What is Hydraulic: Definition and 338 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. S

    How to Calculate Torque in a Hydraulic Brake System

    Homework Statement The area of the piston in the master cylinder is 1.8cm^2, and that of the piston in the brake cylinder is 6.4cm^2. The coefficient of friction between shoe and wheel drum is .50. If the wheel has a radius of 34cm, determine the frictional torque about the axle when a force...
  2. I

    What is the necessary force to support a 500 lb weight with a hydraulic lift?

    Homework Statement Piston 1 in Figure P9.24 has a diameter of 0.32 in.; Piston 2 has a diameter of 2.0 in. In the absence of friction, determine the force, , necessary to support the 500 lb weight. Picture http://www.webassign.net/sf/p9_24.gif Homework Equations F1=(A1/A2)F2...
  3. A

    Solving Hydraulic Lift & Friction Force Problems

    Homework Statement 1) Consider the hydraulic lift which has a smaller piston of area A1 and a larger piston area A2. Initially the two pistons are not moving. Show that in order to raise the larger piston by a distance d2, it is necessary to apply a force △F = ρg(A1 + A2)d2 on a smaller...
  4. P

    Diameter of Football Players' Piston: Calculating

    Homework Statement A 55 kg cheerleader uses an oil-filled hydraulic lift to hold four 110 kg football players at a height of 1.0m. If her piston is 16 cm in diameter, what is the diameter of the football players' piston? Homework Equations F1/A1=F2/A2 A=pi*r^2 F=mg The Attempt at...
  5. D

    Hydraulic pressure resistance

    I need to build a customized hydraulic pressure resistance tester in the lab. The idea is to measure easily but with a good reliability the resistance to hydraulic pressure (either external pressure on the water drops or the pressure caused by a column of water for example) of different paper...
  6. D

    Dealing with vacuums in hydraulic systems

    Hi, I've been trying to figure out a formula which describes the relation between the area, load and negative psig of the vacuum created in a vertical cylinder with the top port plugged and the bottom draining to tank (fig 1). I searched around for a formula describing this, and upon having...
  7. M

    Calculating Force Applied to Input Piston in Hydraulic System

    The load bearing piston in a hydraulic system as an area 50 times as the the input piston. If the larger piston supports a load of 6000N, how large a force must be applied to the input piston? Since the area is 50 times as large i used a ratio 10:50 Using the formula F2/F1 = A2/A1...
  8. R

    How fast does a hydraulic machine work?

    How fast does a hydraulic machine work? The model i am thinking of is a simple two-sided setup, where the surface areas of the two platforms are different and a tube connects them. In terms of movement of the two platforms, how fast can the machine work. I am just looking for an approximation...
  9. R

    Calculate hydraulic pump speed

    About those hydraulic devices that are used for lifting cars and such; how can you calculate the maximum speed at which those will operate?
  10. R

    Hydraulic pump and eddy current

    This kind of belongs to halfbakery.com, but it is down now. (I found on archive.org that) hydraulic pump (like the kind used to lift cars) forces and the surface areas of the two ends works by the equation F1 = F2(A1/A2). Say you had a .025 m^2 (end 1) surface on one end of a hydraulic pump...
  11. M

    Hydraulic Systems: Reasons for Continuous Pumping?

    To all: I’m studding hydraulic systems and it call my attention that in between cycles, when there is no need of pressure, the pump keeps pumping fluid at high pressure and since the processes doesn’t need it, the fluid is sent back to the tank over an over again until the processes needs...
  12. A

    Hydraulic Analogue - Mapping Electric Circuits to Fluid Flow

    The hydraulic analogue (check it out on wikipedia for an indepth explanation) compares between electric circuits and fluid flow. It maps voltage to pressure and current to water flow. I have been trying to take this analogue into applicability and use circuits from electronics and use them in...
  13. P

