Hydraulic System Components Reservoir Filters Hoses And Coolers Flashcards
The quality of the hydraulic oil will depend on how well the liquid will:
- Prevent rust
- Prevent the formation of sludge varnish and gum
- Retain its stability for an acceptable period Of time
- Maintain its this viscosity over a wide temperature range
- Prevent corrosion and pitting
- Allow water to settle out and be compatible with gaskets and seals
The power required to force the fluid through the lines and the system components is simply a power loss that shows up as what?
heat
What is viscosity?
Viscosity of a liquid is a measure of its internal resistance to flow
What measures the force per-unit area required to move two parallel surfaces that are separated with a given film thickness of oil?
And what is the common unit used for this measurement?
Absolute viscosity
Centipoise (cP)
What measures the amount of time required for a given volume of oil to flow through a capillary tube and what is the unit of measure?
kinematic viscosity
Centistoke (cSt)
What measures the amount of time required for a given quantity of oil to flow through a standard orifice while being held at a specific test temperature and what is the unit of measure?
Relative viscosity
Saybolt Universal seconds (SUS)
What device is commonly used to measure relative viscosity?
Saybolt viscometer
What does the pour point of hydraulic oil refer to?
The lowest temperature at which oil will flow
When the clearance between the moving parts is sufficient to allow the film of oil two completely separate them this condition is called?
Full film lubrication
Minute surface imperfections are known as what?
Asperities
What is the most significant factor that influences the degration of oil?
Oxidation
The rate of hydraulic oil oxidation depends on:
The amount of air the oil is exposed to
The temperature of the oil
The chemical makeup of the oil
The rate at which hydraulic oil oxidizes will double with every 10°C increase in temperature above ……?
60°C
What are the major functions performed by the hydraulic reservoir in a hydraulic system?
- Hold the system oil supply
- Cool the oil
- Allow Air and contamination to separate from the oil
The process of allowing solid contamination to settle out of the oil is known as what?
Sedimentation
What are the processes that condition the hydraulic oil while in the hydraulic tank before it re-enters the system?
De-aeration and sedimentation.
Vented hydraulic reservoirs allow atmospheric pressure to act on the surface of the oil.
True or false?
True
Another commonly used method of pressurizing a hydraulic reservoir is to use a pressure cap on the filler. What is the approximate air pressure that the relief holds in the reservoir?
10-15psi
69-103kpa
As hydraulic pressure increase, internal clearances are reduced, to control___________
Internal Leakage
Internal clearances in low pressure hydraulic components run about (Microns)
10 to 20 Microns (a micron is one millionth of a meter or 0.000039 in)
Internal Clearances of a high pressure components run at how many microns?
5 Microns
Reducing internal clearances also reduces the thickness of the ____ ______ that lubricates moving parts.
Oil Flim
It is estimated that approximately ____ of hydraulic systems failures are caused by poor hydraulic oil conditioning.
80%
Solid Contamination in the hydraulic oil interfere with system operation by? (3 Answers)
- Restricting or plugging orifices and small passages
- forming sludge that inhibits cooling and sticks moving parts
- affecting the lubricating ability of the hydraulic oil resulting in damage to precision surfaces of components parts
Contamination in hydraulic oil originates from three sources?
- Built in contamination
- Ingressed contamination
- Internally Generated Contamination
Contamination usually takes the form in these 12 forms
burrs, chips, dirt, dust, fibers, sand, moisture, sealants, welding splatter, paints, rust and flushing solutions.
Ingressed contamination refers?
to contamination that is introduced to the system when it is being serviced
Internally generated contamination is a result of particles being removed from the?
internal surfaces of the hydraulic system components
When working on or around hydraulic systems, remember the following.
- The filtration system cannot do it all.
- Dirt is everywhere
- The Cleaner your work habits, the longer the service life of system components
Full-Flow type filters?
Will receive and condition the full flow rate of the pump
Course filtration devices, often called strainers are usually made of and are rated by?
- Woven wire screen
2. mesh or sieve number
whats a microns measurement?
one millionth of a metre or 0.000039”
What are the four types of filter rating?
- Filter Rating
- Absolute Rating
- Nominal Rating
- Beta Rating
Strainers are most commonly used in the?
Pump Inlet line
pressure line filters are installed downstream of the pump and so they must be able to withstand ___ _______ _______?
Full system pressure
Filter Bypass devices and restriction indicators have to important qualities?
- Oil Viscosity
2. Filter Media Permeability
What are the three types of hydraulic conductors (system plumbing) used?
- Steel Pipe
- Steel Tubing
- Hydraulic Hose
How do you measure these types of pipe
- Pipe
- Tubing
- Hydraulic Hose
- ID
- OD
- ID
Joint Industrial Council (JIC) are used on flare angles of?
37 Degrees (used more in hydraulic systems)
Society of Automotive Engineers (SAE) are used at angles of?
45 Degrees (used more in air brake systems)
What 3 things determine what the hydraulic hose is intended for?
- System Pressure
- compatibility with hydraulic oil
- the environment the hose will be in
List four functions of hydraulic oil?
- Transmit Power
- Lubricate moving parts
- seal close fitting parts
- cool the system
The term viscosity refers to an oil’s
Internal resistance to flow
Viscosity index refers to
the amount that the oil’s viscosity changes with temperature
boundary lubrication refers to the condition where
minute imperfections on the surfaces of moving parts are in contact.
Three factors that will determine how quickly hydraulic oil with oxidize are.
- the amount of air that the oil is exposed to
- the oil temperature
- the chemical make up of the oil
The most important consideration when selecting a hydraulic oil is
Manufacturers specifications
3 functions of hydraulic oil reservoir are?
- Hold the system oil supply
- cool the oil
- allow the air and contamination to settle out of the oil
Pressurized reservoirs are used in applications where
the pump inlet line may not otherwise be filled with oil.
the greatest amount of component wear is caused by contamination that is
the same size or smaller than component internal clearances
the filtering device most commonly used in the pump inlet line is
100 mesh strainer
hydraulic oil coolers are usually connected in _____ in the system _______line.
series/return
