Hydraulics

Question 1

How is a gerotor pump recognized?

Answer 1

Internal gear has one less tooth than external female gear

Question 2

What does an unloading valve do?

Answer 2

Returns fluid back to tank after system pressure is reached

Question 3

In a fluid system what is used to maintain a constant pressure?

Answer 3

Regulator

Question 4

What is the maximum load in pounds that can be moved with a setting of 1500 PSI and a cylinder bore of 3”?

Answer 4

10600 lbs ( pi R² )

Question 5

If a non positive centrifugal pump delivers lower than required flow, what is the most likely cause?

Answer 5

The inlet is restricted

Question 6

A pressure gauge reads 0 in a hydraulic system. What is the reason?

Answer 6

Tandem center DCV

Question 7

How are filters sized?

Answer 7

Microns

Question 8

What is a type of hydraulic valve that is normally open?

Answer 8

Pressure reducing valve

Question 9

What is the principal function of a positive displacement pump?

Answer 9

To create a partial vacuum on the inlet.

Question 10

What type of valve controls a system GPM (gallons per minute)?

Answer 10

Flow control valve

Question 11

Fluid power actuators convert fluid into what?

Answer 11

Motion

Question 12

With a pressure of 950 PSI and a load of 7.5 tons, what must the bore of the cylinder be if we add a 10% safety factor?

Answer 12

5” (FPA Triangle)

Question 13

Determine the maximum pressure required using a 2” diameter cylinder moving a load of 5000 lbs?

Answer 13

1592 psi

Question 14

In fluid power, how is pressure created?

Answer 14

A resistance to flow

Question 15

Solid filled equilateral triangles on a schematic indicate what?

Answer 15

Flow

Question 16

An external gear pump resembles what shape?

Answer 16

Figure 8 shape

Question 17

The eternal seal of an internal gear pump is driven using what?

Answer 17

Driven using timing gears

Question 18

Pumping chambers in a gerotor pump are created by?

Answer 18

Odd number of forms between both elements

Question 19

Some pistons have grooves cut in the diameter with no lead. The function of these grooves are what?

Answer 19

Increases oiling system for better efficiency

Question 20

If a swash plate in an axle piston pump is not adjustable, the pump is what?

Answer 20

Fixed displacement

Question 21

If a new pump will not deliver flow, what is the 1st thing to check?

Answer 21

Pump not primed

Question 22

The term meter out means that the flow control valve is located where?

Answer 22

Immediately after the actuator

Question 23

If a pilot orifice is plugged what will happen?

Answer 23

Valve will not open

Question 24

What is the function of a sequence valve?

Answer 24

It allows one operation to occur before another

Question 25

If a pump has worn impellor tips, what is the cause?

Answer 25

Debree in oil

Question 26

A closed hydraulic tank starts to cave in. What will cause the condition?

Answer 26

Completely plugged vent

Question 27

What causes vibration to occur on the inlet line of a pump?

Answer 27

Cavitation

Question 28

How many cubic inches are in one gallon of oil?

Answer 28

231

Question 29

How do you choose hydraulic tubing?

Answer 29

Material, OD, wall thickness

Question 30

What type of valve allows one operation to occur before another?

Answer 30

Sequence Valve

Question 31

What is the principal function of a positive displacement pump?

Answer 31

To create a partial vacuum on the inlet

Question 32

What type of hydraulic valve is used to control the GPM (Gallons per minute) of a pump?

Answer 32

a flow control valve

Question 33

What type of hydraulic pump is used to handle high viscosity fluids?

Answer 33

A radial piston pump

Question 34

What type of hydraulic pump has a swash plate?

Answer 34

An axial piston pump

Question 35

For fluid to properly function over long periods of time, it must be what?

Answer 35

Always be kept clean

Question 36

The function of a baffle plate in a hydraulic tank is what?

Answer 36

To prevent the returning fluid from directly entering the pump inlet

Question 37

Fluid power actuators convert fluid force into what?

Answer 37

Motion

Question 38

Calculate the retract speed of a cylinder with a 2.5" bore and a rod diameter of 1" with a supply of 15 GPM

Answer 38

841 in/min

Question 39

Pascals law States that when pressure is applied to fluid at rest in a confined space, force is transmitted how?

Answer 39

Equally in all directions at right angles to the containing service

Question 40

In a fluid power directional control valve symbol, the squares are called what?

Answer 40

Envelopes

Question 41

The gear teeth on an external gear pump are what type?

Answer 41

Spur

Question 42

The gears of an internal gear pump rotate in what direction?

Answer 42

In the same direction

Question 43

Lobe pump rotors must be driven by?

Answer 43

Driven using timing gears

Question 44

The difference between an unbalanced and a balanced vane pump is what?

Answer 44

The shape of the cam ring surface

Question 45

The most efficient way to maintain contact of vanes to the cam ring surface is by what?

Answer 45

Centrifugal force

Question 46

The amount of pressure available to create a volume of delivery from a positive displacement pump is what?

Answer 46

14.7 PSIA

Question 47

What function does a MPRV serve?

Answer 47

Safeguard for the pump, will not allow pressure to exceed the setting.

Question 48

Hydraulic fittings are sized with what?

Answer 48

Micron rating

Question 49

What determines the length of a flare on a hydraulic fitting?

Answer 49

Nut ID

Question 50

What is the last valve to open when starting a pump?

Answer 50

Discharge valve

Question 51

A cylinder hammers back to the bottom on retract. How is this condition fixed?

Answer 51

Adjust cushion

Question 52

A hydraulic pump is severely worn out. What is the most likely cause?

Answer 52

There is Aeration present

Question 53

What causes Aeration?

Answer 53

Leaking inlet

Question 54

Erratic and excessive noise in a lobe pump is caused by what?

Answer 54

Cavitation

Question 55

What type of directional control valve center holds a load and dumps fluid back to the tank?

Answer 55

Tandem center

Question 56

A cylinder creeps slowly what is the cause?

Answer 56

Spool of DCV is leaking

Question 57

How many cubic inches are in an Imperial gallon?

Answer 57

277