Hydraulic Fluid, Cavitation, Pumps Flashcards
4 things hydraulic oil does
Transmits power
Lubricates
Cools moving parts
Seals clearances
Cavitation
Formation and collapse of air bubbles from not enough pressure holding air in the fluid, from pump creating a strong vacuum
Pseudo cavitation
Excess air being drawn into the pump and pushed into the fluid from the inlet side of the pump. Usually caused from some kind of leak
Flash point
The temperature a fluid must be heated to give off sufficient vapor to ignite.
Fire point
The temperature a fluid must be heated to burn continuously after a test flame is removed
Auto ignition
The temperature something ignites without an external flame or spark
Some causes of cavitation
Cold oil, oil to thick, or any kind of obstruction making it hard to draw fluid in causing a high vacuum.
AW
Antiwear hydraulic oil. Followed by a number. The higher the number the thicker the oil is and vise versa
2 types of hydraulic oil
Water based and synthetic
Water oil emulsion
Water and oil mix. 60% water 40% oil.
Invert emulsion
Oil carries water. 60% oil and 40% water. Less fire resistant
Emulsifier
Keeps the oil and water together.
Phase separation
The process of oil and water trying to separate from one another. Caused from high pressure and the two being squeezed apart
Phosphate ester
Synthetic fire resistant fluid. Good for high pressure, but it’s very corrosive.
Oil barrel storage
Should be put on side, and in a warm place. Or use barrel covers to keep dirt and water out if upright.
Fixed displacement pump
Always puts out same amount of fluid. Needs a relief valve to protect from being over pressurized.
Variable displacement pump
Controls the amount of fluid put into the system.
Compensator
Device used to control the pressure in a variable displacement pressure compensated pump
7 steps to set up a pump
-Block flow
-set relief valve to 150 psi
-Run compensator in
-Set relief valve to specified pressure or 250psi over
-set compensator
-lock nut everything down
-open system flow
Case drain
Extra hose going back to tank. Keeps pump lubricated
Flow meter on case drain
Allows you to check for increased flow taking the path of least resistance back to tank. Which would mean your pump is bad.
Motor
Pressure is applied to a small volume area which gives rotational torque. And exits the larger volume area
Pressure and flow
Pressure controls rotational torque and flow controls the speed
High pressure seal
Allows all motors to be used as a pump
