Hydraulic Accessories Fluids And Seals Flashcards
Why should a dynamic seal have leakage
For lubrication
How can you determine the proper torque setting when your assembling a hydraulic system
Service manual
What type of sealant should be used on tapered pipe thread in a hydraulic system
Liquid PTFE
When static O-ring gaskets are used, what percentage must they protect.
10%
What size of micron particles do the most damage in a hydraulic system
4,6,14
What method is used to ensure you have achieved the target cleanliness code in a hydraulic system
Use of a particle counter
What filter has to be rated at the relief pressure of the system.
Pressure line filter
What is the recommended micron sized filter for reservoir filters
3
What is the efficiency of a filter with the beta ratio of 10
90%
What is the main purpose of the accumulator
To store pressurized hydraulic fluid
What extra safely precaution must he used when working on a system with an accumulator
Depressurization completely and block out accumulator
What type of gas could be used in a a gas accumulator
Nitrogen
What is the main disadvantage of a gas or spring type accumulator
Can not maintain a constant pressure as they discharge
What component in a reservoir reduces turbulence, AIDS in cooling and allows settle of dirt
Baffle
What condition can occurs if a strainer on a pump becomes clogged
Cavitation
What site is an open circuit reservoir compared to the capacity of the pump
2-3 times larger
viscosity index (VI) of oil is defined as?
Stability of an oil viscosity over a temperature range
Under what condition do you need a heater in a reservoir
When temp is to cold for fluid flow
In addition to transmitting power what (4) things must hydraulic fluids do
Lubricate
cool
seal
flush
What is the main cause of oxidation in hydraulic fluid
Heat
List the 4 harmful products of oxidation in hydraulic fluid
Varnish
Gum
Sludge
Acid
In an open circuit how much larger must the reservoir be compared to the size of the pump.
2 to 3 times larger
What is a breather used for
It allows air flow in and out of the reservoir
A inlet filter of a size of 100 micron is used for what?
100 micron filter is used to remove large contaminants
In a water cooler (shell and tube heat exchanger) the symbols for cooling, heating or a combination of the two look like what?
Arrows point outward for cooling
In-ward for heating
And the same direction for heat and cooling
Is a closed reservoir that’s sealed from the atmospheres pressure, below or above atmospheric pressure
Above 1-3psi
What micron sizes do the most damage in a hydraulic system
25/22/19
4,6,14
4u 6u 14u
# of Microns in a milliner sample - lower is cleaner
What is the main cause of cavitation
Reduced inlet flow
You have installed a flow meter in the return line of a circuit you notice the flow fluctuating as you actuate the DCV
This is due to
Measuring return flow of cylinder
Which control system for the proportional DCV uses a linear displacement transducer to compare the actual position of the actuator to the set position
Closed outer loop
What are the four basic test instruments required for trouble shooting a hydraulic system
Pressure gauge
Flow meter
Tachometer
Thermometer
To the set the speed of an actuator in a proportional DCV, what would you adjust on the amplifier card.
Ramp function
If you adjust load sensing compensator on a pump what will you effect
Stand by pressure
If you adjust the pressure limiting compensator on a pump what do you effect
Max operating pressure
In the circus you have installed a set of pilot to open check valves to lock a horizontal cylinder
While testing the cylinder becomes hydraulically locked
The ratio of the pilot to open check is less than the ratio of the cylinder
Hydraulic cylinder load won’t move, what is the cause of this.
Relief valve is set to low
