Hydraulic Final #2 Flashcards
Name a non-positive displacement pump?
Centrifugal
Formation and collapse of air bubbles
Cavitation
What are 2 common causes of cavitation?
1) Restriction on inlet side of pump
2) Oil is too viscous
T or F
True pump cavitation stops at the pump?
True
What is false cavitation?
Psuedo-cavitation
What is caused by too much vacuum on the inlet side of the pump?
Cavitation
What is caused by extra air being drawn into the inlet side of the pump?
Psuedo-cavitation
What are 2 reasons for psuedo-cavitation?
1) Crack on the inlet piping
2) Fluid level too low
Substance used for transmitting energy from pump to actuator in a working hydraulic system?
Hydraulic fluid
What 4 uses does hydraulic oil serve in a hydraulic system?
1) Transmits power
2) Lubricates parts
3) Cools moving parts
4) Seals clearances
T or F:
Hydraulic oil is fire proof?
False
When is hydraulic oil most dangerous?
When it’s atomized
What are the 4 hydraulic additives?
1) Anti-wear
2) Wear resistant
3) Extreme pressure
4) Rust and oxidation inhibitor
Coverts working energy into rotary mechanical energy?
Hydraulic motor
Name 3 types of hydraulic motors?
1) Vane
2) Gear
3) Piston
What are the 5 ways to identify a DCV?
1) Positions
2) Ways
3) Operated
4) Return or held
5) Center conditions
How many positions can a DCV have?
2 or 3
What is the minimum number of ways a DCV can have?
2
What are the 4 ways a DCV can be operated?
1) Manual
2) Electrical
3) Pilot
4) Mechanical
What are the 4 DCV centering conditions?
1) Float
2) Blocked
3) Open
4) Tandem
Name 4 valve sizes by ports from smallest to largest?
1) D03
2) D05
3) D08
4) D010
Allows flow in one direction only?
Check valve
Name 3 applications a check valve can be used for?
1) By-pass check
2) Isolation/ back flow check
3) Pilot operated check
Name the 3 types of accumulators:
1) Weight loaded
2) Spring loaded
3) Hydro-pnuematic
Which accumulator type is charged with nitrogen?
Hydro-pnuematic
Name 3 uses of an accumulator:
1) Develop flow
2) Maintain pressure
3) Absorb shock
Name the 3 types of reservoirs:
1) Conventional
2) Overhead
3) L-shaped
What creates a quiet zone inside the reservoir?
Baffle plate
Name 3 purposes a baffle plate serve inside a reservoir:
1) Allows fluid to cool
2) Settle dirt
3) Allows trapped air to escape
Name 2 types of fluid coolers:
1) Air cooled
2) Water cooled
What are the 2 types of flow controls:
1) Fixed
2) Adjustable
What are 4 locations of hydraulic filters:
1) Sump strainer
2) Suction filter
3) Pressure filter
4) Return filter
What are the 4 hydraulic cylinder types:
1) Single acting
2) Double acting
3) Single rod
4) Double rod
What slows the rod speed at the end of its stroke?
Cushion valve
What helps eliminate shock in a hydraulic cylinder?
Cushion valve
Name 4 pressure control valves:
1) Relief valve
2) Sequence valve
3) Pressure reducing valve
4) Counterbalance valve
What 3 pressure control valves are normally non-passing?
1) Relief valve
2) Sequence valve
3) Counterbalance valve
Which pressure control valve normally has a built in bypass check?
Counterbalance valve
Which pressure control valve is normally passing?
Pressure reducing valve
What must be added in parallel with a sequence valve to allow reversible motion?
By-pass check
Name the 2 styles of positive displacement pumps:
1) Reciprocating
2) Rotary
T or F:
Pumps create pressure?
False
What is pressure?
Force per unit area
Which pressure control valve limits system pressure?
Relief valve
Which pressure control valve allows one operation to happen before another operation?
Sequence valve
Which pressure control valve reduces downstream pressure after a valve?
Pressure reducing valve
Which pressure control valve counteracts a heavy weight on an actuator?
Counterbalance valve
What creates pressure?
Resistance to flow
What 3 things dictate the capacity of a pump?
1) Size of pump
2) Viscosity
3) RPM
Bearing for a split case pump is referred to as what?
In-between bearing
Bearing in an end suction pump is called what?
Overhung bearing
Rather than using a DCV, what is used to hold heavy loads in the air?
Pilot operated check valve
T or F:
A safety relief valve is the only thing that limits system pressure when using a fixed displacement pump?
True
What are the 2 types of packing in a pump:
1) Mechanical
2) Compression packing
Which type of displacement controls pressure at the pump?
Variable
Name the 3 types of impellers used in pumps:
1) Open
2) Semi-open
3) Closed
List the 7 steps to setting the compensator on a pump:
1) Block flow
2) Back relief valve all the way out
3) Run compensator all the way in
4) Set relief valve pressure
5) Set system pressure
6) Lock jam nuts
7) Open flow
What is the separation of oil from water?
Phase separation
What is excessive flow over the case drain an indication of?
A failing pump
How is pressure measured?
PSI
How is flow in a hydraulic system measured?
GPM
Name 2 different types of hydraulic fluid:
1) Water based
2) Synthetic
Which pressure control valve has an external bleed line back to tank?
Sequence valve
Which 2 pressure control valves have the pilot before the valve:
1) Relief valve
2) Sequence valve
Which pressure control valve has an external pilot pressure that monitors the flow rate leaving the cylinder body?
Counterbalance valve
Is a 2 position DCV spring centered or spring returned?
Spring returned
Is a 3 position DCV spring centered or spring returned?
Spring centered
Which displacement pump has a case drain to help monitor pump life?
Variable displacement
Name 2 types of centrifugal pumps:
1) Split case
2) End suction
Which hydraulic filter is located inside the reservoir and can be hard to get to?
Sump strainer
Which hydraulic filter is located just before the pump inlet?
Suction filter
Which hydraulic filter is located after the pump but before the return?
Pressure filter
Which hydraulic filter is located just before the reservoir in the return system?
Return filter
What is the most common flow control?
Needle valve
Which of the 4 ways to operate a DCV has the ability to move the biggest spool type?
Pilot operated
