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. M

    Is a Torque Arm Necessary for Installing a Radial Hydraulic Motor?

    Hi, is it really needed to use a torque arm for installation of radial hydraulic motor? what if I only used its flange connection to put it in the system? is there any risk?
  2. A

    200,000 psi Hydraulic pressure vessel wall thickness?

    I'm Having a part machined with a cylinder shape approximately 14 inches in length with a cylinder hole in the center with a diameter of .930 . I have no idea how thick the cylinder wall needs to be. I have looked up and used hoop stress calculators online but I do not understand if they take...
  3. Mcchan

    Troubleshooting a Stuck Hydraulic Press Machine - Expert Tips and Solutions

    i need help. My hydraulic press machine just go up but won't come down. anyone know why?
  4. G

    Sizing hydraulic lines, SUS and velocity

    Hi, I'm trying to size up a suction line, for a positive displacement gear pump. I'm flowing 3.4 GPM. The oil I'm looking at using is Case IH Hy-tran. It has a SUS # of 208 at 100 degrees F and 47 at 210 degrees F. cSt of 40 at 40 degrees C and 6.3 at 100 degrees C. I have sized up a 7/8"...
  5. G

    Hydraulic gear pump ports and line sizing

    I am between selecting two gear pumps. One with .25 cu in at 2000 RPM or .38 cu in at 2000 RPM. In order for .25 cu into get the right flow, I will need to increase the speed to 3000 RPM. Gotta belt drive it either way. I have sized up a suction line of 7/8" I.D. that will get me a velocity...
  6. L

    Calculating Recharge and Contaminant Transport in a Confined Groundwater Aquifer

    Homework Statement The following questions apply to a confined groundwater aquifer consists of a homogeneous sandy soil with hydraulic conductivity, K, of 3 x10-2cm/sec. In the area of interest, the hydraulic head is 500 m, the aquifer length is 10 km, and the cross-sectional area of the...
  7. G

    Hydraulic cylinder speed/force

    Hi, I've been reading up on hydraulic fluid power design to design a lifting system for a loader bucket I'm building for my 20Hp tractor. I know how to calculate the force/ speed of one cylinder extending; but I am a little lost as far as using two cylinders. If I have a total weight of 2000...
  8. W

    Hydraulic Force: Input & Output of Multiple Pistons

    Most examples of hydraulic mechanical advantage display a little force on a small piston traveling a long distance to move a bigger piston a short distance with a lot of force. With the inverse, if we have an input of: 100 lbs of force on a 3" diameter piston traveling 1" the output would be 33...
  9. T

    I Confusion Over Hydraulic Gradient, L parameter

    I've come across two different approaches to quantifying what l is in the equation for hydraulic gradient Δh/L. In this first picture L is the parallel distance along the datum across the reference plane But in this second picture L is the length along the pipe Why are the two L's...
  10. T

    Vehicle's Hydraulic Braking System

    Hello, In Vehicle Braking system manufacture suggest me to use SAE 20W-40/APIGL 4/ZFTF - ML05F oil for disk brake. But i want to use ISO VG 46. So is it feasible oil?
  11. S

    Use centrifugal pump as air pump?

    I need to deliver air up to 5 meters high. I am thinking of using pump since I can find easily (no buying anything). Is it possible to deliver air using hydraulic centrifugal pump ?
  12. Q

    Problem of a tank with trapezoidal section.

    Homework Statement A deposit of 20 feet long and 10 feet high, has a width of 8 feet at the bottom and 18 feet at the top. In the bottom is an orifice an area of 24 in2 and discharge coefficient of 0.60. If the tank is full calculate the time required for the lower level 6 feet. Consider full...
  13. Q

    Problem of a tank with a trapezoidal section

    Homework Statement In the figure are the dimensions, and the question is the time in which the take will empty Area of orifice 1 cm2 Discharge coefficient: 0.447 Gravity 10 m/s2 Homework Equations [/B] Area of surface = 8x = 8 (2 H) = 16H The Attempt at a Solution . The red lines are the...
  14. PetePetePete

    Engineering How Does a Hydraulic Circuit with Variable Restriction and PRVs Function?

