# Questions tagged [hydraulics]

Questions about the flow and use of fluids.

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### 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 ...
76 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 ...
95 views

### Calculating Minimum Pipe Pressure Requirement for an Irrigation System

I am setting up an irrigation system for my ranch and I have a hard time calculating the minimum pipe pressure requirements to reduce cost. I need to know the maximum pressure the pipe has to cope ...
74 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....
28 views

### Adding electric control to industrial hydraulic disk brakes

I'm trying to electronically control the service brakes on some construction equipment, in addition to maintaining the normal brake pedal functionality. The disk brakes are controlled by the valve ...
184 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 ...
144 views

### How Can I do punching of 0.22mm in stainless steel sheet (Sheet thickness 0.5mm)

Wanted to press punching of 0.22mm dia (Bottom) and on (top) 0.6mm dia Please suggest how can I make such die?
85 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 ...
244k views

### How to calculate flow rate of water through a pipe?

If a water pipe is 15 mm diameter and the water pressure is 3 bar, assuming the pipe is open ended, is it possible to calculate the flow rate or water velocity in the pipe? Most of the calculations I ...
36 views

### HPU minimum oil temperature

Two different HPU systems in different locations with slightly different oils Chevron Ranco HD 68 and HDZ 68 have the same minimum oil temperature 55. Their flash points are are 455 and 414 F ...
42 views

### Calculating discharge from a reservoir as the head of water decreases

Due to the dry weather we've been experiencing in the UK I need to calculate the discharge rate from some reservoirs for work and how the dropping water level will result in a reduced head and so a ...
44 views

### What's the most efficient air compressor to reliably deliver up to 15 litres per second at 10 bar? [closed]

Suppose I wanted to continuously supply up to 15 litres of air per second, compressed to 10 bar - what would be the most efficient type of compressor, i.e. the type requiring the least energy input in ...
59 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 ...
42 views

### Component selection type for fluid-mechanical system

I am creating an enclosure and need to get a water supply through a plastic wall inside to the core device. I imagine this water line will be a flexible tube and will screw on or snap to an adapter on ...
40 views

### Help calculating discharge rate from a reservoir as the water level drops?

I could do with some help calculating the discharge rate from a reservoir and factoring in how that flow will decrease as the head of water decreases. The information I have is: Maximum height of ...
44 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 ...
370 views

### On a Diesel/hydraulic DMU train what exactly does the “go faster” lever control?

Let's say that you are driving a Diesel Multiple Unit† with either mechanical* (i.e. an actual gearbox with multiple ratios) or hydraulic (i.e. two or more torque converters) transmission. When you ...
48 views

### How does hydraulic pressure booster works?

This photo shows hydraulic booster used in HPHT Hydraulic Press. I could not understand its function. How does this pump boost the hydraulic pressure ? Thanks.
47 views

### How to compensate for losses in a hydraulic system?

I have an engine ( 72240 kW... ) , probably the biggest internal combustion engine in the world and this engine has no camshaft. Instead it has an hydraulic system which controls the combustion, the ...
26 views

### What is the side way force on a flat membrane place perpendicular to the flow of current on one side, and stagnant water on the other

So basically imagine a plate being placed parallel to the direction of flow of water with water flowing with a certain velocity on one side of the plate and on the other side it is almost stagnant. ...
31 views

### Working out location of a hydraulic jump

This is the question I am working on: And here is part of the working i don't understand: I don't understand the process of plotting the profile - the little crosses marked on the diagram, how do ...
62 views

### Hydrostatic transmission to directly translate movement

I have been thinking about small hydrostatic transmission to directly translate movement of stepper motor (NEMA 17-23 size, geared with 3:1 or 5:1 ratio). My design currently involves 2 identical ...
79 views

### Pumps' geometric similarity

Given two pumps that are similar : $H_1=70-1.41x10^{-3}Q_1^2$ $H_2=100-1.1x10^{-3}Q_2^2$ Find the geometric scale : $\frac{D1}{D2}= ?$ I am also given maximum efficiency = 1. I tried solving but I got ...
90 views

### Difference in flow measurements in an open channel

I'm undertaking a civil hydraulics question. It involves the flow of water in an open channel down a river at $5m^3/s$ until the flow is split in two by a weir acting as a sluice gate allowing flow ...
45 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
20 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 ...
59 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 ...
54 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 ...
58 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, ...
109 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 ...
75 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 ...
43 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 ...
95 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 ...
31 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 ...
38 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 ...
55 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 ...
177 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. ...
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 ...
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 ...
35 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 (...
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 ...
66 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 ...
52 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: ...
24 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 ...
4k views

### Why do hydroelectric plants use turbines instead of an efficient 'water wheel' configuration?

I have been thinking about hydroelectric plants and I have been wondering why they are built the way they are. As in understand it, a stream of water is sprayed at a turbine, located at the bottom of ...
92 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 ...
371 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 ...
1k views

### Reverse float shutoff valve

I have an application that is drawing fluid from a reservoir via a standard dip tube. This application has a special requirement that once the fluid is depleted from the reservoir, the pump pulling ...