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

    Flow rate vs pressure relationship in a hydraulic cylinder

    Hi all, I need to model an hydraulic cylinder with simulink and to control it according to some rules. What I don't understand is to find a relationship between the flow rate and pressure inside it. Any suggestion is appreciated. Thanks
  2. R

    Hydraulic Analogy for Counter-EMF ?

    I'm trying to get my mind around counter-emf. Is there a good analogy for counter EMF in either hydrology or mechanical examples ? I've read the textbook descriptions. Likewise, I wonder if there are analogies for the phenomenon of Hysteresis.
  3. R

    Good resources for Hydraulic Actuators?

    I want to do some research on Hydraulic actuators, Hydraulic motors, etc. Anybody know of any good books on the subject? Thanks!
  4. F

    Hydraulic motor efficiency conundrum

    Hello, I'm trying to compare efficiency of different hydraulic motors by looking at unit of output per unit of input, viz: \frac{rpm × torque}{pressure × flow} I'm a bit flummoxed by one set of motor specs, for Eaton Duraforce motors, which is attached below. these motors seem to...
  5. N

    How does the compressibility of hydraulic fluid affect force?

    If an inert gas is used to force piston with a Pressure say P (Assume the volume of gas to be sufficiently large). I would like to know the following: (consider piston to be horizontal) 1) If say one puts a small volume of a hydraulic fluid in front of the piston. Keeping the same pressure of...
  6. F

    Question about hydraulic analogy

    Hello there; I am having a conceptual problem with the hydraulic analogy (a collection of similarities between electrical circuits and piping systems). It specifically has to do with the topic of pressure and voltage drops. The hydraulic analogy claims that pressure drops act like voltage...
  7. B

    Lifting a car using a hydraulic lift

    1. The hydraulic lift at a repair shop is filled with oil. The car rests on a 25-cm-diameter piston. To lift the car, compressed air is pushed down on the 6-cm-diameter piston. a) What air-pressure force will support a 1300kg car level with the compressed air piston? b) How much must the...
  8. siddharth23

    Calculations for LMP for certain RPM of hydraulic motor

    If I want the output of a hydraulic motor to be of a specific RPM, then knowing the pressure of the oil in the circuit, how does one calculate the LPM of the pump corresponding to that RPM?
  9. A

    Hydraulic Jack, Automatic 12 volt DC - College Project

    Hello Frnds, I am presenting my engineering final year project. It is a 12 volt DC hydraulic jack. This jack is made to lift light motor vehicles and light commercial vehicles. Its capacity can be increased by changing some parameters. The project consists of a 12 volt DC...
  10. S

    How do I size a hydraulic motor to fit a 12 propeller to move water?

    How do I size a hydraulic motor to fit a 12" propeller to move water? I have a 35 HP diesel motor direct driving a hydraulic pump producing 16 GPM at 2000 psi. The hydraulic pump would be connected with hoses to a water pump inserted in a pipe. I want to design/build a water pump using a...
  11. J

    Efficiently Bend 4 Feet of Mild Steel with a Hydraulic Press Brake

    Hi all, I am designing a Hydraulic press brake to air bend up to 4 feet of 1/8 in mild steel. I know it will take 11 tons of force per foot of material, 44 ton to do the trick. A 60 ton jack will cost over $1000, where 3-20 ton jacks are $40 each. My question, if I evenly space the 3 20 ton...
  12. P

    Understanding the Viscosity of Glycerine and Oil in Hydraulic Brakes

    Viscocity of glycerine is high than that of oil then why it can't be used in hydraulic brakes..?
  13. P

    Seepage, Velocity, Hydraulic Conductivity

    Homework Statement Hi there I am doing a mine engineering degree by correspondence. The lecture notes that I have calculating seepage and velocity etc is not very helpful and other then discussing darcys law and other concepts does not go through the formulas. My lecturer has gone on...
  14. D

    How much force is 5T of pressure exerted by a hydraulic ram?