    < Mentor Note -- thread moved to HH from the technical engineering forums, so no HH Template is shown > Hi, I am struggling with a couple of questions and would like to check my working so far. Question 6: To explain the operation: I believe the electric motor turns the pump which draws...
  15. George Zucas

    Hydraulic Cylinder Loading Conditions

    Hello, I am working on a hydraulic cylinder application that will lift some weight that is not aligned with the axis of the cylinder. Take a look at the picture and imagine that instead of ropes there is a hydraulic cylinder fixed to the beam doing the lifting. The load creates moment since it...
  16. T

    Hydraulic Variable displacement piston Pump selection

    Hello everyone, I am designing one hydraulic system. In that system their is total 8 no of component function. When all the component work that time its take 150 Bar pressure and 140 lpm flow. but this all are all time not working together. they are hardly 4 to 5 time working together in day...
  17. T

    Human powered hydraulic exoskeleton

    I want some suggestion about designing a hydraulic exoskeleton whose input would be the kinetic motion of the body...the force exerted by body would be used to give an input to the hydraulic system which would inturn give a larger force as output in real time.for example an arm with exoskeleton...
  18. J

    Hydraulic cylinder (Shell) stresses

    Hello guys, this is my first time here take an apology if I choose wrong section of forum. I just want to know should in shell of double-acting hydraulic cylinder (as in hydraulic presses ) should longitudinal/axis stress be analyzed beside radial and Circumferential/hoop stress and take in...
  19. mrspeedybob

    Why have I never heard of hydraulic hybrids before?

    Ran across this recently... http://www.mobilehydraulictips.com/hydraulic-hybrid-vehicles-future-driving/ Peugeot apparently has a hydraulic hybrid car in development... http://www.extremetech.com/extreme/146450-peugeot-unveils-hydraulic-air-hybrid-80-mpg-car From what I've read from Wikipedia...
  20. armand

    Why are the forces in Newton's 3 laws equal, but not in hydraulic systems?

    Hi Mentor i am in little confusing about force, according Newton third law force on action and reaction is equal but according hydraulic system are not equal. https://www.facebook.com/photo.php?fbid=1749685448591067&set=pb.100006488851023.-2207520000.1429362639.&type=3&theater Thank you for...
  21. 1

    Hydraulic Pump/Motor: Can it Work as a Motor?

    hey people. literally just joined, hehehe my question is, can a hydraulic pump be used as a hydraulic motor. i have an idea and want to have it operating using hydraulics rather than having shafts and gearboxes to transfere to work. any comments welcome, good or bad, but i prefere good...hehehe
  22. O

    Psi question about a hydraulic cylinder

    Homework Statement A hydraulic log splitter with a maximum operating pressure of 3000 psi is powered by a 5 hp hydraulic engine. If the log splitter is capable of generating a maximum nominal force of 10 tons (20000 lb) what is the effective diameter of the hydraulic cylinder? What is the...
  23. W

    How can I use Pneumatic Muscles as Hydraulic Muscles?

    Hi everyone, this is my first post I was wondering how can I turn a pneumatic artificial muscle into a hydraulic one using water. http://www.instructables.com/id/How-to-make-air-muscles!/ These are the air muscles I was planning on using. What sort of pump would I need? Please be specific as...
  24. L

    Hydraulic Diameter: Calculate & Understand It

    Hi, I just confuse how to know this hydraulic diameter, would you mind to help me? hydraulic diameter is for reynold calculation then heat transfer coefficient. Thank you
  25. K

    Hydraulic motor torque for a home-built flight simulator

    I am constructing a home built flight simulator and am using hydraulic motors with a arm attached to the motor spindle for movement. I need to know how much torque I would need in the motor to lift 1000 lbs. Also I need to know how fast the motor should be to move the weight 1 foot in 2 seconds...
  26. M

