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Millwright Level 3 > Hydraulic Troubleshooting > Flashcards

Hydraulic Troubleshooting Flashcards

1
Q

The most widely used circuits in industry

A

Open loop circuit

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2
Q

This returns fluid from the case drains back to the inlet of the main pump

A

Charge pump (part of a hydrostatic drive closed loop circuit)

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3
Q

In a hydrostatic drive what should the fluid viscosity stay within

A

16 to 39 St.

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4
Q

Fluid oxidization rate

A

Above 60 C the oxidization rate doubles every 5 C

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5
Q

Size of reservoir in hydrostatic drive

A

3/4 of charge pump capacity

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6
Q

A suction filter should not create a pressure drop of more than this

A

3 psi

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7
Q

If the broken drive shaft has crystallized grainy appearance at right angles to the shaft axis it is caused by

A

Coupling misalignment

if it appears twisted off then there is overpressure in the system

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8
Q

Electrical solenoids can be either

A 
AC (120 V, large current inrush, can burn out)
or DC (little current inrush, safer, won't burn out, but slower than AC)
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9
Q

The malfunctions you must fix on hydraulic systems are all symptoms of faults of these 3 things

A

Flow, pressure, and direction of flow

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10
Q

____ affects the speed of the actuator, _______ affects the force

A

Speed, Force

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11
Q

Two types of flow meters

A

Float - Tube indicator

Turbine - Electronic device attached

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12
Q

Two types of pressure gauges

A

Compound - Gives vacuum reading as well as pressure reading

Pressure Gauge

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13
Q

Which pressure gauge is recommended for hydraulic systems

A

Pressure gauge with venting isolation valve with palm button

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14
Q

The mechanism for protecting a gauge is called

A

Snubbers

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15
Q

Max temp in a closed loop system

A

80 C

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16
Q

Device used to detect hot spots for internal leakage

A

Pyrometers or infrared sensor guns

17
Q

Device used to check the rotating speed of a motor

A

Tachometer

18
Q

A sudden increase in the particle count usually means this

A

A component is starting to fail

19
Q

This can be connected to a hydraulic system for continuous monitoring of pressure, flow, and temp

A

Multi-Function test instrument

20
Q

The two basic feedback loops in a proportional solenoid valve

A

Inner loop - Comes from a valve mounted sensor

Outer loop - Comes from an actuator-mounted sensor

21
Q

These valves operate using a mechanical feedback system and an external feedback loop

A

Servo Valve (extremely accurate)

22
Q

The difference between the position signal and the command signal

A

Error signal

23
Q

Function of a LVDT

A

Sense the spool position

24
Q

The seven steps of troubleshooting

A
  1. Talk to the operator Gather information
  2. Know the system
  3. Inspect the machine
  4. List probable causes *Isolate and repairing the trouble
  5. Test probable causes
  6. Repair the system
  7. Check for root causes Preventing future problems
25
Q

The three root causes for failures in a hydraulic system

A

Contamination
Heat
Leakage

26
Q

Why would a seal be swollen

A

Not compatible with system fluid

27
Q

How should U and V-packings be installed

A

Open side or lip facing the system pressure

28
Q

Types of coolers

A

Fluid to water
Fluid to air
Used in the system main return line, cannot take much pressure

29
Q

The most frequent cause of improper operation of a fluid to air cooler

A

Dirt blocking the flow or air

30
Q

Filter cart is also known as this

A

Transfer pump

31
Q

The two kinds of external filtering

A 
Continuous (system can remain in operation)
Batch process (more thorough)
32
Q

Can you filter oxidized fluid

A

No, additives and lubricity is gone

33
Q

What should you use to flush the system

A

Clean system fluid of the correct type

34
Q

Where should you read the system temperature

A

As close to the main return line as possible

35
Q

What does no resistance indicate in a solenoid

A

A short circuit

36
Q

Most sequence circuits require the relief valve setting to be at least ___ psi higher than the sequence valve setting

A

150 psi

Millwright Level 3 (5 decks)

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