Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
27 Cards in this Set
- Front
- Back
|
list two primary factors that determine the amount of friction between 2 surfaces |
pressure between materials, roughness of the surface of the materials |
|
|
the friction between 2 surfaces can easily be reduced by placing a layer of oil based liquid, called a __ between them |
lubricant |
|
|
name two major problems that may appear if a fluid with too low of a viscosity is used in a hydraulic system |
internal wear, loss of accuracy |
|
|
name two conditions in a fluid power system that promote oxidation and general deterioration of a hydraulic fluid |
foaming, water entrained in the system |
|
|
the temperature of the fluid in teh reservoir of an operating fluid poer system is ideally between __ and __ degrees fahrenheit |
110 and 140 |
|
|
name two common ways that water can enter a fluid power system and contaminate the system fluid |
condensation on the reservoir , weather if the unit is outside, cleaning |
|
|
excessive air entrainment and foaming may be caused by a variety of hydraulic system design flaws or operational problems. name 2 typical factors |
leaks in the system, return valve below atmospheric pressure |
|
|
list two characteristics of water that make it a poor hydraulic fluid should it be used alone in a fluid power system |
evaporation, freezes |
|
|
a primary disadvantage of petroleum based hydraulic fluids is low resistance to __ which makes them unsuitable in many applications |
fire |
|
|
name two problems that are commonly associated the use of fire resistant fluids in hydrauic systems |
not environmentally friendly low lubricity |
|
|
typically the initial viscosity of a water in oil emulsion is __ than what is recommended by system manufactureres? |
higher |
|
|
which fire resistant fluid is similar to automotive antifreeze |
polyglycol |
|
|
the hydraulic fluid additives that are used to prevent mettal to metal contact in system components are called anti wear or __ agents |
extreme pressure |
|
|
improving surface tension characteristics increases the rate at which water separates from hydraulic oils and collects in the __ |
reservoir |
|
|
decreasing surface __ allows antifoaming agents to reduce the formation of bubbles and foam in a hydraulic system reservoir |
tension |
|
|
the force per unit of area required to move one molecular layer of a substance over another layer of the material is called __ visocity |
absolute |
|
|
kinematic viscosity is measure with the aid of a devive called a |
viscometer |
|
|
the system that indicates hydraulic fluid viscosity by the time it takes a 60 ml of the fluid to flow through a calibrated orifice is called the __ universal viscosity system |
saybolt |
|
|
name two major problems that may appear if a fluid with too high of a viscosity is used in a hydraulic system |
loss of energy between parts, increase in internal temperature |
|
|
name two general methods that are used to establish the lubrication and wear prevention qualitites of hydraulic fluids |
extreme pressure testing, pump loading |
|
|
list two reasons it is important to propertly handle and maintain hydraulic fluids |
save money and time fom cleaning out/ replacing fluid |
|
|
when cylinders are exposed to extreme conditions, contamination of system fluid can be reduced by using __ or __ to prevent the entry of dirt from the surfaces of the piston rods |
cylinder seal rings, boots |
|
|
the first step in testing a hydraulic fluid is to compare a sample taken from the reservoir with a sample of unused fluid of the same type nad grade using a __ inspection |
visual |
|
|
__ in the fluid of a hydraulic system is caused by forcing fluid through the system without completing work outside of the system |
heat |
|
|
what are two fundamental areas of system design and operation that must be analyzed to determine the cause of higher than desired system reservoir temperatures |
air circulation, reservoir |
|
|
the cleanliness of the fluid in most hydraulic systems is assured by the addition of specialized __ devices |
filtration |
|
|
systems that cannot maintain appropriate fluid temperatures using ambient air temperatures and appropriate reservoir, pump, control valve, and actuator designs employ specialized __ devices to control temperature |
heat exchanging |
