Pumps, Valves And Cylinders Flashcards

0
Q

What are the two categories of hydraulic pumps

A

Non-positive displacement and positive displacement

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1
Q

The function of the hydraulic gear pump is to

A

Create oil flow

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2
Q

The most important characteristic of a non-positive displacement pump is that the inlet and outlet passages connect _________.

A

Hydraulically

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3
Q

Most nonpositive displacement pumps use what force to create flow

A

Centrifugal.

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4
Q

What’s a typical example of a nonpositive displacement pump

A

A water pump

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5
Q

Positive displacement pumps do not suffer significant flow loss under pressure. True or false

A

True

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6
Q

_________ is the volume of liquid that the pump delivers when the pump input shaft rotates one revolution

A

Pump displacement

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7
Q

Pressure is a result of

A

Resistance to flow

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8
Q

Pump displacement is expressed in what units of volume per revolution

A

Cubic inches per rev

cubic centimeters per rev

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9
Q

____ _____ refers to the amount of liquid that the pump delivers in a given period of time

A

Flow rate

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10
Q

What are the two common units of measurement for flow rate of a pump

A

Gallons per minute GPM & liters per minute LPM

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11
Q

What are the two factors that determine the amount of flow that a hydraulic pump delivers

A

The pumps displacement and the pumps input shaft speed

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12
Q

How many cubic inches are in an American gallon

A

231 in.³

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13
Q

Increasing a pumps displacement or input shaft speed increases what?

A

Pump flow rate

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14
Q

What are the two classes of efficiency used to evaluate overall hydraulic pump performance

A

Mechanical efficiency and volumetric efficiency

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15
Q

Mechanical efficiency is an expression of the amount of power required to overcome the_____ ______ ______.

A

Pumps internal friction

16
Q

The internal leakage oil sometimes called slippage or slip provides what?

A

Lubrication for the pumps moving parts

17
Q

What is the term used to express the amount of flow lost within the pump due to internal leakage

A

Volumetric efficiency

18
Q

And increased internal leakage results in decreased volumetric efficiency, slower actuator speed and _____ _____ _____.

A

Higher oil temperatures

19
Q

What rating is one of the most important readings assigned to a hydraulic pump?

A

The pressure rating

20
Q

What are the two basic types of gear pumps common in heavy equipment hydraulic systems

A

External and internal gear pumps

21
Q

What is between the faces of the gears on both External and Internal gear pumps to limit internal leakage

A

Pressure plates

22
Q

Internal leakage is an energy or power loss although some flow is required to

A

Lubricate moving pump parts

23
Q

What is a common difference between inlet ports and outlet ports

A

Typically, The inlet port is significantly larger than an outlet port

24
Q

What type of pump operates in one direction only?

A

Uni directional pumps

25
Q

What’s an identifiable external feature of a reversible gear pump?

A

Inlet and outlet ports are generally the same size

26
Q

What’s the maximum allowable vacuum at the pump inlet?

A

5”Hg of vacuum

27
Q

The pressure at the pump inlet port is affected by what two things?

A

Amount of restriction to oil flow in the pump inlet line.

the speed at which the pump is driven

28
Q

The pressure spike created by cavitation implosions can exceed approximately how much?

A

6.90GPa

Or 1 million PSI

29
Q

The Inlet of a hydraulic pump must be sealed tightly in order to prevent

A

Air from being drawn into the inlet and transmitted through out the system

30
Q

Where is the most commonly located place for a direct acting pressure release valve

A

Between the hydraulic pump and the directional control valve

31
Q

How does a direct acting pressure relief valve protects the hydraulic system from damage?

A

By limiting the maximum pressure in the system

32
Q

Full flow pressure - cracking pressure equals

A

Pressure Override

33
Q

Name three common directional control valve configurations

A

Poppet, Rotary and Spool