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
The three root causes for failures in a hydraulic system
Contamination Heat Leakage
26
Why would a seal be swollen
Not compatible with system fluid
27
How should U and V-packings be installed
Open side or lip facing the system pressure
28
Types of coolers
Fluid to water Fluid to air Used in the system main return line, cannot take much pressure
29
The most frequent cause of improper operation of a fluid to air cooler
Dirt blocking the flow or air
30
Filter cart is also known as this
Transfer pump
31
The two kinds of external filtering
``` Continuous (system can remain in operation) Batch process (more thorough) ```
32
Can you filter oxidized fluid
No, additives and lubricity is gone
33
What should you use to flush the system
Clean system fluid of the correct type
34
Where should you read the system temperature
As close to the main return line as possible
35
What does no resistance indicate in a solenoid
A short circuit
36
Most sequence circuits require the relief valve setting to be at least ___ psi higher than the sequence valve setting
150 psi