    Homework Statement How much force is 5T of pressure exerted by a hydraulic ram? Homework Equations P= F/A Hydraulic Ram F1/A1=F2/A2 The Attempt at a Solution 5KN ?
  15. D

    How many hydraulic rams do I need to prevent wall collapsing ?

    Homework Statement rectangle wall with 3m height, 20 length, 6.0m width. Rectangle filled with water. The Attempt at a Solution I've calculated the force acting on the wall to be: 1766 KN I have a hydraulic ram exerting 5 tonnes of pressure. How many do I need ...
  16. T

    Hydraulic high pressure piping project

    dear friend i am hydraulic high pressure piping project. but i not aware of calculations and formulas so can anyone tell me "how to select & buy a correct material grade for the high pressure pipe . i know the values 1. max pressure with stand = 25,000 PSI 2.Minimum Inner Dia :10-13 mm...
  17. S

    Can I get a 40KN force from a hydraulic cylinder powered by an electric motor?

    Im thinking of designing a tipping trailer for a car. I need a force of 40KN exerted to tip but would this be too much for driving with an electric motor powered by the car battery. If not what size of motor and pump would I need? thanks
  18. T

    Hydraulic piston break system problem

    Homework Statement The figure below shows the essential parts of a hydraulic brake system. The area of the piston in the master cylinder is 1.8 cm2, and that of the piston in the brake cylinder is 6.4 cm2. The coefficient of friction between shoe and wheel drum is 0.50. If the wheel has a...
  19. varun atri

    How can a hydraulic steering be replaces the modern power steering system

    Hi every one, i am a mechanical engineer working on a project hydraulic steering :smile:. i want to know that in power steering systems it has been used. but the thing is as far i know that the modern power steering system uses a hydraulic cylinder in addition to the rack and...
  20. S

    Thermal Insulation Of Hydraulic Cylinders

    Hi All, I'm working on a Hydraulic Tire Curing Press Project.There are Hydraulic cylinders in many regions of the press.Steam @ 220 deg c is used to heat the tire to bring about vulcanization process.The press earlier supplied to the customer had thermal insulation problems due to which the...
  21. R

    Hydraulic ram force calculation help?

    Hi, I was wondering how to calculate the force of a hydraulic ram in Newtons if the piston diametre is 20mm and the oil pressure is 52 bars. I would like it if someone could explain the formula as i can only find it with psi and imperial units on google. Also I have the shaft diametre of 4mm, I...
  22. D

    Two hydraulic press joined by a lever

    The two hydraulic press are joined by a lever, the ratio between the SA of the first press is 1:100 and of the second is 1:50, find If a force 10 Newton acts on the small piston of the first press a) the load b) mechanical advantage What is the load? Is it mass or force and which force And...
  23. D

    Calculating Pressure for a Hydraulic Car Lift

    A car service station uses a hydraulic car lift, the diameter of its pistons are 0.02 m and 0.32 m calculate the pressure required to raise a car of mass 1800 KG I don't know how to get the area ?
  24. F

    Pascal's principle hydraulic lift with torque involved

    Pascal's principle hydraulic lift with torque involved(need help with lever) Homework Statement A hydraulic jack is used to support a mass which has a mass of 30.7 kg. The mass is supported by piston 2 which has a mass of 0.250 kg and an area of 40.2 cm2 . A force is applied by the lever on...
  25. C

    Calculating force of hydraulic cylinder

    I want to calculate the force generated (as a result of expanding air) from pressure created by heating air up to a maximum temperature of 800 degrees Celsius. My flywheel with a radius of 0,030m is rotating at a speed of 850RPM and weights 0,27Kg. Angular velocity: w=850RPM*(2pi/60)=89rad/s...
  26. A

    Can I Connect a Hydraulic Pump to a 100hp Motor for 80 N*m on Each Wheel?

