Hydraulics Quiz Flashcards
What are the 4 DCV center conditions in hydraulics?
•Open Center
•Tandem Center
•Block Center
•Float Center
What are the characteristics of Open Center DCVs?
Zero pressure, can’t stop motion
What are the characteristics of Tandem Center DCVs?
Zero pressure, can stop motion
What are the characteristics of Block Center DCVs?
System pressure, can stop motion.
Should not be used to hold load.
What are the characteristics of Float Center DCVs?
System pressure, can’t stop motion
Why shouldn’t you use a Block Center DCV to hold a load?
Seal can begin to wear, allowing leakage through the DCV. Can lead to drifting.
What are the 3 most common DCV Mounting styles?
DO3, DO5, and DO8
How can you stop motion with a Float Center DCV?
Piloted Check Valve
Why would we use piloted check valves?
Allow free flow in 1 direction, and some flow in the other direction, when pilot pressure is achieved.
Why would we use Pilot Operated, Solenoid Controlled DCVs?
Pilot Pressure helps the Solenoid shift spools which require more pressure to shift.
What are chokes used for?
Create a delay in spool shifting in order to eliminate shock.
Do chokes control cylinder speed?
No
What are the 3 types of accumulators?
Weight Loaded, Spring Loaded, and Hydro Pneumatic
What is the most common accumulator type?
Hydro Pneumatic
How are accumulators charged?
Nitrogen
What are accumulators for?
Maintain pressure, supplement flow, and absorb/reduce shock.
What is the minimum an accumulator should be set at?
1/4 of system pressure
What percentage of the pressure needed to lift the load should you use to set the accumulator?
90%
What percentage of system pressure should you set the accumulator at for shock absorption?
50%
What components in a hydraulic system are connected directly to the main system pressure and do not create a full flow path?
•Accumulator
•Pressure Switches
•Pressure Gauges
What is 1 con to weight loaded accumulators?
Can generate shock
