10
votes
Why are train brakes so complicated?
This answer addresses the following sentence:
So I'd expect to see the brakes applied by a spring that is capable of stopping the wheels of a fully loaded car, and a single-acting cylinder that works ...
- 24.3k
10
votes
Why are train brakes so complicated?
You need to consider what happens if a hose bursts, and your spring-applied brake locks the wheels on one or more cars - how do you get that train back to the depot? There could be a manual brake ...
- 451
5
votes
Accepted
Are precision pneumatics possible?
While pneumatic systems can be controlled in a non-discrete manner as GisMofx mentioned, that is generally not the norm because the control system to achieve that movement is more expensive that ...
- 7,904
5
votes
Is it safe to use a 125PSI rated auxiliary air tank with a 150PSI air compressor?
Don't do it!!
Just buy a pressure regulator to put between the two tanks that will decrease the pressure to below 125. You can get these for \$17 at home depot (https://www.homedepot.com/p/Husky-1-4-...
- 2,646
4
votes
Calculating piston force for pneumatic vs hydraulic
The formula is valid independant of the fluid.
The force in an hydraulic system is based on pressure and area - a height difference between pistons is usually small compared to the acting pressure ...
- 15.4k
4
votes
What is the equivalent of a capacitor in pneumatics?
The equivalent of a capacitor in terms of pneumatics would be a chamber such as a metal sphere the size of a tennis ball. It would be necessary to have an external vacuum pump to evacuate the air ...
- 6,920
4
votes
Accepted
Force control of pneumatic piston
No, your 5/3 valve will give you on-off control only.
You need an electric pressure regulator also known as a "proportional valve". Typically these will take a 0 - 10 V or 4 - 20 mA control ...
- 10.3k
4
votes
Why are train brakes so complicated?
With an "spring apply / air release" system the spring pressure may not be enough to apply adequate braking force. Using compressed air to apply the brake allows much higher braking forces.
...
- 10.3k
3
votes
Accepted
Why were pneumatic thermostats commonly installed in buildings?
In the 1940's and 50's, dynamic system controllers were invented which used air pressure to work. It was possible in fact to design and build not only analog control mechanisms but also binary logic ...
- 14.3k
3
votes
Are precision pneumatics possible?
Yes, it's possible.
See here:
Position Control of a Pneumatic Actuator
and this youtube video here: Pneumatic Actuator With Position Control on YouTube
Many solutions use a servo controlled ...
- 1,578
3
votes
Accepted
Hydraulic Arm - Handbrake
It is a gas spring. They are rated in units of pounds and travel in inches. Typically ranges are 10 to 200 pounds, and 6 to 24 inches. Here is one example :
https://www.amazon.com/JR-Products-GSNI-...
- 446
3
votes
Accepted
How to connect a pneumatic cylinder to a door?
Based on the threads at the end of your sample cylinder, you would be seeking a female threaded rod end:
There are a multitude of variations of this product, almost always including the words "rod ...
- 6,920
3
votes
Accepted
What is the equivalent of a capacitor in pneumatics?
The device is called a "receiver" in pneumatics - this is basically the tank you see on any garage compressor, or much larger and more elaborate setups in industrial settings. Its function can be ...
- 146
3
votes
How do I limit the pressure of a tank to a fixed PSI?
I understand your setup as follows (in flow direction):
compressor with cutout set to 150 PSI
tank (T1) rated for compressor, with safety valve
(planned) pressure regulator (PR)
additional tank (T2), ...
- 4,772
3
votes
How do I limit the pressure of a tank to a fixed PSI?
In industrial settings, the correct piece of equipment is referred to as either a Pressure Relief Valve (PRV) or Pressure Safety Valve (PSV). These are spring-loaded valves with a few specific ...
- 605
3
votes
Accepted
Pneumatic valve clicks but doesn't actuate
The specification for that valve states:
Working Pressure: 0.15 ~ 0.8 Mpa
For those still using colonial units, that's a minimum pressure of 28 psi.
The reason it doesn't move is that it's a pilot ...
- 10.3k
3
votes
Accepted
Is a pneumatic cylinder in general a linear or rotary actuator?
A pneumatic cylinder is linear by definition
The form factor for a cylinder defines this. You can turn this linear motion to rotary via a crankshaft or rack & pinion, to give two examples.
You ...
- 6,534
3
votes
Accepted
Triangle symbol in pneumatic diagrams
It is a two stage actuator where the triangle represents a pilot. That means that there is a pressure assist. The direction of the arrow indicates the direction of flow.
- 3,597
3
votes
Why are train brakes so complicated?
Because the system has worked for a long time and railroads don't want to spend money on improving a technology is time tested. Most railroads run locomotives that is over 25-50 years old. (Most north ...
- 31
3
votes
Why aren't pneumatic/hydraulic artificial muscle actuated humanoid robots more common?
As cool as they seem, fluidic muscles like these are, unfortunately, not on track to be viable for mobile robotics for the foreseeable future. There are 3 primary issues:
Controls. It's somewhat easy ...
2
votes
Accepted
What's the difference between a vacuum regulator and pressure regulator?
The difference is the side on which pressure is regulated, and the reaction curve.
Typical pressure regulator takes arbitrary input pressure (from compressor) and provides specified (lower) pressure ...
- 6,125
2
votes
Accepted
Is it standard practice to use a pressure relief valve as a pressure regulator?
Sort of.
Certainly things like pressure cookers and turbochargers use blow off vales as a routine way to regulate pressure.
Generally this is to make sure that internal pressure doesn't exceed ...
- 15.2k
2
votes
Need to route air, like a solenoid does, but with many output directions
One tube with a long axial slot which tightly fits inside another which has holes spaced such that rotating the internal tube connects to each hole in turn.
One issue is when you need to get to hole ...
- 15.4k
2
votes
Need to route air, like a solenoid does, but with many output directions
I'm sure someone has invented such a thing, but you could do the same with a distribution header/pipe and multiple outlet solenoids. Your software would determine which solenoid were turned on or off....
- 6,534
2
votes
Accepted
What is the "quick bleeder valve" in this tool changer pneumatic schematic (and other questions)?
It's common for CNC equipment to use air pressure to manipulate tools and collets and mandrels and other "non-precision" mechanical components. In the case of tooling, the engagement sockets provide ...
- 6,920
2
votes
Regulating pressure down inside vessel as it increases
The only way to keep pressure constant as volume is reduced is by let out the same amount of liquid/gas as the volume contracts. That is exactly what a pressure reducing valve does. As long as it ...
- 6,534
2
votes
Accepted
Regulating pressure down inside vessel as it increases
Have a second separate balloon that expands as the first is compressed.
This will also keep the pressure constant as the volume is increased if that is part of your requirement.
- 15.4k
2
votes
Accepted
How does 3 "liars" in Strandbeests work?
Draw the schematic!
Figure 1. (a) The circuit. (b) Step 1. (c) Step 2.
The circuit relies on slight differences in timing of the various components due to differences in friction and tolerance to ...
- 10.3k
2
votes
Accepted
2
votes
Is it safe to use a 125PSI rated auxiliary air tank with a 150PSI air compressor?
A 10 or 25 psig overpressure of a tank is well into a potential failure for the tank. The 140 psig safety valve is used because that accounts for the true pressure capability of the tank plus the ...
- 478
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