Midterm 2

Question 1

these are located on the side of a reservoir

Answer 1

oil level sight glass and thermometer

Question 2

the power source that drives the pump

Answer 2

prime mover

Question 3

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

Answer 3

the speed or rate at which the work must be done

Question 4

what is the function of a pump?

Answer 4

to create flow

Question 5

the ability to separate water from a liquid

Answer 5

demulsibility

Question 6

particles grinding between moving Parts is what type of where?

Answer 6

abrasion

Question 7

how do vary the GPM of a gear pump

Answer 7

vary the pump rpm

Question 8

why do hydraulic reservoirs have baffles?

Answer 8

to slow migration of fluid to aid in Cooling

Question 9

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

Answer 9

piston size and fluid pressure

Question 10

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

Answer 10

entrained

Question 11

the hydraulic fluid with the best natural lubricity

Answer 11

petroleum

Question 12

the output component on a hydraulic system

Answer 12

actuator

Question 13

gage atmospheric pressure

Answer 13

zero

Question 14

absolute atmospheric pressure

Answer 14

14.7

Question 15

a double acting cylinder moves under power:

Answer 15

in both directions

Question 16

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

Answer 16

viscosity index

Question 17

what do chemical properties of a hydraulic fluid determine?

Answer 17

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

Question 18

a single acting cylinder moves under power:

Answer 18

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

Question 19

what do additives in the hydraulic fluid prevent

Answer 19

rust and corrosion

Question 20

1 bar is how many atmospheres

Answer 20

1.01

Question 21

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

Answer 21

directional control valve

Question 22

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

Answer 22

the line terminates beneath the fluid

Question 23

how does temperature affect viscosity

Answer 23

heat - less viscous

cold - more viscous

Question 24

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

Answer 24

Bernoulli’s principle

Question 25

the best fire resistant hydraulic fluid for high temperature operation

Answer 25

synthetic

Question 26

ISO

Answer 26

International standards organization

Question 27

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

Answer 27

efficiency of a system

Question 28

how is pressure created?

Answer 28

flow is restricted or resisted

Question 29

the PSI of a pilot valve

Answer 29

75 to 100

Question 30

how is heat produced in a hydraulic system?

Answer 30

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

Question 31

what is viscosity of a fluid

Answer 31

resistance to flow

Question 32

two things that could cause a liquid to flow

Answer 32

a pump and the weight of the liquid

Question 33

what kind of valves are typical in a directional control valve

Answer 33

poppet, rotary, and sliding spool

Question 34

what principle is the operation of piston pumps

Answer 34

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

Question 35

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

Answer 35

atmospheric

Question 36

rod wiper/scraper importance and materials

Answer 36

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

Question 37

typical size of a strainers pores

Answer 37

50 microns

Question 38

oil and water mixing

Answer 38

emulsification

Question 39

psig to psia

Answer 39

psig + 14.7

Question 40

how is flow measured

Answer 40

GPM

Question 41

effects on a system with too high a viscosity

Answer 41

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

Question 42

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

Answer 42

the acutator

Question 43

what determines the speed of an actuator?

Answer 43

flow or GPM of the fluid

Question 44

1 cubic ft of fluid is how many psi?

Answer 44

0.4 psi

Question 45

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

Answer 45

pressure

Question 46

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

Answer 46

pilot to open and pilot to close

Question 47

what is a part of a restriction check valve

Answer 47

an orifice in a poppet

Question 48

describe a two-stage valve

Answer 48

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

Question 49

viscosity units

Answer 49

saybolt universal seconds (SUS) | centistokes (eSt)

Question 50

how many basic classifications of fire resistant hydraulic fluids are there

Answer 50

4

Question 51

the input component of a hydraulic system

Answer 51

pump

Question 52

how to improve cycle life in check valves

Answer 52

they have hard steel seats and poppets

Question 53

a vane type pump may have variable displacement if

Answer 53

it is of the hydraulically unbalanced type

Question 54

a hydraulic cylinder changes hydraulic power into

Answer 54

straight in-line motion

Question 55

what are 4 advantages of a hydraulic system

Answer 55

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

Question 56

what is the purpose of cylinder cushions

Answer 56

to prevent the piston from hammering the end caps

Question 57

what does a relief valve do

Answer 57

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

Question 58

the 4 primary purposes of hydraulic fluid

Answer 58

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

Question 59

directional control valves are sized by

Answer 59

the nominal size of the ports