Hydraulics

Question 1

The measure of the density of a liquid is what

Answer 1

Specific gravity

Question 2

Pressure is measured in

Answer 2

Pounds per square inch PSI

Question 3

What is not needed to calculate the work a hydraulic cylinder can do

Answer 3

Power, you need pressure x piston area = force

Question 4

Pascals law states that when pressure is exerted on a confined liquid the pressure is

Answer 4

Transmitted equally in all directions through the liquid

Question 5

Bernoullis principle states that the total energy of the fluid always remains constant. Therefore when the fluid flow in a system increases the pressure must

Answer 5

Decrease

Question 6

A hydraulic fluid must do all of the following except

Answer 6

Compress easily

Question 7

Hydraulic fluid that exhibits little change in viscosity is said to have a high

Answer 7

Viscosity index

Question 8

The ability of a fluid to penetrate into the small clearance between the closely fitted parts and remain there is based on its

Answer 8

Viscosity

Question 9

The best method of controlling hydraulic fluid contamination is the use of

Answer 9

Good maintenance

Question 10

What will limit the hydraulic fluid oxidation

Answer 10

Chemical inhibitor

Question 11

The ability of a filter to remove 100% of the particles from a fluid is called its

Answer 11

Absolute rating

Question 12

When the max allowable pressure drop of a filter is reached the filter will

Answer 12

Permit particles through the medium

Question 13

Filters are used to pick up smaller contaminant particles because

Answer 13

They are able to accumulate them better than strainers

Question 14

Depth filters load up quick and thus

Answer 14

Don’t have a long service life

Question 15

Why are other surface filter media sintered or fused together used in high pressure systems

Answer 15

They are a thick mass of material which provides support to the filtering surface

Question 16

The sudden slowdown in fluid movement causes many contaminants suspended in that fluid to

Answer 16

Separate and settle to the bottom of the tank

Question 17

The baffle is used to help circulate returning fluid around the inside of the tank this also aids in what

Answer 17

Fluid cooling

Question 18

In order to permit efficient cooling of the fluid reservoir the

Answer 18

Walls should be as thin as possible

Question 19

What is used to vent the reservoir to the atmosphere

Answer 19

Air breather equipped with a 10 micofaret? Filter

Question 20

Peak hydraulic system demands are met by the use of an

Answer 20

Accumulator

Question 21

What causes hydraulic pressure

Answer 21

It’s caused by the load on the system and by the resistance of the hydraulic system to fluid flow

Question 22

Pump capacity is not rated in what term

Answer 22

PSI, they are typically rated in ,GPM

Question 23

The ratio of the actual delivery rate to the theoretical displacement is called

Answer 23

Volumetric efficiency

Question 24

What are the four major gear pump classifications

Answer 24

External, internal, axial flow or screw, and cycloidal

Question 25

Internal gear pumps are used in hydraulic systems limited to operating pressures below

Answer 25

1000 PSI

Question 26

Another type of pump commonly used in hydraulic systems is the

Answer 26

Vane pump

Question 27

Flow rate through a pipe is measured in

Answer 27

GPM

Question 28

Pressure lost in a hydraulic line depends on the

Answer 28

Flow velocity through the line

Question 29

Hydraulic lines should never be constructed of

Answer 29

Galvanized pipe, it could flake

Question 30

The safe working pressures of hydraulic piping are based on providing a safety factor of

Answer 30

6

Question 31

One disadvantage of using flexible hose in a hydraulic system is

Answer 31

They are less permanent then piping or tube

Question 32

What is used to change the direction of motion of hydraulic cylinders

Answer 32

Direction control valves

Question 33

Directional control valves are classified in several different ways

Answer 33

One is the number of paths three or four

Question 34

Most solenoids are only strong enough to open against a spring with a

Answer 34

15 pound closing force

Question 35

What kind of valves are commonly used in hydraulic systems because of the construction they are partially balanced and easy to operate in a high pressure system

Answer 35

Spoil valves

Question 36

How many primary or working connections does a three way spool valve have

Answer 36

Three

Question 37

The three position four way valve is called

Answer 37

A closed crossover valve

Question 38

A pressure relief valve is rated by its

Answer 38

Flow capacity and operating differential pressure

Question 39

The flow from the outlet of a sequence valve is at blank pressure

Answer 39

Line

Question 40

To limit the pressure to below the main part of the system you must use a

Answer 40

Pressure reducing valve

Question 41

A shock suppressor is used in a hydraulic system as

Answer 41

Protection against pressure surges

Question 42

Flow control valves used in a hydraulic system are usually positioned to

Answer 42

Meter out, regulates fluid flow on the outlet side of the actuator

Question 43

A cylinder in which the retracting stroke becomes the power stroke is called what type of cylinder

Answer 43

Pull type cylinder

Question 44

When a hydraulic cylinder is added to an existing system be sure that

Answer 44

The pump capacity is adequate

Question 45

What is the purpose of the cushioning device used with a hydraulic cylinder

Answer 45

Prevent mechanical shock

Question 46

All hydraulic pumps are

Answer 46

Positive displacement

Question 47

Motor pressure ratings vary from

Answer 47

100-5000 PSI

Question 48

The overall efficiency of a hydraulic motor is calculated how

Answer 48

Output hp divided by input hp

Question 49

A crescent shaped separator is used on some blank gear motors

Answer 49

Internal gear motor

Question 50

Gear motors are frequently equipped with wear plates to prevent

Answer 50

Internal leakage