Questions tagged [hydraulics]

Questions about the flow and use of fluids.

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25 views

Boundary layer thickness decreases as fluid velocity increases, so why is the boundary layer thicker in the turbulent region for higher velocities?

I am modelling transitional fluid flow over a flat plate, and investigating the effects of free stream velocity on boundary layer thickness. From what we have been told, increasing free stream ...
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1answer
31 views

Why is the head loss in submerged pipe is 0

Looking at this question : Point C head loss is 0 according to the author Bottom right Can’t understand why , any good explanation for this claim ? Look at page 33 at the top
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1answer
16 views

Will decreasing a pump's flow rate decrease the NPSHR?

I have a small open hydraulic system and I simply need to circulate hot (85C) water from the bottom of a reservoir back into the top at ~4GPM. At its lowest point the system has only 3ft of static ...
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1answer
54 views

Running Hydraulic Pump with High Torque Motor

It's my understanding that hydraulics are merely a means of gear reduction to move a given object. So then I'm wondering why I can't find a formula or way to determine the following issue: I want to ...
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3answers
99 views

I cannot properly understand the “pressure” referred to in Bernoulli's Principle despite my efforts

I get that with Bernoulli's Principle an increase in area = a decrease in velocity = an increase in pressure. I also understand the concept of pressure being force per unit area. My difficulty is with ...
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2answers
77 views

How is high static water pressure avoided in municipal water systems?

Most cities get their water supply from local sources (springs, rivers, lakes) so the pressure in the system is never more than what is produced by the pumps. But some cities get their water from ...
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1answer
54 views

Low maintenance device to trade flow rate for lift height?

Is there a compact device which can trade flow rate for lift height without too many moving parts? My particular application is a 10 meter deep and 10 centimeter wide well with shallow water level, ...
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1answer
53 views

Hydraulic system dynamics modelling

I'm trying to mathematically model an actuation system and it comes down to relating the pressure across the pump and the actuator as shown in the picture. Assuming no friction in the pipes and the ...
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1answer
45 views

Circuit to provide position control for double action hydraulic actuator

I was wondering how to construct a hydraulic circuit to control a hydraulic double acting piston/actuator enabling the electronic control of the piston extension. I have found the following pneumatic ...
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2answers
40 views

Hydraulic energy recovery for high-pressure, low flow (non-steady state) conditions

What would be the best way to implement hydraulic energy recovery while de-pressurizing a pressurized volume of silicone oil initially at 1500 bar. Can a piston pump be concievably repurposed as a ...
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1answer
36 views

Running a hydraulic pump below minimum RPM

If I had a pressure compensated, hydraulic piston pump, how might the performance look in terms of pressure if I were only looking in the regime of 0 RPM and the minimum ratedRPM? I.E If a pump was ...
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1answer
31 views

What voltage are these hydraulic valves and how to I control them?

I am building a new control system for an injection moulding machine, the last part I am trying to work out is the main pump. It has two proportional valves on the output, one labelled throttle valve ...
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37 views

Volumetric oil pump efficiency goes up when viscosity goes down?? Strange behaviour

Riddle me this : we are driving an external gear pump (this kind) at a fixed RPM. At start, when the oil temperature is low (and viscosity high), the volumetric flow is much less than when the oil ...
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1answer
48 views

Why would these hydraulic cylinders have 3 large connections?

I am trying to work out how a recently acquired Arburg 220-90-350 from 1982 works so that I can build a new control system and get it working. It's a direct clamping machine with no toggle. The ...
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32 views

How to get this hydraulic system working and help identifying parts and their function

I have recently acquired a 1982 Arburg 220-90-350 injection moulding machine, mainly just as a hobby to further my knowledge on injection moulding machines and control systems as I plan to modernise ...
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1answer
34 views

Brake selection problem

I have a quick question guys. I am gonna select a brake but I am not sure. A Crane Hoist motor has a rating of 300 HP and maximum speed of 1800 rpm. This motor is attached to a gearbox with a perfect (...
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1answer
29 views

