Hudrolic Fluid, Check Valves, Accumulators, DCVs Flashcards
What four things does hydraulic fluid do?
Transmits power
Lubricants moving parts
Cools moving parts
Seals clearances
What is viscosity
Thickness of a fluid
What does WR stand for in hydraulic fluid additives.
Wear resistant.
AW stands for?
Anti wear
EP stands for?
extreme pressure
R and O stands for?
Rust and oxidation
What are the four additives for hydraulic fluid?
WR (water resistant)
AW (anti wear)
EP (extreme pressure)
R and O (rust and oxidation)
When is hydraulic fluid most dangerous?
When atomized into atmosphere
What is flash point?
Temperature fluid must be heated to give off vapor to ignite
What is fire point?
Temperature with fluid burns and stays lit
Auto ignition is what?
Temperature fluid ignites without flame or spark
Two types of fire resistant fluids are?
Water based
Synthetic
What is invert emulsion?
Creamy white liquid made up of 60% oil 40% water
Why do you have to drain water from a tank containing hydraulic fluid?
Phase separation.
Emulsifiers break down and the water separates from oil
What does a emulsifier do?
Holds water in the oil.
What does a check valve do?
Allows flow in one direction
What kind of check valve for flow control?
Bypass check valve
When used to isolate you use what type of check valve?
Back flow check valve
What type of check valve when suspending a load and allows back flow through the system?
Pilot operated check valve
What are the three types of accumulators?
Weight loaded
Spring loaded
Hydro - pneumatic
What kind of gas do we use with a hydro - pneumatic accumulator?
Nitrogen
What three things do we use accumulators for?
Maintain pressure
Develop flow
Protect against shock
Four ways a dcv is controlled?
Manually
Mechanically
Electrically
Pilot pressure
Four centers on hydraulic dcvs?
Float center (A,B,T)
Tandem center (P,T)
Blocked (none)
Open (all)
