operation of piston pumps

A

a piston reciprocating in a bore will draw fluid in as it is drawn from the cylinder and expel the fluid as it moves back into the cylinder

35
Q

what pressure is usually available to push a liquid into the pump inlet

A

atmospheric

36
Q

rod wiper/scraper importance and materials

A

synthetic and polymer. it keeps foreign material from entering the system

37
Q

typical size of a strainers pores

A

50 microns

38
Q

oil and water mixing

A

emulsification

39
Q

psig to psia

A

psig + 14.7

40
Q

how is flow measured

A

GPM

41
Q

effects on a system with too high a viscosity

A

high resistance to flow, increased power consumption, increased pressure drop, higher operating temperatures, difficulty separating air from fluid in a reservoir

42
Q

what is the first component to consider in the design of a hydraulic circuit?

A

the acutator

43
Q

what determines the speed of an actuator?

A

flow or GPM of the fluid

44
Q

1 cubic ft of fluid is how many psi?

A

0.4 psi

45
Q

a force exerted on a unit of area, usually expressed as pounds per square inch (psi)

A

pressure

46
Q

what are the 2 basic types of pilot-operated check valves

A

pilot to open and pilot to close

47
Q

what is a part of a restriction check valve

A

an orifice in a poppet

48
Q

describe a two-stage valve

A

a pilot operated main stage and a pilot stage that is usually either electrically or pneumatically controlled

49
Q

viscosity units

A

saybolt universal seconds (SUS)

centistokes (eSt)

50
Q

how many basic classifications of fire resistant hydraulic fluids are there

A

4

51
Q

the input component of a hydraulic system

A

pump

52
Q

how to improve cycle life in check valves

A

they have hard steel seats and poppets

53
Q

a vane type pump may have variable displacement if

A

it is of the hydraulically unbalanced type

54
Q

a hydraulic cylinder changes hydraulic power into

A

straight in-line motion

55
Q

what are 4 advantages of a hydraulic system

A

reversible while in motion, overload protection while maintaining output force, infinitely variable speed, high power in a relatively small, lightweight package

56
Q

what is the purpose of cylinder cushions

A

to prevent the piston from hammering the end caps

57
Q

what does a relief valve do

A

prevents overload of the prime mover, prevents pumps and other components from being damaged

58
Q

the 4 primary purposes of hydraulic fluid

A

transmit power, cool and dissipate heat, seal clearances between parts, lubricate moving parts

59
Q

directional control valves are sized by

A

the nominal size of the ports

Hydraulics (2 decks)

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