Effect of flow through a static hydraulic pump on its RPM

What happens when fluid flows through a static hydraulic pump? Will there be a negative RPM to impede the flow? By static pump, I mean a pump with initial RPM = 0.0 and is not driven by external ...
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1answer
129 views

Head loss for T junction diverging water pipes

I am writing to ask for help with a T-junction pipe problem. Attached picture shows the pipe configuration. The schematic shows a large pipe with ID 16.5mm and smaller 4mm ID tubes connected to it. ...
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1answer
27 views

Hydraulic lift connected to two pistons

I just finished a problem, and got the correct answer, however I am confused on one of the mathematical operations that must be performed in order to get the correct answer. The problem is as reads: ...
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2answers
50 views

Stop Spa-to-Pool Siphoning Thru Spa Pump

I have a partially above ground Spa and an in-ground pool. When the spa is filled to spillover with pumps off, water siphons through the spa pump and into the pool until the spa water level drops ...
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1answer
20 views

Does a single-wheel brake intervention from ESC cause one wheel to be not brakeable by the driver?

Source: https://www.kfz-tech.de/Engl/Buchprojekte/HBremse/ESP3.htm Firstly, I don't know if this is the right StackExchange, but I will try nevertheless. Above I posted a picture of the hydraulic ...
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1answer
77 views

What specific technical concerns exist for China's Three Gorges damn on the Yangtze river?

Recently, many people (specifically geopolitical and financial analysts) have pointed out that there is a serious concern about China's Three Gorges Dam breaking and causing catastrophic flooding that ...
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3answers
90 views

Replicate stepper motor with gasoline engine

For those unaware of what a DC stepper motor is, it boils down to an electronic motor where the rotation can be precisely controlled, i.e. you can control the rotation of the motor in fractions of a ...
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1answer
248 views

hydraulic Motor/pump minimum speed

I have seen in many data sheets of Hydraulic Gear motor a spec called : "Minimum Speed = 450 RPM" ( 450 is an example) here is a capture from the linked datasheet below : In your experience ...
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1answer
119 views

How would you go about calculating the force required for an actuator to lift a bridge?

I have been trying to come up with the optimal way to calculate the force required for an actuator to be able to lift a bridge 90 degrees. (A drawbridge) The actuator is placed as follows: (The bridge ...
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0answers
15 views

Fitting a gaussian shaped nozzle into check valve piston?

So, for my downhole hydraulic internal cutter tool, I have the following parts: Top sub, body, piston, nozzle, O-rings, knife pins, knives and a bottom sub. I am trying to use a gaussian shaped ...
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0answers
32 views

How do I calculate Pressure drop across relief valve and then force on piston?

So, I'm designing a basic downhole hydraulic tool cutter of an OD = 5 1/2 in., and my tool contains a relief valve and a piston. I am trying to calculate pressure drop across the relief valve so that ...
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0answers
35 views

What domestic water valve is least likely to jam over time?

I'm doing some work on a domestic water system, mostly 15 or 22mm copper pipe with compression fittings. The work includes replacing various stop-cocks and drain valves some of which are probably 30 ...
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0answers
79 views

How many kWh this turbine would generate?

My grandfather and I are running some experiments down the river, however we don't have expertise in engineering so I bring up this question to the community and hope someone could help. How many kWh ...
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0answers
49 views

Reference book for hydraulic systems design

I'm looking for a good reference book on the topic of fluid dynamics/hydraulics systems engineering. I'd like a reference for simlpe/estimate calculations on things like major losses (pipes), minor ...
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23 views

Water distribution through N x Needle orifices

Consider a water distribution setup consisting of a feeder line blocked at one end but having 100 needle outlets all the same size. The feeder line cross sectional area is much greater than a needle ...
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1answer
25 views

Bi-directional liquid transfer

I'm attempting to design a system that consists of 4 secondary(ABCW), 1 primary(Film) tank, and a pump. The idea being to Transfer the contents of each secondary tank to the primary one, then back to ...
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1answer
103 views

Hydraulic Brakes - Why motorcycle brakes more powerful than bicycle brakes?

