# Questions tagged [hydraulics]

Questions about the flow and use of fluids.

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### 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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### 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) ...
29 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(...
17 views

### Can a hydraulic vane motor have a specific rotational output?

If a vane motor/pump was used in a hydraulic circuit, could the rotation of the vane pump be controlled for slight movement in angles? I imagine this would would require a feedback controller, with ...
1 vote
13 views

### Is capillary pressure significant?

I have a hydraulic system pressure to be measured in cm of water. It is done by tapping a graded tube, and simply measuring the height of the water column (usually at around 10-20 cm of water). If I ...
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1 vote
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### Is there a mechanism that allows this kind of piston/plunger movement?

I am trying to create a prototype for a gravity energy storage system, and I need to release potential energy stored in a heavy load of mass M, raised to a height *H. I intend to use the mass ...
92 views

### Why are hydraulic systems widely used to multiply force ? won't a couple of gears do the job?

Hydraulic systems seem to have become ubiquitous. From huge cranes and excavators to disk brakes to door hinges. Basic requirement everywhere is the need to multiply force; trading greater force for ...
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### Can an AC compressor used as a Hydraulic pump?

Can a car ac compressor be used as a Hydraulic pump ? Does it require some modifications to do so or is it impossible to begin with and the compressor can't handle the oil?
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1 vote
591 views

### How to lift an antenna tower into position?

I am considering getting a 100-ft antenna tower for mounting a weather station. However, the problem is how to erect it. It needs to be easily to lower in case I need to service the weather station. I ...
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### Mathematical model of an hydraulic jack

How to find a mathematical model of this hydraulic jack system? I'm confused about the part when the piston extender, check valve 1 opens and check valve 2 closes, then liquid from the bottom tank ...
94 views

### Q: Could you siphon an 10 meter tall water column?

This question might be better suited for this stack. In the physics stack, I posted about a question about siphoning. https://physics.stackexchange.com/q/677102/259268 An 10 meter tall cylinder is ...
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### Is a Tesla Valve a good fit for this requirement (prevent heavy load accidentally crashing downard but less restriction otherwise)

I want to design a hydraulic platform that allows/ensures: The GRADUAL DESCENT of a heavy load (e.g. a FULL shipping cargo container) from a height H1 to height H2 (where H1 > H2) - without the ...
22 views

### Everyday examples of hydraulic pressure drop generating heat

I'm interested in hands-on examples of voltage drop in electronics dissipating the energy as heat, and, thought that the hydraulics analogy, that is the same thing, might be a good way to intuitively ...
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### multiple sequencing circuit for sequence A+B+B-C+C-A- by Cascade method

I am learning pneumatic circuit and i came across this problem of Designing and draw the multiple sequencing circuit for sequence A+B+B-C+C-A- by Cascade method for the Pneumatic system. the sequence ...
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1 vote
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### Why actuators are mounted in inverted position?

Hope you are doing good. Can anyone please explain to me why actuators are mounted in inverted position on some excavators? Please see the image for better understanding of my question. Another ...
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1 vote
81 views

### Resistive divider hydraulics analogy, is this true?

The formulas for hydraulics and electricity are generally the same (theoretically), or for any type of flow. Air, water, hydraulic fluid, electrons... As shown on this website, a "hydraulic ...
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### 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 ...
1 vote
111 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 ...
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### 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 ...
1 vote
47 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 ...
42 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 ...
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### 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.
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### 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 ...
56 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 ...
69 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 ...
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1 vote
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### 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. ...
94 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 ...
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### 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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1 vote
71 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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1 vote
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### 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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1 vote
213 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 ...
1 vote
154 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 ...
116 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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### 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 ...
1 vote
67 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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### 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 ...
1 vote
191 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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1 vote
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### 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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### 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 ...
55 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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### 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 ...
92 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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### 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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### 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 (...
1 vote
32 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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### 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. ...
111 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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### 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 ...
1 vote