What is Hydraulics: Definition and 79 Discussions

Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counterpart of pneumatics, which concerns gases. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the applied engineering using the properties of fluids. In its fluid power applications, hydraulics is used for the generation, control, and transmission of power by the use of pressurized liquids. Hydraulic topics range through some parts of science and most of engineering modules, and cover concepts such as pipe flow, dam design, fluidics and fluid control circuitry. The principles of hydraulics are in use naturally in the human body within the vascular system and erectile tissue.
Free surface hydraulics is the branch of hydraulics dealing with free surface flow, such as occurring in rivers, canals, lakes, estuaries and seas. Its sub-field open-channel flow studies the flow in open channels.
The word "hydraulics" originates from the Greek word ὑδραυλικός (hydraulikos) which in turn originates from ὕδωρ (hydor, Greek for water) and αὐλός (aulos, meaning pipe).

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  1. M

    Hydraulic Entrance Loss Benefits: Fluid Flow 3K US GPM

    I am trying to determine the entrance loss benefits of changing the entrance conditions from water run-off (gravity flow) from a smooth (steel plate) surface into a rectangular channel box that is under induced suction. Currently, I believe that I am restricting water removal-flow through a...
  2. Femme_physics

    How Do I Calculate Pressure Loss in Hydraulics with Two Pipes?

    I just started hydraulics and this is the first problem I'm trying to solve. Please take that into consideration! Homework Statement Given Two Pipes Water is 50 degrees Celsius http://img31.imageshack.us/img31/9752/74467684.jpg I want to see if I understand this stuff correctly...
  3. E

    Gauge and Absolute Pressure- Hydraulics

    Homework Statement I am reading through my introductory course notes, and am given a question I don't understand how to answer. A rectangular tank contains fresh water inside it to a depth of 0.5m. The tank is 1m long and .7m wide. a) calculate gauge pressure at the bottom of tank b)...
  4. G

    Power Hydraulics: Calculate Cylinder Diameter

    hello..i m phasing a problem..i have an hydraulic circuit with pressure 72 bar and i want to find the cylinder diameter. I have that rod diameter is 15 mm and the speed of the cylinder is 4 times higher than the rod..please help me because i seraching days for this solution which i m sure that...
  5. K

    Lifting an Elephant with Hydraulics: A Physics Puzzle

    Homework Statement The 70kg student in the figure balances a 1200kg elephant on a hydraulic lift. A second 70kg student joins the first student. How high do they lift the elephant? diameter of the piston elephant is on = 2.0m diameter of the piston student is on = 0.48m The liquid inside...
  6. T

    Will Increased Distance Affect Hydraulic Elevator Performance?

    I have taken the front end of a fork lift and using it in my new house as an elevator. I am using a 5 hp 220v moter to turn a pump off a woodsplitter. This is within 4 feet of the forklift. I want to move the motor and pump away from the elevator there would now be 44 feet of 3/4 in hose...
  7. M

    Starting Hydraulics Recommendations?

    Hi, We've just started studying hydraulics at my uni. I'm finding the lecturer is going way to fast and was just wondering if anyone knows of a good hydraulics book that introduces you to the basic principles and concepts? I was in our library the other day an the books there semed to...
  8. T

    Are hydraulics the strongest way to move a robot's legs?

    hi, in the hypothetical, if you had a robot with a large leg (like a mech), would hydraulics be the only way to move the leg like muscles do? what about electric cylinders? Thank you.
  9. R

    Creating Energy with Hydraulics

    I was hoping one of you could look at this idea and tell me if it will produce a positive net-energy supply, with the help of hydraulics? Please ponder it a moment and feel free to capitalize off of it if it does. Let me pause for a moment to explain what you already know. I can lift a 5000...
  10. A

    How can I make a manual hydraulic log splitter using a lever?

    We are thinking of making a project on Hydraulic manual log splitter. But the problem is we don't know much about hydraulic principles and stuff... could somebody provide me with the link of complete tutorial for manual hydraulic machines. We wish to make it hand or foot operated using...
  11. W

    The Physics of Pneumatic Office Chairs and Soap Bottles

    How do hydraulics in office chairs work? What's the physics involved in it? What actually happens when we pull the "trigger"? Additional question: What's the physics involved in soap bottles? (the one which 'spits' soap when the "lid" is pushed)
  12. M

    Underwater low pressure water hydraulics

    I'm after a dc waterproof water pump that can handle at least 60 feet of water, around 10 gallons a minute flow rate at 50 psi. finding this combination seems to be a real problem.any ideas?
  13. B

    Learning Fluid Power Systems for University Final Year Project

    For my university final year project I'm going to be working with a spin out company who are developing a new type of hyrdualic pump. However, my knowledge of fluid power systems is minimal at best, so can someone recommend me a good textbook so i don't look like a total numpty when I start?
  14. D

