Jan 10th Flashcards
Name some of the basic principles of hydraulics.
Liquids Have no shape of their own
Liquids are Practically incompressible
Liquids transmit applied pressure in all directions
Liquid provides great increase in work force.
How is pressure created in hydraulics.
Pressure can only be created by resistance to flow
What happens during flow across and orifice ?
Results in a pressure drop that is directly proportionate to the area of the orifice opening.
When _____ is put into a hydraulic system in the form of flow under pressure it will result in either flow or heat.
Energy
What are the main advantages of hydraulics ?
Flexibility Simplicity Compactness Economic Safety Efficiency Cleanliness
What is the PTO
Power take off
Is any of several methods for taking power from a power source (engine) and transmitting it to the hydraulic pump.
NOT A PART OF THE HYDRAULIC SYSTEM
Describe a hydraulic pump
Concerts mechanical force into Hydraulic energy (fluid power)
Does not create pressure just flow
What kind of displacement pump would you find on an open centre system and define it
Fixed displacement pump
These move the same volume of oil with every cycle
The volume is only changed when the speed of the pump is changed.
What kind of displacement pump would you find on a closed centre system and define it
Variable displacement pump
Can vary the volume of oil they move with each cycle even at same speed.
Internal mechanism varies the displacement and output
Used where pressure and flow must be maintained
Define a hydraulic motor
Works in reverse of a pump converting fluid energy back to mechanical
Ex winch, swing
Define hydraulic cylinder
Does the work of the hydraulic circuit.
What does the hydraulic reservoir do ?
Not only stores oil but also helps keep the oil clean, free of air and cool.
What do the hydraulic control valves do.
Direct the flow of oil in hydraulic systems
What is a hydraulic check valve
A simple one way valve that can be a separate component but usually is a part of another complex valve
What is a hydraulic holding valve designed for ?
Double acting cylinders which are supposed to hold pressure.
Ensures smooth decompression prior to return of the cylinder
What is the purpose of a hydraulic relief valve
High pressures can damage hydraulic components, relief valves remedy this situation when oil pressure gets too high they relive the flow by diverting oil into an auxiliary direction
What is the role of an accumulator
There to maintain a specific pressure in a closed centre hydraulic system. This allows for a smooth engagement of components when the pump is not providing full pressure due to start delay
What device measures the amount of pressure at any given section.
Hydraulic gauge
What does a hydraulic filter do
Removes contaminants from the system
What is the job of a hydraulic cooler
To remove access heat generated by energy losses in a system as well as that from external sources
How does a hydraulic swing motor work
Oil flows through the motor which turns the pinion gear, the pinion gear interacts with a gear on the turntable allowing the upper structure to swing/slew
How does a hydraulic boom cylinder work
As oil flows through the cylinder it pushes the rod out to raise the boom , reverse the flow and the boom lowers
What is the difference between single and double acting cylinders
Single uses hydraulic pressure to extend then retracts under gravity
Double acting cylinder uses hydraulic pressure to extend and retract.
