# Questions tagged [hydraulics]

Questions about the flow and use of fluids.

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### Calculating the distribution of pressure amd velocity of a fluid in a pipe

Consider a container at a constant pressure P1. It is connected to another container that is under constant pressure P2 with a pipe that has a length of L and a crossection area S. A fluid flows ...
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1 vote
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### Hydraulic eng. problem

I need to solve this problem for a university course and I’m not sure how to. I’d really appreciate any help. The question is translated to English so I hope it still makes sense. I have a drawing to ...
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### Hydropneumatic issue

Could you help me by giving me examples of a task that was left to me. Design a hydropneumatic system for the actuation of transversal and longitudinal movement, applicable to a three-step precision ...
15 views

### What is the correct equation for McKibben force output calculation?

I found this post, but no matter how many times I try, either in radians or in degrees, the results are simply weird. My "correctest" result was -179533. The dimensions are 100mm of length, ...
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1 vote
41 views

### Flow control valve understanding

I am trying to get a more intuitive understanding of incompressible fluid flow in valves. I understand the basics of Bernoulli's priciple and the energy involved with incompressible flows through ...
1 vote
41 views

### What is the flow rate at pressure x when given these pressure drops?

I was given a work problem. There is a water pipe that has a leak. The leak appear very minor. Some staff decided to try and measure the leak after shutting the water off at both ends of the pipe. ...
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### Pessure required for pumping seawater through pipe with inlet at a depth below sea level

I need to calculate the head capacity required at the pump, to pump sea water from a depth of 100m below sea level i.e. inlet is at 100m below sea level, the recieving end is at 5m above sea level. ...
174 views

### Can an archemedes screw powered by a waterwheel supply water to a building?

This is an idea I had for a story I'm writing. It takes place in a building that has no power, but I'd like for some of its features to still work. One idea I had is a way to keep the water on without ...
54 views

### Best way to share and sell new CVT design?

What is the best way to sell an unpatented CVT design? It is hydraulic/direct drive design, and can function as a clutch mechanism. I am just one person, and not capable or inclined to build it ...
32 views

### Max. realistic velocity / flow rate through pipe, limited know variables

I'm trying to figure out a way to calculate the maximum (realistically*) possible velocity/flow rate through a pipe, when only following limited factors are known: viscosity of the fluid (water) pipe ...
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### Which electrical portable fluid pumping actuators that aren't based on electric motors, combustion engines, or piezoelectric actuators?

So, basically, I'm trying to find a practical, electrical, portable and efficient alternative for hydraulic pumps that doens't use electric motors, combustion engines or piezoelectric actuators. The ...
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1 vote
164 views

### How can I stop water flow in a hose after a certain water level?

I have a bucket that I want to fill with water only up to a certain level, the bucket is indoors, the first thing I thought of was a siphon like the one in a toilet but would prefer a smaller ...
55 views

### Computing the velocity of water under reverse flow conditions from storm water drain

I am trying to compute the approximate velocity of water during reverse flow from the outfall location to the street through storm inlets. This is generally seen during what is commonly referred to as ...
46 views

### Compression ferrules for bicycle hydraulic brakes

Between working on my and my girlfriend's bikes, I've come across different style compression ferrules (aka sleeves/olives) used in the hydraulic brake systems and would like to know: What is the ...
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### Estimate cycle of the pump per day

I have a pump system that is on for 5 days. For the entire 5 days, there are 3 days that the pump system is able to complete on and off cycle. I want to estimate the cycle of the pump (on/off) per day?...
37 views

### Estimating circular pipe flow velocity through a known elevation profile and known length with a known initial pressure and flow velocity

I have a known elevation profile spanning the length of my pipe (~600 meters). An elevation value is given for every five meters of pipe. At the beginning of the pipe, I have a known velocity (1.1 m/s)...
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95 views

### Hydraulic system single-action and double-action

I am looking at purchasing a hydraulic cylinder and a 12volt DC pump and motor to go with it. The pump and motor state that it is a single action pump, the cylinder mentions that it is double action, ...
71 views

### Solenoid Valve Resistance

This is basic but will a DC solenoid have 0 Ohms impedance when energized? For example, a valve in the closed position with 24VDC applied to the solenoid. Don't inductors have zero impedance for ...
1 vote
73 views

### What would prevent me from using this valve for water?

https://www.kingstonvalves.com/product/ksv25cr-stainless-steel-asme-soft-seat-safety-valve/ Looking to use this for water instead of air. I haven't seen a good reason not to as the physics of the ...
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1 vote
112 views

### How do centrifugal pumps connected in series increase head?

I've read that if you connect two identical centrifugal pumps one after another, the head of this system would be twice the head of a single pump. I have some difficulties understanding the processes ...
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1 vote
57 views

### Volume multiplying hydraulic pressure reduction unit?

I'm tying to figure out what something is called, assuming it exists at all. If I knew what to search for, I'm reasonably sure I could figure out which part would be suitable for the application, but ...
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### 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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233 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 ...
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### 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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41 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
320 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
247 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 ...
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1 vote
90 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 ...
49 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, ...
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### 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, ...
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423 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 ...
36 views

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

I clearly misunderstood something
786 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 ...
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1 vote
119 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 ...
41 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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### 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 ...
88 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 ...
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### 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
760 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 ...
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### 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 ...
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### 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 ?
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### 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 ...
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### 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 ...
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23 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 ...
77 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 ...
84 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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### 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 ...
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### 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