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# Questions tagged [hydraulics]

Questions about the flow and use of fluids.

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19 views

### Effect of pump suction lift on pump vibrations and motor current

Consider the case of an electric motor driving a centrifugal pump. The pump is installed above the tank. In Case-I, the tank is completely filled with water. In Case-II, the tank is emptied and thus ...
277 views

### What are the Units of flow coefficient Cv? And relationship between flow coefficient Cv formulas of incompressible and compressible fluids

I tried to understand flow coefficent Cv of a valve. There are many similar discussions on the Internet, e.g., https://www.pneumatictips.com/what-is-the-flow-coefficient-cv/ There are two formulas for ...
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35 views

### Would connecting a small hydraulic pump to a larger hydraulic motor result in force multiplication?

In a hydrostatic transmission system, hydraulic pumps drive hydraulic motors (basically a reverse pump). If you were use a smaller hydraulic pump as an input and a bigger hydraulic motor as the ...
• 25
36 views

### Are there hydraulic torque converters that are specifically built to work like reduction gearboxes?

As far as I understood from this video, there are torque converters and fluid couplers (a hydraulic clutch), but certain types of torque converters kind of work by performing the two functions at ...
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1 vote
27 views

### Why did pressure decrease above the piston?

I can understand the pressure increase below,but why did pressure decrease above as more bricks were added? Image source: https://www.youtube.com/watch?v=4REdJIW6-Kg
39 views

### How does the hydraulic valve system work in excavators?

There are many types of valves used in excavators. Two are important: the main valve and the pilot valve. Is the pilot valve is controlled by the operator and the main valve is controlled by the pilot ...
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1 vote
80 views

### How many pistons are used in Excavator Engine and how they coupled with pumps?

As I am examining the components of a Caterpillar 323D hydraulic excavator, I would like to inquire about the specifics of its diesel engine. Can you provide information on the number of pistons and ...
• 11
20 views

### Design a manifold block and calculation of pressure drop

How to calculate pressure drop inside a manifold block with different pipe sizes for one connection to another. Overall the manifold block maximum working pressure is 10 bar. Can anyone send me basic ...
1 vote
86 views

### Pumped storage hydropower, how to power the pumps?

Regarding pumped storage hydropower, In the case of some high altitude upper reservoir that feeds several turbines located at the bottom of a valley, where there's a lower reservoir too. Assuming in ...
• 248
43 views

### Is there a way of find the ideal balance between pressure and fluid flow in a hydraulic system?

So, I have 72 hydraulic McKibben actuators with 30cm in length and 14cm in width under 400 kPa (or 4 bar) that lifts a 5 ton weight that I want to actuate in a third of a second (continuously, ...
• 25
12 views

### Recommended books for calculations in hydraulic and pneumatic systems

I'm starting to learn about hydraulic and pneumatic systems. Although I have some idea of the basics, I would to dive deeper into the field. Are there any books on hydraulic or pneumatic systems, ...
• 101
40 views

### Can a compressor give the same discharge pressure even if suction pressure varies?

The task is to maintain compressor discharge pressure at 200 bars. The inlet pressure varies with time from 200 bars to 10 bars (emptying a compressed air tank and compressing to transfer it to ...
• 11
32 views

### Why would the compressor provide more pressure than necessary? Isn't the pressure determined by the resistance?

I clearly misunderstood something
69 views

### How to build a hydraulic standing desk?

I am trying to build a standing desk but I want it to be wireless (aka - no electricity needed). My idea is: have 4 hydraulic pistons that extend (from 60 cm (25in) to 120 cm (50in)). They will be ...
• 101
1 vote
71 views

### How to transfer high pressure hydrogen using flexible pipes?

The task is to transfer hydrogen (high pressure gas > 400 bars) from offshore platform to land. To do so we have to use flexible pipes but for high pressure and high flow rate I'm afraid we can't ...
• 11
30 views

### Do 6/3 proportional valves like this exist?

Like a directional valve but used to select either pair of supply and return. Could be done with two regular 5/3 valves, but it would be nice to use only a single valve. Does something like it exist?
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28 views

