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Millwright > Hydraulics > Flashcards

Hydraulics Flashcards

1
Q

How is a gerotor pump recognized?

A

Internal gear has one less tooth than external female gear

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2
Q

What does an unloading valve do?

A

Returns fluid back to tank after system pressure is reached

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3
Q

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

A

Regulator

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4
Q

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

A

10600 lbs ( pi R² )

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5
Q

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

A

The inlet is restricted

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6
Q

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

A

Tandem center DCV

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7
Q

How are filters sized?

A

Microns

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8
Q

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

A

Pressure reducing valve

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9
Q

What is the principal function of a positive displacement pump?

A

To create a partial vacuum on the inlet.

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10
Q

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

A

Flow control valve

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11
Q

Fluid power actuators convert fluid into what?

A

Motion

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12
Q

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?

A

5” (FPA Triangle)

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13
Q

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

A

1592 psi

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14
Q

In fluid power, how is pressure created?

A

A resistance to flow

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15
Q

Solid filled equilateral triangles on a schematic indicate what?

A

Flow

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16
Q

An external gear pump resembles what shape?

A

Figure 8 shape

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17
Q

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

A

Driven using timing gears

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18
Q

Pumping chambers in a gerotor pump are created by?

A

Odd number of forms between both elements

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19
Q

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

A

Increases oiling system for better efficiency

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20
Q

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

A

Fixed displacement

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21
Q

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

A

Pump not primed

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22
Q

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

A

Immediately after the actuator

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23
Q

If a pilot orifice is plugged what will happen?

A

Valve will not open

24
Q

What is the function of a sequence valve?

A

It allows one operation to occur before another

25
Q

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

A

Debree in oil

26
Q

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

A

Completely plugged vent

27
Q

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

A

Cavitation

28
Q

How many cubic inches are in one gallon of oil?

A

231

29
Q

How do you choose hydraulic tubing?

A

Material, OD, wall thickness

30
Q

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

A

Sequence Valve

31
Q

What is the principal function of a positive displacement pump?

A

To create a partial vacuum on the inlet

32
Q

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

A

a flow control valve

33
Q

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

A

A radial piston pump

34
Q

What type of hydraulic pump has a swash plate?

A

An axial piston pump

35
Q

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

A

Always be kept clean

36
Q

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

A

To prevent the returning fluid from directly entering the pump inlet

37
Q

Fluid power actuators convert fluid force into what?

A

Motion

38
Q

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

A

841 in/min

39
Q

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

A

Equally in all directions at right angles to the containing service

40
Q

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

A

Envelopes

41
Q

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

A

Spur

42
Q

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

A

In the same direction

43
Q

Lobe pump rotors must be driven by?

A

Driven using timing gears

44
Q

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

A

The shape of the cam ring surface

45
Q

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

A

Centrifugal force

46
Q

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

A

14.7 PSIA

47
Q

What function does a MPRV serve?

A

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

48
Q

Hydraulic fittings are sized with what?

A

Micron rating

49
Q

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

A

Nut ID

50
Q

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

A

Discharge valve

51
Q

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

A

Adjust cushion

52
Q

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

A

There is Aeration present

53
Q

What causes Aeration?

A

Leaking inlet

54
Q

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

A

Cavitation

55
Q

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

A

Tandem center

56
Q

A cylinder creeps slowly what is the cause?

A

Spool of DCV is leaking

57
Q

How many cubic inches are in an Imperial gallon?

A

277

Millwright (11 decks)

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