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 ...
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  • 22.7k
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 ...
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  • 401
5 votes
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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 ...
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  • 7,489
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-...
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  • 2,511
4 votes
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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 ...
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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 ...
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  • 14.1k
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 ...
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  • 6,292
4 votes
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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 ...
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  • 8,449
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. ...
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  • 8,449
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 ...
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  • 1,578
3 votes
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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-...
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3 votes
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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 ...
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  • 6,292
3 votes
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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 ...
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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), ...
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  • 4,643
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 ...
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3 votes
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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 ...
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  • 8,449
3 votes
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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 ...
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  • 4,810
3 votes
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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.
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  • 3,425
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 ...
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  • 31
2 votes
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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 ...
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  • 6,133
2 votes
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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 ...
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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....
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  • 4,810
2 votes
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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 ...
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  • 6,292
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 ...
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  • 14.1k
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 ...
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  • 4,810
2 votes
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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.
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2 votes
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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 ...
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  • 8,449
2 votes
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What is this pneumatic connector called?

I searched for "Schraeder Hose Barb". !
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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 ...
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  • 466
2 votes

How do I connect multiple water-filled syringes?

If the pressure is not too high you can use something like the Luer system there are plenty of options for connectors and valves etc.. I have found parts up to 1050 PSI. But most stuff can't handle ...
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