### Input power unit for Heavy Duty spool hose

I'm trying to design a machine for spooling a hose at a mining application. Considering all hose length, mass, spooling diameter and pump the peak torque would be of To = 10267 Nm. It sounds a lot but ...
31 views

### Hydraulics sluice gates and hydraulic jumps

I was wondering if anyone has an understanding on hydraulic jumps and sluice gates? Why can you only use the energy equation for before and after the sluice gate? Why not at two points after the ...
• 1
20 views

### How does high inlet head affect outlet head on a fixed speed centrifugal water pump

I am curious to know what happens to a fix speed centrifugal water pump's outlet head if the inlet head is already relatively high. For example, say a pump is said to have a max head of 10m. If it is ...
99 views

### How to calculate the dimensions of a McKibben actuator based on the force you want it to apply?

I intend on design and build a McKibben hydraulic muscle that can lift 5 tons by itself, it won't be attached to a human or anything like that. I tried to search for methods to calculate the amount of ...
• 25
49 views

### Any scientific research papers on electromagnetic active valves using variable viscosity electromagnetic fluids?

I know the title is quite a mouthful, but let me explain (also, I couldn't find anything on the subject, maybe because I'm using the wrong words). I saw some time ago a video about a variable ...
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1 vote
84 views

### Do excavators use electronic joystick and solenoid valves for direction control?

I studying how flow control happens in excavators. I came to know that the low pressure pilot line is used to control the high pressure hydraulic flow control valve (pilot operated direction control ...
• 443
50 views

### Confusing terminology for "normally closed/open" - It means the opposite in electronics (relays) versus fluids (valves)

I'm an electrician and "normally open" / "normally closed" is well known to me. I recently started to also work on heating systems including the pneumatic system that controls some ...
• 109
21 views

### How to divide the water flow into pipes with equal flow each from a free surface?

From a free surface pond, I'd like to divide the outflow into two separate pipes and direct them in two different places. Each outflow has to be equal. Do you have an idea ?
• 101
44 views

### How to calculate time it takes for a cylinder to extend, if the pressure is not constant and the pump flow rate varies by pressure?

I am analyzing a hydraulic system that extends a single-acting cylinder. Due to a mechanical linkage, the force that the cylinder needs to exert decreases as it extends (and subsequently the pressure ...
• 31
94 views

### Why excavators use Hydraulic motors for rolling or moving forward instead of diesel engine?

I am currently studying How excavators work? and came to know that "In excavators diesel engine is used to drive the hydraulic pump. The high pressure fluid from hydraulic pump is used to run the ...
• 443
21 views

### What kind of system should I use to move the toroids of my CVT transmission?

I have a CVT transmission, which consists of a metal belt and four circular toroid discs, that form two pulleys. I need to be able to move the two toroids further and closer together. This movement ...
42 views

### Are there hydraulic cylinders that provide thrust and at the same time transmit rotary motion from a motor to a generator?

I am searching for a practical factory-made hydraulic cylinder (actuator) that can provide an axial push of 140 kN against the shaft of the rotor of an electric generator and also transmit the 90 kNm ...
78 views

### Are two forces required to cause shearing?

If we have a fluid, is one force acting along the surface of it enough to cause sheering? In most diagrams I see for real Newtonian fluids they show two forces of equal magnitude along the top and ...
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58 views

### Understanding continuity equation

The volume for an open tank is given: <$V = L \cdot L \cdot h(t)+ h(t)^2 \cdot tan(\theta)$> Where h is the volume of the liquid within the tank. I want to calculate the change in height as a ...
• 1
36 views

### Is NJDOT's method of calculating friction losses correct?

I have been attempting to develop a spreadsheet to calculate the hydraulic grade line (HGL) of a pipe system generally using the criteria set forth by the New Jersey DOT (NJDOT). Their Roadway Design ...
1 vote
46 views

### Are there hydraulically actuated pneumatic valves?

I am working on a hydraulic system that is powered by an air-hydraulic piston pump, the pump uses pneumatic pressure to drive a piston which then pressurizes the hydraulic system. The system needs to ...
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20 views