    Hydraulics and the darcy weisbach formula

    I am a hydraulics student and have a question, hoping someone here could help me out. In my specific assignment i am required to determine D of a pipe without the friction factor using moody diagram and the darcy-weisbach equation. here is the exact question: A steel pipe (e=0.065mm) 4200m...
  15. S

    Pressure block/diagram in hydraulics

    a) Calculate using stress (or pressure) block method, the total force on the side of a tank that is 4m wide and 5.4m deep and contains sea water of specific gravity 1.025. b) If a 1.20m depth of oil of specific gravity 0.85 was added to the sea water in part a above, draw the new pressure...
  16. S

    How Is the Resultant Force on a Submerged Plane Calculated?

    Prove that the resultant force F on a plane surface of area A immersed vertically in a liquid of density (rho) is given by the equation: F=rho.g.A.z Where 'z' is the depth to the centroid of the plane area below the liquid surface level. I under stand how F is found using this equation...
  17. B

    How Is Hydraulic Lift Calculated in Cheerleader and Football Players Scenario?

    Homework Statement A 55kg cheerleader uses an oil-filled hydraulic lift to hold four 110 kg football players at a height of 1 m. If her piston is 16 cm in diameter, what is the diameter of the football players' piston? Homework Equations The Attempt at a Solution...
  18. D

    How Do You Calculate Static Pressure at Exit Points Using Hydraulic Principles?

    Homework Statement Hi I am trying to solve this problem.I think i have the first part sorted but the second part of the question is throwing me. Given the network of pipes shown below determine the flowrate through each pipe. Use the hazen williams formula with Ch = 100. I think I have this...
  19. S

    Suspension - undercarriage, hydraulics (diagonally springs)

    Homework Statement The problem is that I can't find how am I suppose to calculate the suspension - vibrations on the arm of a car (simple beam) that connects the chassis with the wheel, when I have a hydraulic pipe connecting the arm with the chassis. I consider, in a free body diagram, the...
  20. D

    Thermal Hydraulics: Connect with Experienced Researchers

    hi guys does anyone work on thermal hydraulics? I'm currently doing studies based on both RELAP5 and TRACE codes and i would appreciate if we can share our experiences
  21. B

    Hydraulics Question: Seeking Explanation on Self-Running Machine

    Hi about 4 months back i posted my idea for a self running machine on www.overunity.com forums. Basically i had this simple idea about trying to manipulate a hydraulic system using a quadrant shape. Sorry to post this here but I've had little feedback on overunity.com despite over 1000...
  22. R

    Hydraulics equilibrium and the straw in my drink

    Sorry for the noobie question, but I've got myself in a mental bind trying to figure out static hydraulics and why things happen the way they do. Could somebody give me an equation that shows me why the fluid level on the outside of the straw in my drink is equal to the fluid level on the...
  23. Q

    Using Hydraulics to generate electricty

    I was wondering if someone could help me here. I would like to understand how hydraulic cylinders can be used to convert mechanical movement (say the up and down motion of something for example) into electricty. I understand you probably need a motor and a genertor but I can't seem to find any...
  24. R

    Raising a weight using hydraulics

    Hi I have a weight of around 100lbs that I need to raise by a few inches. Basically what I would like is some kind of compressed-gas device that I can place underneath the weight and: 1. then trigger the gas to expand and raise the weight. 2. push down the weight to restore it to its...
  25. A

    Hydraulics instead of internal combustion engine

    i recently heard that ups is designing and testing a hydraulic system to power a torque converter for an efficient delivery system i need to know the validity of the situation and the plausibility of it being run by an electrically powered motor.
  26. 3

    Simple Hydraulics & Pressure trouble

    Im having a spot of trouble with some pretty elementary problem. A mass sits inside a tube which is pointed vertically, the mass is the same shape as the pipe ( i.e. it behaves like a piston ), but the piston diameter is less than that of the pipe. In order to lift the piston, what...
  27. E

    Electromagnetism and hydraulics

    hi, I built a crane using hydraulics to move the arm and using an electromagnet at the end of the arm to pick up and move metal objects... what other applications could use hydraulics and electromagnets?
  28. Arctic Fox

    Hydraulics for Landing Assemblies?

    Where can I find information on hydraulic parts/pumps in order to design my own landing assemblies? I'd like to see how one works in heavy aerocraft. Pictures and also links to places where I can purchase large parts, etc.
  29. brewnog

    Hydraulics - does this circuit work?

    Hello there, I have designed a machine which requires a double-acting hydraulic cylinder. I need someone to let me know if this attached circuit works, if not why not, and whether there is a better way of doing it! The fluid will return to tank for about two thirds of the time the machine is...
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