    Oil Hydraulic manual download link

    Hi Friends! Can anybody tell me the download link for "Sperry Vickers Hydraulic Manual" dealing (oil) Hydraulic valves, actuators, pumps etc? Or any equivalent manual from Rexroth or any. Please! Thanks & Regards. P.Ramesh
  14. C

    Multichannel Square Tube Hydraulic Diameter

    Hello, I am new to this forum. I read the thread about the water flow in a rectangular tube because I wanted to correlate what was being said into my own problem. My question I believe is very simple: I have a rectangular tube that has inner dividers, let's say that my tube has 6...
  15. J

    Design a Hydraulic Actuator: Calculate Load & Choose Nuts/Screws

    i'm a mechanical student, and given 1 assignment to design a hydraulic actuator. i need to calculate t load or force, so that i can choose the most suitable nuts and screw to assembly it. do u all have those kind of drawing and the formulas for calculation? please help! it's urgent..
  16. wolram

    Can a Hydraulic Stepper Motor Step 90 Degrees in 25 Milliseconds?

    Is there such a thing? i have had a search but found nothing, i can think of a way that one would work, but i need one that can (step) 90 degrees in 25 milli seconds and hold possition until the next step is called for. anyone that can help will be rewarded with one of my fantastic chili cakes.
  17. N

    Can Anyone Explain the Volumetric Tube Construction on a Hydraulic Bench?

    Hi guys, hope all are fine. i m new here and don't know much about the rules. well according to the question i have, i thought its the right place. i ll never mind if it is moved. anyways today i studied the simple laboratory hydraulic bench... i got struck in the part where plunger is...
  18. H

    Hydraulic hysteresis phenomenon

    I have the following unexplained phenomenon: (please excuse incomprehensible expressions I´m not a native speaker) Experimental setup: A 6 meter long measurment pipe is filled with a hydraulic fluid and has a square cross section (30mm²). The fluid in the pipe is pressurerised to 40 bar...
  19. wolram

    Can Electro Hydraulic Valves Revolutionize Cam Shaft Engines?

    The auto industry will be using this method to contol inlet and exhuast valves, i think 6000 rpm is the limit so far with a 48v (coil), this system has many advantages ie variable valve timing/ dwell, what are the limitations of this idea and could it be retro fitted to cam shaft engines?
  20. wolram

    Hydraulic Engine: Can It Work?

    Imagine a bar, say 3inches dia by 15inches long, the bar is turned down to 1inch dia 3inches in for 3inches, and again at 9 inches for three inches, this forms 3, connected (pistons), this piston assembly is enclosed in a cylinder the outer pistons are moved by internal combustion using the 2...
  21. V

    Fluid Mechanics: Hydraulic Lift

    Hi, I have here a problem that I've been working on, and am not sure if I've gone about it correctly. The method I chose seems too simple, and I was wondering if someone could go over the answer that I've found, and let me know if I'm doing this right.The problem: The piston of a hydraulic...
  22. F

    Hydraulic Jack Question: Calculating Piston Movement for 2000 kg Car

    A 2000 kg car is raised 1.5 meters high on a hydraulic jack, which has a large piston with a diameter of 30cm. The small piston has a diameter of 5cm (btw the reservoir is filled with oil) d) When the car is raised by 1.5 m, what distance will the small piston move? Is it simply that you have...
  23. H

    Pressure, force, hydraulic lift problem

    A hydraulic lift has two connected pistons with cross-sectional areas 25 cm2 and 630 cm2. It is filled with oil of density 690 kg/m3. I've found that approx. 63.5 kg of mass must be placed on the small piston to support a car of mass 1600 kg at equal fluid levels. but then it asks...
  24. H

    Pressure/force hydraulic lift problem

    A hydraulic lift has two connected pistons with cross-sectional areas 25 cm2 and 630 cm2. It is filled with oil of density 690 kg/m3. I found that about 63.5 kg of mass must be placed on the small piston to support a car of mass 1600 kg at equal fluid levels. But then it asks... With...
  25. E