### Any liNear software users? I need help with potable water calculation

I was doing calculation for potable water system network from Revit in liNear software for MEP, and the only error I get is "Pipes are located in another trade. Review the situations and resolve ...
17 views

### How to determine of pumps required on a pipeline

I have a 14km long pipe with total head loss of 113m, transporting water at 40m3/h. How do I decide how many pumps I need? I understand headloss is 113m, but I still don't get how does this tells me ...
33 views

### Correct Hydraulic Symbol for Check Valve

I was looking in a few different hydraulic power textbooks for symbol information and I noticed that on of them referenced a check valve with this symbol: Is this "full" block symbol ever ...
44 views

### PC based real time control system

I am newbie, and I want to update an existing control system, which works with a 486 PC with AD/DA card currently. Is it a good idea to find a solution with a windows 10 PC, and a USB AD/DA card? The ...
1 vote
137 views

### How does this transmission valve "hydraulic computer" work?

I just came across this: The claim is that it is a kind of analogue computer. But I don't see any moving parts. How does it work? EDIT: If someone could draw lines on the diagram to illustrate, that ...
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22 views

### Hydraulic Hole Punch

I have been designing a hydraulic hole punch circuit looking at what was previously done I came across this symbol I have never seen before and have mixed feelings on what it is doing. I have been ...
61 views

### Incompressible Fluid Flow in horizontal pipe segment which encounters tilted pipe segment - Continuity Equation

Say that we have water flowing horizontally in a pipe of constant diameter. The continuity equation for incompressible fluids, which is a statement of mass conservation, guarantees that the flow rate ...
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42 views

### will a hydraulic gear pump be capable of the same pressure at all speeds?

I'm trying to build a hydraulic power unit with a 5 horsepower electric motor, gear pump and tank. The flow requirement for the system is 1.7 gallons per minute. The pressure requirement is 3000 psi. ...
• 101
1 vote
24 views

### Hydraulic circuit part question [Blanking Cartridge]

There is a part in this circuit called a "Blanking Cartridge". Its symbol looks identical to a standard capacitor in electrics. I have no idea what this part does. It is connected in ...
111 views

### Calculate hydraulic cylinder and pump forces on backhoe

I have a field find mini backhoe from a shut down manufacturer. The product is a beaver Pro QT50 backhoe used for small tractors, atvs, and pick up trucks. Unfortunately, there's no documentation on ...
• 101
19 views

### Pressure transducer connection leakage

I need to study the circuit diagram more, on this 24 V system, but with regards to hydraulic pressure transducers on each end of squeeze rams, on four banks/pairs of rams. If a pressure transducer has ...
1 vote
29 views

### Understanding flow curves of an hydraulic directional proportional valve

In the picture below you can see the command signal to flow curves for a proportional valve I'm using. Since I'm using it to control the speed of a cylinder I was looking at the looped flow path ...
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17 views

### Stability analysis of pressure relief valve using jacobian matrix

I'm modeling a pressure relief valve in order to find the limits of stability using the Jacobian matrix at an equilibrium point. The equations are the folowing:  \ddot{y} = \frac{1}{m}(A\cdot p\...
31 views

### Risk of operating hydraulic gear pumps below minimum speed

I'm looking at Marzocchi micro gear pumps, particularly the 2.00 model. Speed range is 800-200 rpm (although page 20 shows flow for 100-3500), but in my application I plan on using a bi-directional ...
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77 views

### How to Calculate Pressure at a Elevated Tank's Tap

If I had two tanks of equal diameter, and one was was shorter but elevated, but the other was taller but sitting on the ground, which tap (with both taps connected to the bottom of the two tanks) ...
63 views

### Can a design where syringes draw and push water to manipulate buoyancy be classified as a buoyancy engine?

Beginner question here: So my partner and I are trying to design a buoyancy engine where a motor operates a ball screw that draws and pushes syringes in order to draw and push water in the syringes(...
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