Hydraulics Accessories, Fluids And Seals part A and B

Question 1

What does a range code tell you?

Answer 1

How clean or dirty your oil is when you first purchase it. Measure in microns

Question 2

How big is a micron?

Answer 2

One millionth of a metre

Question 3

What are the particle sizes harmful to a hydraulic system?

Answer 3

4, 6, 14

Question 4

What is the number 1 cause of oil oxidation?

Answer 4

Heat

Question 5

When should you change an oil filter with a bypass indicator?

Answer 5

When it turns yellow because some oil is bypassing the filter already and not getting filtered at all.

Question 6

Which hydraulic filter needs to be able to withstand the operating pressure of the system?

Answer 6

The pressure line filter

Question 7

What is the most efficient filter system in hydraulics?

Answer 7

Off-line filters (Kidney loop filters)

Question 8

When static o-ring gaskets are used, what percentage must they project from the mating surface?

Answer 8

10%

Question 9

What is the recommended micron size filter for a reservoir breather?

Answer 9

3 microns

Question 10

What is the main purpose of an accumulator?

Answer 10

To store pressurized hydraulic fluids

Question 11

What is the main disadvantage of a spring type accumulator?

Answer 11

They cannot maintain a constant pressure as they discharge

Question 12

The oxidation rate of petroleum based hydraulic oil doubles every 10C above?

Answer 12

60C

Question 13

Viscosity index (VI) of oil is defined as?

Answer 13

Stability of an oil viscosity over a temperature range

Question 14

What oxidation by product can cause sticky valves?

Answer 14

A brown sticky substance also known as gum and varnish

Question 15

For an accumulator, energy storage applications, should be pre charged to what percent of minimum system pressure ?

Answer 15

90%

Question 16

For an accumulator, pulsation dampening applications should be charged to what percent of normal working pressure?

Answer 16

70%

Question 17

For accumulators, shock absorption applications, what pre charge percentage of normal working pressure should there be?

Answer 17

75%

Question 18

What gas should you use to charge accumulators?

Answer 18

Nitrogen

Question 19

What is a positive seal?

Answer 19

Any seal that does not allow any leakage

Question 20

What is a non-positive deal?

Answer 20

Non-positive seals allow controlled leakage for lubrication.

Question 21

What is a static seal?

Answer 21

Static seals provide a seal between 2 surfaces that do not move with respect to each other

Question 22

What is a dynamic seal?

Answer 22

Dynamic seals must seal against a moving surface.

Question 23

A rotating mechanical seal that allows controlled leakage for flushing and cooling purposes would be classified as?

Answer 23

Non-positive/dynamic