301 A - Hydraulic Principles Flashcards
What are some characteristics of a Series Hydraulic System?
Both receive full flow Torque output of motors mounted in series will be equal to the pressure difference across them divided by the number of motors. 2 Motors have outlet backpressure of 35, inlet pressure of 14, then the motors created approximately 7 each.
What is the difference of Potential Energy in relation to a hydraulic circuit?
A Pressure Drop
How much contamination do cylinder seals allow past?
Approximately 6, 10 micron or larger particles for every square inch of rod retracted.
If a Pascal is the base unit, how many Pascals in a Megapascal or MPa?
1,000,000 Pascals in a Megapascal or MPa
What pressure is a Water Glycol Mixture limited to? Why?
1812 PSI, due to lack of lubrication ability.
What mixture of oil and water is a Water Only Emulsion?
60% Water 40% Oil
How can you check oil for oxidation?
Burnt smell, sticks to fingers
How is hydraulic system efficiency determined?
Compare Input Power to Output Power
If a Metre is the base unit, how many Metres in a Millimeter?
0.001 Metres in a Millimeter.
Why can vegetable oils not be used for Hydraulic Systems?
They oxidize too quickly past 60 Celsius
What are some characteristics of a Parallel Hydraulic System?
Flow is split equally amongst the loads (Motors) Pressure is applied separately, creating more torque.
What are the three types of Hydraulic Fluid?
Petroleum, Fire Resistant and Biodegradeable
If a Litre is the base unit, how many Litres in a Decilitre?
0.10 Litres in a Decilitre.
What are some forms of contamination in a system?
Water, Acids Metal Dirt, Rubber or Paint
What are the two states of energy?
Kinetic and Potential
What is the formula for Flow Rate?
Flow Rate = Cylinder Volume / Time
What is the formula for Area?
Pie Radius Squared Diameter Squared x 0.7854
What is the most common form of Fire Resistant Fluid?
Phosphate Ester
What are some characteristics of a Series Parallel Hydraulic System?
When a load is encountered, the system will encounter more resistance to the implement power, causing pressure to rise, then changing the system to the slower operating higher torque parallel layout. Upon no load, the system pressure will drop allowing spring pressure in the directional control valve to return the system to a high speed low torque series circuit.
What mixture are Water Glycol oil substitutes?
60% Glycol 40% Water
What are some causes of Internally generated contamination?
Component Wear Surface Fatigue Cavitation Oxidation
What is Laminar Flow?
Flow through a hydraulic system with the least pressure losses possible.
If a Litre is the base unit, how many litres in a Hectolitre?
100 Litres in a Hectolitre
What is the first recommended service interval for new equipment? Why?
100 Hours, because of production contamination.
What is the formula for Horsepower?
Horsepower = Work x Rate x Time Constant (0.167)
What temperature is a Water Glycol Mixture limited to?
60 Celsius
If a metre is the base unit, how many metres in a Kilometre?
1000 Metres in a Kilometre
What are some benefits of Phosphate Ester?
Runs at higher Temperatures Better Lubrication Fire Resistant
What is the formula for Efficiency?
Efficiency = Work X Rate X Time Constant (0.167) ——————- Efficiency
What is the formula for work?
Work = Force x Distance
What is the formula for Force?
Force = Pressure X Area
What can cause slow functions of implements?
Worn out components and high oil temperatures.
If a Gram is the base unit, how many grams are in a centigram?
0.10grams in a Centigram
What are disadvantages of Emulsions?
Decreased Lubrication Bacterial Growth Seperation Water Freezes Foaming and Contamination
What is Bernoullis Principle?
Flow and Pressure within a horizantal tube will remain constant. As velocity decreases, Pressure increases
Why is the Viscosity index important?
High Viscosity oil is too thin not giving a film to seal Low Viscosity oil is too thick not lubricating
What is backpressure?
If a resistance to flow is presented on the outlet of a circuit, the pressure will built resisting the pressure coming in to the circuit.
What are some disadvantages of Phosphate Ester oils?
Create acids when exposed to water React with Zinc Brass and Bronze Reacts with Nitrile Rubber
What is the formula for Output Power?
Output Power = Flow Rate / Pressure
What are some benefits of a Water Glycol Mixture?
Does not seperate as easily Fire Resistance Operates at lower temperatures due to glycol content.
What is the Viscosity Index of Oil?
The ability to resist changes as temperature changes.
What can oxidation in a system cause?
Pitting, loss of material.
What mixture of oil and water is an Invert Emulsion?
40% Water 60% Oil
What is turbulence in a hydraulic system?
Erratic fluid movement caused by small connectors and changes in direction.
Where are fire resistant oils commonly used?
Underground mining.
What does the government standard require for mixtures of biodegradable oils?
Between 70-80% must be able to breakdown by microorganisms within a specified time. The fluid has to be non toxic.
What is the most important characteristic of Hydraulic Oil?
Viscosity, or resistance to flow.
What are some disadvantages of Phosphate Ester oils?
Expensive Not compatible with Nitrile Rubber Seals
What are some ways contamination can be ingressed?
Faulty Air Breathers Leaking Pump Inlet Cylinder Seals