    hi i have a problem i have a motor 100hp and constant 2500rpm i need to connect to him hydraulic pump, that will rotate hydraulic motors connected to the wheels. i need to get about 80 N*m on each wheel how to solve this problem? what formulas i need? thank!
  27. A

    Calculating Hydraulic Motor Requirements for Plant-Pulling Device

    Hi, I would appreciate if someone can help me figure out this design problem. I am working on designing a device to pull plants from the soil. This device consisting of two steel solid core rubber coated rollers. The rollers will be positioned facing each other and rotates in a way to pull...
  28. T

    Is it possible to connect two hydraulic jacks?

    it is possible to connect two hydraulic jacks together? i want to lift an inclined board using two hydraulic jacks at both ends of the board. is there a way that i can connect two hydraulic jacks together so that when i pump one of the jacks, the other is also being pumped. Any ideas how to lift...
  29. P

    Can a Bleed Line Improve Air Removal in Hydraulic Circuits?

    Hey all, I never studied hydraulic circuits but I needed to design/make a hydraulic system for some research equipment. The system (in the attached schematic) has been hooked up and used for 6 months or so. However, I think we went the hard way on with getting the air out (we had no idea...
  30. O

    Hydraulic lift problem - hot hydraulic fluid

    I have hydraulic system that lift something heavier than 1 tonne. My problem is the hydraulic fluid always get so hot and sometimes because of the heat it could not lift its load (loss power). I tried to increase its flow rate and its worked for now. But it way above the permitted flow rate...
  31. F

    Electrostatic Discharge in Hydraulic Systems

    I know this is a general Mechanical Engineering forum, but there is no Hydraulic forum and this is the nearest trade. https://www.youtube.com/watch?v=47Dx6TvuJTc I've been doing a project on electrostatic discharge, and the company I work for (I won't mention the name as I'm not here...
  32. T

    What Are the Roles of Pilot Ratios and Relief Valves in Hydraulic Systems?

    I have a few questions and was hoping you would have a few answers. What's the purpose of pilot ratio in counterbalance valves? Is it vital, or necessary to include in a catalog description of counterbalance valves? What information should be included when designing a product code for...
  33. L

    : Hydraulic Press & Pascal's Law

    Is there any way to deduce pascal law from Newton's laws? Another question: in a hydraulic press, with the smaller piston with A=1, and the other with A=2, the force in both shouldn't be the same? When the smaller piston goes down a distance d, the other piston goes up a distance d/2...
  34. G

    Hydraulic Pump Closing a Floodgate

    Homework Statement -4" hydraulic cylinder/piston -closing a floodgate 4" in diameter, must exert force F=30,000lb to do so. -Piston stroke is 2'. -Hydraulic fluid specific gravity of 0.9. -Pump efficiency of 0.8 Find A) the pressure on the floodgate and B) the horsepower of the pump...
  35. A

    Air brake over hydraulic brakes

    Air brake over hydraulic brakes! Why air brakes are used in long vehicles like trains, instead of hydraulic brakes?
  36. J

    Automotive Could a 100% hydraulic system as a vehicle prime mover work?

    Given: I understand that there would have to be the equivalent energy source to drive the pump. That I will look to later (my gut says the real issue), but for the purposes of this discussion, assume endless power from a source of electricity or hydraulic pressure/flow, and you have to build a...
  37. K

    Produce schematic for a lathe hydraulic copying attachment

    Hi there! Im currently towards my 2nd year of my mechanical engineering course and on one of the assignments we have been asked to produce an electrical and hydraulic schematic for a hydraulic copying attachment for a lathe. Now unfortunatly we haven't really had much tuition with this part...
  38. K

    Any Tips for Coupling Neutronic and Thermalhydraulic Codes?