I was wondering why motorcycle brakes have so much more stopping power than bicycle hydraulic brakes (Than can be found on mountain bikes for example). The rotor has a bigger size which gives better ...
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1answer
48 views

Distribution of water through a pipe network

I have a network of stainless steel pipes that are distributing water throughout a building. I know the flow rate of water entering the system is 600 IGPM, but am unsure of how this water will be ...
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950 views

How to calculate the flow rate of a gas through a pipe?

I am trying to calculate the flow rate of Nitrogen through a cylindrical pipe. I only need a ballpark value, and the only information I have is the inlet pressure as 15 psig (assuming the same ...
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2answers
76 views

The Cavitation Problem

I'm new here and would like to ask where the cavitation would happen in my design. Thanks
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1answer
250 views

Determining steady flow between two reservoirs with two different pipes in between

Two reservoirs are connected by two pipes with different diameters in series. The elevation of Reservoir A is 40m and Reservoir B is 35m to respective water surfaces. The first pipe is 500 m long with ...
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1answer
41 views

How do I Calculate Pressure at Multiple Points in Time while Filling a Container with Water?

Say I have a container completely full of water with a volume of 3000 gallons and I'm filling this container with water at a rate of 8.2 gallons per minute, it's already full at 200 PSI, how do I ...
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0answers
66 views

Head loss from rectangular slot orifice flowing up?

For sizing purposes I'm trying to calculate head loss for a level spreader outlet for water, where the water is being supplied from below by pressure. It's essentially a reverse slot drain—instead of ...
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1answer
53 views

Deriving the ideal equation for sluice gate problems - incompressible inviscid fluid

I'm trying to figure this problem out, i know the correct answer, and i know the method, but for some reason i'm missing something and i'm just not getting there, any help would be greatly appreciated....
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6answers
3k views

Does a motor suffer damage when resistance to the intended motion is met?

I'd like to create something similar to a hydraulic press. I know I need some sort of motor, but I was curious about a fundamental question about motors when used in a system where the force required ...
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2answers
120 views

Hydraulic linear actuators as CNC axis instead of screws

Lately I've been watching some videos on machining and hydraulics as it always interested me. I was toying with the idea of building a budget CNC mill with threaded rod for the axes, but the issue of ...
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1answer
77 views

Constant force opposing hydraulic winch

I have a situation that I am hoping to solve with the use of electric motors, and a variety of controls. I have a hydraulic winch which turns at speeds from 0-60 RPM. This winch is coiling and ...
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1answer
42 views

Low-Flow Nozzles for Corrosion Spray Testing

So, for a cyclic corrosion test system, I need a nozzle or arrangement of nozzles that provides a flow rate of 45ml-140ml of salt solution per hour to an area 60cm square. All commercial nozzles I've ...
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0answers
52 views

Static load analysis for four-bar linkage?

I am facing a difficult question and can't find answers anywhere else. What on the left is a hydraulic ram, it's pushing the box in the centre to move upward, while the four-bar linkage attached on ...
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1answer
1k views

Mechanism of a manual Crank Adjustable Height Standing Desk

I am trying to figure out the lifting mechanism of a manual Crank Adjustable Height Standing Desk. Please see the image below: My question is what it is inside the metal frame (check the red marked ...
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2answers
562 views

What is the difference between hydraulic and ABS brakes?

Recently I read an article about ABS brakes. In that, they repeated several times the term that traditional hydraulic brake replaced with ABS brakes. Why it so? The reason for choosing ABS is ...
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1answer
68 views

Help with simple hydraulic circuit to use for a four legged Robot

Firstly i am new to hydraulics, i want to build a hydraulic circuit that powers 4 cylinders at each leg of a Quad-Wheeled-Robot. The idea is to move the Chassis of the Robot up and down in all ...
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1answer
37 views

Can hydraulics be used with a squarish piston?

I'm designing a custom part that needs an active shock absorber and space is restricted. I most likely won't be able to use a stock absorber and was thinking, can two squarish tubes be made tight ...
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1answer
79 views

How are the modern hydraulic cylinders very precisely controlled?

My guess is that they use brushless Motors that in turn powers the hydraulic pump. But there must be some kind of valve that could help in the process. Still the burning question is just by adjusting ...