    Is hydraulic jack violation of thoermodynamics

    when i use hydralick jack to lift up my car i put less energy and pick up heavey car ,so am i geting more by puting less in a hydralick system?
  27. P

    Calculating hydraulic cylinder size wind turbine tower

    Hello, I could use some help determining what size hydraulic cylinder I need to be able to tilt my turbine tower up. What I have is a 70 ft tower where the first 20 feet weigh 2500 lbs, the 2nd 20 weigh 1700 lbs and the 3rd 20 ft weigh 1000 lbs and the last 10 feet weigh 1000 lbs. For a total...
  28. D

    Hydraulic Energy: Understand w=0 & w>0

    Hi, I would like to understand what is the difference between the case when w=0 and the wase when w>0 in this device: http://imageshack.com/a/img540/3493/Ntztkk.png The arm is turning clockwise at w. The hydraulic pump is fixed to the arm. A disk at the end of the arm can turn around itself...
  29. P

    Where Did I Go Wrong with My Hydraulic Car Lift Plot?

    My plot didn't come out correctly, so I know I did it wrong. Where did I go wrong or was I even close? 1. Homework Statement The hydraulic car lift shown in Fig 1 will be used to lift a vehicle of weight W. Determine the force in the hydraulic actuator required support the vehicle as a...
  30. M

    Can I use one hydraulic pump for two identical motors?

    Hello I need guidance on selection of a hydraulic motor. Motor would be used to drive the wheel of a vehicle. Motor needs to generate a torque of 18.3Nm in order to overcome static friction and move the vehicle. And the motor needs to be small enough to be coupled with the tire (see the picture)...
  31. D

    Can a Direct Link Between Car Engine and Jet Pump Power an Amphibious Vehicle?

    So her is my predicament. I plan to convert my car to a amphibious car. Don't be negative and judgemental about it but I need help to figure out how I should power it on water. I have a 1400 lbs car. It has a 67hp engine. What I'm thinking I want to do is have a sprocket/gear attached to my...
  32. M

    Hydraulics and Hydraulic Machines

    Hi, Any good and detailed book on hydraulics and hydraulic machines ? Much grateful Need to cover topics on Water Turbine, Flow through Pipes and Head Losses with detail derivations.
  33. S

    Hydraulic Design for 275 Ton Spillway Gate - Sigamana

    am currently designing a servo motors for a spillway gate for a dam , I have some doubts on how to determine the pushing force( the force needed to drop the spillway gate at a safe rate) for a piston carrying a heavy load of 275tons at a speed of 0.4447 m/min(this speed was pre-determined by me...
  34. Feodalherren

    What are the forces involved in lifting a 1450-lb load with a hydraulic crane?

    Homework Statement The hydraulic crane is used to lift the 1450-lb load. Determine the force in the hydraulic cylinder AB and the force in links AC and AD when the load is held in the position shown.Homework EquationsThe Attempt at a Solution I don't even know...
  35. deuel18

    Can a hydraulic compression create endothermic phenomena?

    The title might be a bit confusing but I just want to know if you can recreate (partial) the system of refrigeration with hydraulic compression. So say, you have a container (cylindrical piston) filled with water, then you apply pressure. Will the water's temp increase? Then, will the...
  36. H

    Automotive Hydraulic power for a 1000 pound car for city driving

    I want to build a 1000 pound car for city driving with a 45 MPH limit. This totally something I want to do.just to say I can. But I'm a machinist with only basic engineering knowledge. My power plant will be a 16 HP OHV gas engine driving a 1800 psi pump coupled to a Bi-directional hydraulic...
  37. B. Elliott

    Assistance with locating a hydraulic flow divider

    At my shop we recently acquired an old 2-post automotive lift from the 70's. The lift has two cylinders, one for each post. The hydraulic lines were a bit hacked up when we got it and we're now in the process of trying to get it up and running again. We have it operational, but the arms are...
  38. K

