# Can someone explain to me how a 4-way valve works?



## joker (Sep 25, 2007)

I was wondering if someone wouldn't mind explaining to me how the 4-way valve works. I realize that a double acting cylinder will go in/out but was curious how a controller makes the valve work.

If i understand the 4-way correctly, it basically has 4 ports. An inlet, 2 outlets and an exhaust.









When triggered the valve sends air to one of the outlet ports that will result in the cylinder going in or out depending on port and it's relation to the cylinder.

Are one of the outlets normally open and the other normally closed? (i.e. Is air constantly going to one or the other?) If so will I be constantly losing air out the exhaust. Seems to me that there should be basically 3 signals from the controller - outlet1, outlet2, or off, but the controllers appear to be either on or off.

Thanks in advance.
Confused


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## Lotus (Nov 12, 2004)

joker said:


> I was wondering if someone wouldn't mind explaining to me how the 4-way valve works. I realize that a double acting cylinder will go in/out but was curious how a controller makes the valve work.
> 
> If i understand the 4-way correctly, it basically has 4 ports. An inlet, 2 outlets and an exhaust.
> 
> ...


Basically when power is on port A becomes open to send the air to the cylinder while port b sends the air to the exhaust port. When power goes off port b gets open to send the air to the cylinder and port a opens to send air to exhaust. Once the air is out of a going to the exhaust no more air will be being exhaust until triggered again. I hope this helps









Photo From Monster Guts


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## bradbaum (Jul 26, 2008)

The electrical part of the valve works the same as a relay, but instead of the electromagnet flipping a switch it flips the valve.

So either the you power the electromagnet (coil) or you don't and that flips the valve or doesn't.

I like the 4-way 5 port valves myself, in which there are two exhaust ports, one for each side of the valve. This tends to allow the cylinder to work faster due to less routing of the exhast air.


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## joker (Sep 25, 2007)

I'm just having trouble understanding how this setup doesn't constantly send air out the exhaust. Either way an exhaust is open right, so how does it not drain the air supply?


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## bourno (Jan 21, 2006)

Pressure is sent to one port at a time. The other side is opened to the exhaust to allow the piston to move properly. The pressure line is never connected to exhaust.


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## joker (Sep 25, 2007)

bourno said:


> Pressure is sent to one port at a time. The other side is opened to the exhaust to allow the piston to move properly. The pressure line is never connected to exhaust.


Oh ok so basically each movement of the valve will only exhaust the amount of air that it takes to fill the cylinder (volume of the cylinder).

Sorry for being slow. I like to know how things work especially if I'm going to be using them. I was about to just accept the fact that it works and move on.

Thanks again.


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## jabberwocky (Apr 30, 2008)

^^^^^^^^
Exactly....... the only "exhausted" air, is the are being moved "out" of the cylinder.
The other question about the valve being contantly on is "yes".
One side is always being feed air.
Goodluck.


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