    More Information I'm Sending With A Diagram - For The Hydraulic System

    Hi ... I attached with this text letter the mechanica system diagram that including or working by Hydraulic unit ... Its for holding about 8 tons , Metal Sheet's Coil . So I asked about How To Choose The Suitable Pump For This System . Will Be Thankfull For Your Help ... And Also For...
  26. S

    Hydraulic Damping Information Needed

    1st of all - Hi everyone, this looks like a great resource, hopefully i'll be a frequent visitor! Anyway, the reason for this post is to findout if anyone knows of any texts concerning the more practical (design) side of hydraulic damping used in suspension systems. Im at uni in England at...
  27. R

    Shear Forces Explained: Hydraulic Jump

    Please, say me what are shear forces. I've been looking for it because I was studying a phenomenon called hydraulic jump. In this example, are these forces caused by the cohesion forces?
  28. E

    Hydraulic Calculations: Pressure, Pumps & Pistons

    Hi ... Want to know about " How I can calculating ... Or ... Using Wich Formula " that is making me able to finde the relationship between the Haudraulic Pump Pressure and the Piston Pressure .? on what i should depend when i want a piston and a hydraulic pump For Example : I have a...
  29. S

    Hydraulic piston/ram diagrams or schematics?

    Can anyone lead me to some good hydraulic piston/ram diagrams or schematics? thank you
  30. H

    Pressure difference in a hydraulic system?

    Is there any difference in pressure in a pressurized tank/piston filled with a liquid between the bottom of the tank/piston and the top of the tank? My problem is that Pascal’s law states that the pressure exerted on an enclosed fluid is transmitted undiminished throughout the fluid and acts...
  31. J

    How do hydraulic launch systems achieve such high speeds on roller coasters?

    Hi, I am a young 19 old student engineer soon to begin university after a summer break. As I have a love for thrill and engineering advancements I would very appreciative if you can help me with my request. Basically, having followed the progression of the rollar coater launch...
  32. P

    Project: Hydraulic Jump or Ball Spin

    These are the problems I have to choose between for a school project entering a competition. There are other problems but these are the ones I'm torn between. Hydraulic jump When a smooth column of water hits a horizontal plane, it flows out radially. At some radius, its height suddenly...
  33. F

    Help Solve Hydraulic Problem Involving Spring and Rock

    hydraulic problem, need help! a hydraulic chamber in which a spring (spring constant = 1456 N/m) is attached to the input piston, and a rock of mass 39.4 kg rests on the output plunger. The piston and plunger are at the same height, and each has a negligible mass. By how much is the spring...
  34. M

    Calculating Height Difference h of Hydraulic System Pistons

    In a hydraulic system the piston on the left has a diameter of 4.5 cm and a mass of 1.7 kg. The piston on the right has a diameter of 12 cm and a mass of 2.5 kg. If the density of the fluid is 750 kg/m3, what is the height difference h between the two pistons? can someone please help me with...
  35. BasketDaN

    Hydraulic Seals @ 25,000+ psi?

    I'm unable to find a hydraulic seal with a maximum operating pressure any greater than 11,000 psi, and that was a specific type of "vee packing." Does anybody know of a type of seal that can withstand more?
  36. R

    Hydraulic double-acting pumps

    Will u please help me in telling me how do hydraulic doble-acting pumps work EXACTLY and the explanation of the spools function.
  37. Juntao

    Solve Mass & Height of Hydraulic Lift w/ Car & Person

    A hydraulic lift has two connected pistons with cross-sectional areas 25 cm2 and 420 cm2. It is filled with oil of density 730 kg/m3. a) What mass must be placed on the small piston to support a car of mass 1000 kg at equal fluid levels? b) With the lift in balance with equal fluid levels...
  38. ShakeWell

    Calculating Force Needed to Support an Object with Hydraulic Press

    Ok, it's a two part question, i did the first part with no problem, which is how much force it takes to hold an object on the other end up, knowing the diameters and the mass of the object, i just used F1/A1 = F2/A2. Now, the 2nd part asks how much force is needed to support the object at a...
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