Engineering Stack Exchange
Engineering Stack Exchange

Questions tagged [hydraulics]

Questions about the flow and use of fluids.

Hydraulics can be about using pressurized fluid to do work or about the large scale flow of fluid.

245 questions
29
votes
4 answers

Why do hydraulic systems use special fluid - what's wrong with water?

As a hydraulics layman thinking about hydraulic systems, it seems that the important factor is to have a liquid that doesn't compress much or at all. Doesn't water meet this requirement, and what other properties should the liquid have (if any) that…
jhabbott
  • 5,990
  • 8
  • 32
  • 63
15
votes
3 answers

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 have found appear to need 2 of these: diameter,…
Richard
  • 341
  • 1
  • 3
  • 6
10
votes
2 answers

Hydraulic siphon spillway entry and exit velocity magnitude and profiles

I am working on the hydraulic seawater flow though a siphon spillway. My task is to determine at a location in front of the spillway the flow velocity and profile when The flow enters the spillway The flow exits the spillway See attached a…
Ruudc
  • 101
  • 2
9
votes
3 answers

Motor for a hydraulic pump in a hydraulic system

I am a complete beginner to hydraulic systems, and I've wanted to learn more about this area. I'm designing a hydraulic system that involves using hydraulics to push/pull objects using pistons. I have looked at what the basic requirements are for a…
Tom
  • 317
  • 2
  • 7
9
votes
1 answer

Calculate force to lift piston from a given closing pressure

I am trying to calculate the force required to close the valve on an annular blow-out preventer. A rubber ring (called a packing unit) closes around the pipe when a force is applied from underneath, as shown here: The actual valve has the hydraulic…
Blue7
  • 191
  • 6
8
votes
3 answers

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 move the “go faster” lever to a higher notch, what…
keithb_b
  • 81
  • 3
8
votes
2 answers

Force required to crop/cut a mild steel bar

I have cropping/cutting wedges with a thickness of 4 mm cutting either side of a round mild steel bar (17.5 mm). Imagine two wedges being driven together with a round mild steel bar in the middle (similar to the design of bolt cutters) These wedges…
J Lancastle
  • 81
  • 1
  • 1
  • 2
8
votes
2 answers

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 a dam (Pelton Turbine.) This does not seem to…
Hoytman
  • 189
  • 1
  • 4
7
votes
1 answer

Which is more durable in sandy desert conditions: electric motors or hydraulic pistons?

If we have a tracking system placed in a tough desert environment with occasional sandstorms and temperatures that go as high as 50C, which actuator would be better: a hydraulic piston or an electric motor with a gearbox? My main concern is…
Mohamed Hassan Allam
  • 91
  • 4
6
votes
4 answers

How do I add a resistance to mechanical movement in both directions, apart from friction?

What options do I have for creating a resistance to a mechanical movement apart from simple friction? Assume I have a lever, which will result in either circular or linear motion. I want to be able to apply a resistance to this motion, so that the…
John
  • 163
  • 1
  • 6
5
votes
0 answers

Bedload discharge for canals of triangular cross-section

All the methods I know of for calculating bedload discharge are for canals of rectangular cross-section (constant depth of flow). The bedload is first computed for a unit of width (using the constant water depth) and then multiplied by the width.…
J. I.
  • 51
  • 1
5
votes
1 answer

Minimising permeation rate of hydraulic fluid through hydraulic hose

I am designing an experiment where the hydraulic hose is going to be subjected to relatively high internal pressure for prolonged period of time and it is absolutely imperative that the rate of permeation is minimised. I have found one great book…
user2820052
  • 223
  • 2
  • 4
5
votes
1 answer

Hydraulic power source

I'm looking for a power source that is able to deliver 12V at 15-30A (yes, amps). I was looking at high capacity batteries, but looking at the specs, they either say they have a lower discharge voltage than 12V, or they don't say anything at all.…
Tom
  • 317
  • 2
  • 7
5
votes
2 answers

Recoil of hydraulic lift/elevator

I noticed that when a group of people enter in an hydraulic lift/elevator often when the last person steps in the lift/elevator has a small but noticeable recoil: the lift goes down a few mm then it compensates. This creates a recoil. It seems…
Luca
  • 159
  • 2
4
votes
1 answer

Where exactly will a hydraulic jump occur?

I know that an hydraulic jump can occur only when the Froude number is higher than 1 (supercritical flow), and I am familiar with the Bélanger equation. However, I feel like I have a fundamental misunderstanding about hydraulic jumps: if a jump can…
user2554
  • 225
  • 2
  • 8
1
2 3
…
16 17