    Thermal Hydraulic Calculations using NS

    Hi all I am very much a layman when it comes to Thermal Hydraulics and this may be a naive questions but here it goes... On the job, i use various codes to examine two phase flow in the core loop. Despite being vetted and validated numerous times over the course of many years (TRAC, RELAP...
  39. B

    Force and Pressure on Hydraulic System

    Rank in order from largest to smallest, the forces required to balance the the masses (in kgs) You can find the diagram and answer at this link on the third slide http://www.gwu.edu/~phy21bio/Presentations/PHYS1021-15a.pdf Equation P=F/A The Attempt at a Solution I'm really having trouble...
  40. O

    Hydraulic pedal drive system

    I was thinking about adding a pedal powered propeller to a kayak and I had an idea:Use a hydraulic pump/motor combo to simplify the design. That way I could have the pedals in front of me and easily route some hydraulic lines to a propeller in the back. I came across this gear driven...
  41. Q

    Fluid Mechanics and hydraulic lever

    Homework Statement In a hydraulic lever consisting of two ideal fluid lined cylinder/pistons with a fluid filled line coupling the two cylinders, the output force is 100 times the input force. For 1 Joule of work done on the input side, the work done on the output side is (in J):Homework...
  42. aladinlamp

    Does this hydraulic part exist? linear retractable hydraulic joint

    hi i am looking for linear retractable hydraulic joint, basically it is hydraulic cylinder with hole in the rod, it does not perform any work, it does not resist the fluid flow, it just expands and retracts as needed, it acts as a hose but its cylinder based is there something like...
  43. J

    Hydraulic oil not susceptible to temperature fluctuation

    Im having an issue with a manual pump opening an actuator. It opens fine and holds pressure until the temperature starts to drop. My question is does anyone know of any hydraulic oil that is not susceptible to condensing when temperature drops?
  44. C

    Designing a hydraulic servo system

    Dear all, For a project I'm going to design a servo system that will output an amplified hydraulic pressure, whereas the input is a force or pressure as well (not per se hydraulic). Output and input must directly connected due to the force feedback. I don't have a lot of experience with...
  45. C

    Advice and opinions on hydraulic drive buggy

    Hello Everyone, I am interested in getting some feedback and opinions on a project I have designing a 4 wheel drive buggy. The application is pretty specific and i would like it to meet the following: - max speed 30-40kms/hr - weight 800kgs - mainly operates at 0-15kms/hr - only runs 5mins...
  46. N

    Hydraulic System Solutions Cambridgeshire | Design, Supply & Install

    Can anyone recommend a company in the Cambridgeshire area that offer a full hydraulic service including bespoke design, supply, installation, testing and commissioning of hydraulic control systems and solutions and systems that have been used for standard and high risk applications including...
  47. F

    Nodal analysis of simple hydraulic system

    Hi, I'm trying to model a simple hydraulic system using python programming language and have difficulty with math. It's basically 3 tanks interconnected with pipes (see attached picture). Tanks are filled with some kind of fluid and are under different pressures (initial pressures P1, P2...
  48. P

    Solve Hydraulic Pump Homework: F1=33.5 N

    Homework Statement Piston 1 in the figure below has a diameter of 0.797 cm; piston 2 has a diameter of 4.32 cm. In the absence of friction, determine the force required on piston 1 necessary to support an object, m, with weight 983 N. (Neglect the height difference between the bottom of the...
  49. K

    Hydraulic turbine transient performance

    Hi I am having difficulty explaining to my mechanical engineering supervisors the following: When a pumped storage unit is in generation mode, synchronised to the grid and in steady state and the guide vanes/wicket gates are opened more to allow more water flow and therefore more power...
  50. J

    Pipe size and diameter connecting hydraulic pistons

    Hi everyone, In the attached diagram there are two hydraulic systems. The cylinder areas for each system are the same. The only thing that is different between the two systems is the pipe joining them, system B having a much smaller ID. Pascals law states that these two systems would act...
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