    Hi there, I'm going to couple WIMS & CITATION as neutronic codes with PARET as an thermalhydraulic code. Please let me know if there is any resources, papers or tips and tricks to do so. Thanks
  39. Y

    Understanding Hydraulic Resistance: A Comparison to Electrotechnics

    For better understanding of it's principles, electrotechnics is often compared to hydronics (and, probably, vice versa). But, why having the electrical resistance to a flow of charged particles - with it's basic unit "Ohm", there in general Physics is no unit of measurement of the hydronic...
  40. B

    Using a hydraulic press for sample testing experiment. Need Help.

    Hello, I am using a hydraulic shop press, to test the strength of acrylic weld joints. Here are my questions. -I replaced the pressure gauge that was included with a very precise digital gauge. The hydraulic piston that presses down has a removable circular head 2” DIA. Its neck is 1.48”...
  41. N

    Thermal hydraulic design of nuclear reactor core

    By a simple procedure , what should I do when I'm going through the thermal hydraulic design of nuclear reactor core...? .. I put initial guesses for the core dimensions ( fuel , clad , gap , length) initial guess for the fuel element pitch desired power ... I've found q'' critical heat flux...
  42. H

    API Specification for a Hydraulic Pressure Intensifier

    Greetings, We purchased a hydraulic pressure intensifier. It works by using piston areas.. so a high pressure piston and a low pressure piston causing reciprocation and thus intensification downstream based on the pistons ratio. (has internal check valves, a sequencing valve, and a pressure...
  43. R

    Dear Experts I like Hydraulic mechanisms as it can be used to lift

    Dear Experts I like Hydraulic mechanisms as it can be used to lift heavy things with little force. I like to find out more about it. 1. How is leaking prevented ? Fluid is used to transfer the energy. For example, oil. It is so fine, how can the oil not ooze from the piston-cylinder...
  44. W

    Optimizing Hydraulic Flow Rates and Motor Sizes for a DIY Stone Saw

    Im planning to build a stone saw with a 36 inch blade and plan to use a hydraulic pump and motor to power the saw blade The hydraulic pump will be driven by a 50 hp diesel motor Now the hard part i need to figure out flow rates pump and motor sizes and basic saw design i have been looking on...
  45. K

    CRANE: How to calculate the strengths on hydraulic cylinders? (static + dynamic)

    Hi there. I've got issues. Big ones. I need to simplify this crane structure, and calculate the strength on cilinder |c1c2| when applying a vertical load on the crane's hook. The purpose of this is to find how much of the strength is absorbed by the first cylinder (and possible the second one...
  46. J

    Calculating Leverage with Crates on Hydraulic Lifting Beam

    Homework Statement The crates( one create 500 kg) are placed on a hydraulic lifting beam: 1. State the order of lever used here 2. Calculate the effort required to lift the load 3. Calculate mechanical advantage for this system 4. Calculate the velocity ratio for this system. If the...
  47. Z

    Pascals principle and hydraulic lift

    says that the pressure is distributed evenly around a fluid. What I'm having a hard time understanding is the hydraulic lift, so I thought I would think of a simple system that could represent a fluid and then use that for intuition. Regrettably I did not get the same conclusions with that...
  48. H

    Hydraulic Problem: Fluid backing up into a closed tube

    Hello, I am investigating a phenomenon known as "Blood reflux" and I am interested in the Hydraulic Principles I need to understand to solve a problem related to this. Here is the problem: PROBLEM: - A 20 gauge plastic tube is inserted into a vein with a 6mm diameter. The end of this...
  49. R

    What are some resources for learning hydraulic design for a battle bot weapon?

    I am a freshman in college currently and I am looking for a comprehensive textbook that could teach my how to design a hydraulic system to operate in a robot. I'm on a battle bot team and we came up with a really ingenious idea for a weapon, but the only way for it to deliver the kinds of forces...
  50. Y

    Basic question about hydraulic pumps

    Hi everyone, I have been messing around studying Hydraulics on my own, but I can't get round something. The following things are things I concluded after reading books, sites, ... - The pump itself doesn't generate pressure, but when there is a resistance in the circuit, there is pressure...
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