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List 3 importan considerations when alanlyzing a hydraulic circuit.
1- Safty operation
2- Prerformance of desired function
3- Efficiency of operation
Purpose of a regenrative circuit
1- Is used to speed up the extending speed of a double acting hydraulic cylinder.
What is meant by an air over oil system
1- A system that used pressurized compressed air to eliminated sthe need for a costly hydraulic pump and tank unit.
What is a mechanical hydraulic servo system?
1- Is a system that messure its own outpout and forces the output to quickly and accurately follows a comand signal. Example: power-steering system in a car
Purpose of a check valve?
1- is to permit free flow in one direction and prevent any flow in the opposite direction.
Flow velocity recomended for the discharge side of a pump.
1- Recomended is 4 ft/s in order to prevent excesively low suction pressures and resluting pump cavitation.
Flow velocity recommended for the Inlet side of a pump
1- Recomended 20 ft/s in order to prevent turbulent flow and the corresponding excessive head losses and elevated fluid temperatures
Why conductors and fittings should no be copper?
1- Because coppers promotes the oxidation of petroleum oils.
Know four primary types of conductors
1- Steel pipes
2- Steel tubing
Three factors that should be considered when installing flexible hoses?
1-Provie some slack to allow for shrinkage or expansion.
2- Use brackets and clamps to keep hoses in place
3- Provide enough hose for a wide radius curve
Four criteria by which the size of a reservoir is determined.
1- To allows for dirt and chips to settle to the bottom
2- To allows entrained air to escape from oil.
3- To hold all the oil that might drain into the reservoir from the system
4- It should have adequate air space to allow for thermal expansion of the oil.
Three basic types of acumulators
1- Separetor type
2- Non- separetor type
3- Pisto acumulator type
Three aplications of acumulators
1- An auxiliary power source
2- A leakage comensator
3An emergency power source
Diference between static and dynamic seal
: are used between mating parts that do not move relative to each other.
are assembled between mating parts that move relative to each other.
Four tpes of materials used of seals.
Two types of flow-measuring devices
1- Pressure gages
Describe an intesifier
A pressure intesifier is used to eliminate the need for a high-pressure/low-flow pump.
Five most common causes of failure in a hydraulic system
1- Clogged or dirty oil filters
2- Inadequate supply of oil in the reservoir
3- Leaking seals
4- Loose inlet lines
5- Incorrrect type of oil
Define Flash point, Fire point and Autogenous ingnition temperature.
: the temperature at which the oil surface gives off sufficient vapors to ingite when a flame is passed over the surface
the temperature at which the oil will release sufficient vapor to support combustion continuously for five seconds when a flame is passed over the surface.
Autogenous ignition temperature
: The tempreture at which ignition occurs spontaneously.
Disadvantages of fire-sesistant fluids
1- low viscosity
2- incompatibility with most natural or sinthetic rubbber seals
3-and high cost
Difference between a filter and a strainer
: is to retain by some porous medum, insoluble contaminants fro fluids
: are constructed of a wire screen that rerely contains openings less than 100 mesh.
Four things that can cause a noisy pump
1- Air entering pump inlet
2- Excessive oil viscosity
3- Dirty inlet strainer
4- Excessive pump speed
Four things that can cause low or erratic pressure
1- Air in the fluid
2- Pressure relief valve set too low
3- Leak in hydaulic line
4- Defective or worn pump
Four things that can cuse NO presure
1- Pump turning in wrong direction
2- Rupture hydraulic line
3- Low oil level in reresvoir
4- Broken pump shaft