Hydraulic Accessories Fluids And Seals

Question 1

Why should a dynamic seal have leakage

Answer 1

For lubrication

Question 2

How can you determine the proper torque setting when your assembling a hydraulic system

Answer 2

Service manual

Question 3

What type of sealant should be used on tapered pipe thread in a hydraulic system

Answer 3

Liquid PTFE

Question 4

When static O-ring gaskets are used, what percentage must they protect.

Answer 4

10%

Question 5

What size of micron particles do the most damage in a hydraulic system

Answer 5

4,6,14

Question 6

What method is used to ensure you have achieved the target cleanliness code in a hydraulic system

Answer 6

Use of a particle counter

Question 7

What filter has to be rated at the relief pressure of the system.

Answer 7

Pressure line filter

Question 8

What is the recommended micron sized filter for reservoir filters

Answer 8

3

Question 9

What is the efficiency of a filter with the beta ratio of 10

Answer 9

90%

Question 10

What is the main purpose of the accumulator

Answer 10

To store pressurized hydraulic fluid

Question 11

What extra safely precaution must he used when working on a system with an accumulator

Answer 11

Depressurization completely and block out accumulator

Question 12

What type of gas could be used in a a gas accumulator

Answer 12

Nitrogen

Question 13

What is the main disadvantage of a gas or spring type accumulator

Answer 13

Can not maintain a constant pressure as they discharge

Question 14

What component in a reservoir reduces turbulence, AIDS in cooling and allows settle of dirt

Answer 14

Baffle

Question 15

What condition can occurs if a strainer on a pump becomes clogged

Answer 15

Cavitation

Question 16

What site is an open circuit reservoir compared to the capacity of the pump

Answer 16

2-3 times larger

Question 17

viscosity index (VI) of oil is defined as?

Answer 17

Stability of an oil viscosity over a temperature range

Question 18

Under what condition do you need a heater in a reservoir

Answer 18

When temp is to cold for fluid flow

Question 19

In addition to transmitting power what (4) things must hydraulic fluids do

Answer 19

Lubricate
cool
seal
flush

Question 20

What is the main cause of oxidation in hydraulic fluid

Answer 20

Heat

Question 21

List the 4 harmful products of oxidation in hydraulic fluid

Answer 21

Varnish
Gum
Sludge
Acid

Question 22

In an open circuit how much larger must the reservoir be compared to the size of the pump.

Answer 22

2 to 3 times larger

Question 23

What is a breather used for

Answer 23

It allows air flow in and out of the reservoir

Question 24

A inlet filter of a size of 100 micron is used for what?

Answer 24

100 micron filter is used to remove large contaminants

Question 25

In a water cooler (shell and tube heat exchanger) the symbols for cooling, heating or a combination of the two look like what?

Answer 25

Arrows point outward for cooling In-ward for heating And the same direction for heat and cooling

Question 26

Is a closed reservoir that's sealed from the atmospheres pressure, below or above atmospheric pressure

Answer 26

Above 1-3psi

Question 27

What micron sizes do the most damage in a hydraulic system

Answer 27

4,6,14 25/22/19 = 4u 6u 14u ``` # of Microns in a milliner sample - lower is cleaner ```

Question 28

What is the main cause of cavitation

Answer 28

Reduced inlet flow

Question 29

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

Answer 29

Measuring return flow of cylinder

Question 30

Which control system for the proportional DCV uses a linear displacement transducer to compare the actual position of the actuator to the set position

Answer 30

Closed outer loop

Question 31

What are the four basic test instruments required for trouble shooting a hydraulic system

Answer 31

Pressure gauge Flow meter Tachometer Thermometer

Question 32

To the set the speed of an actuator in a proportional DCV, what would you adjust on the amplifier card.

Answer 32

Ramp function

Question 33

If you adjust load sensing compensator on a pump what will you effect

Answer 33

Stand by pressure

Question 34

If you adjust the pressure limiting compensator on a pump what do you effect

Answer 34

Max operating pressure

Question 35

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

Answer 35

The ratio of the pilot to open check is less than the ratio of the cylinder

Question 36

Hydraulic cylinder load won't move, what is the cause of this.

Answer 36

Relief valve is set to low