Schrader Bellows valve

[bigcreek]

Is anyone familiar with these Schrader bellows pneumatic valves? I have one on the back of a Chicago sheet metal brake which runs two air cylinders for the top clamping. Well the valve has two parts on top with a led on the top of each one. One of those LED's recently illuminated. Does anyone familiar with these things know what that means? Im assuming its not good but I don't know if it means failure or dirty or just what? I can try to contact customer support but sometimes its easier to just throw something like this out there on these forums since there are so many knowledgeable folks.
To add to this story the brake is rated to bend 8' of 3/16" sheet metal but recently it will only bend 6' of 3/16" tops and if you put a full 8' in there the top clamping leaf will not hold it down. So I replaced that valve because the old one was blowing air non stop out of a port. I took it apart and plastic parts inside had deteriorated and broke in places allowing air to flow unrestricted at all times. So I bought a new valve, but that didn't fix the issue of the top leaf not having enough clamping power so now I am wondering if the cylinders need repacking/replaced. it is a 1994 model dries and krump brake. Thank you in advance.

 

[DeeKay]

Take a picture or post up the part number on the valve, Schrader-Bellows makes all kinds of stuff. From what you described it just sounds like a double solenoid DCV with LED indicators for what solenoid is energized.
If your cylinders are bypassing I think you would still be hearing air coming out of your exhaust port.

 

[bigcreek]

The Schrader Bellows valve number is L6653921153 120 volt 12watt unit with a max pressure of 140 although the dries and krump book calls for inlet pressure to be 85 pounds. Ill try to post up some pics.

 

[DeeKay]

Looks like Parker owns that product line now.
https://ph.parker.com/us/en/ParkerExternalConfigCmds?Key=1045a73852-0b99-48cf-893e-fdd27a404aaa
https://www.parker.com/literature/L...PDN1000-2_Products/PDN1000-2US_Valvair-II.pdf

Those LEDs are just indicators of which solenoid is energized.

It's also 4-way,3-position closed center in neutral so I guess your cylinders could actually be bypassing and you wouldn't hear anything.

Looks like Parker owns that product line now.
https://ph.parker.com/us/en/ParkerExternalConfigCmds?Key=1045a73852-0b99-48cf-893e-fdd27a404aaa
https://www.parker.com/literature/L...PDN1000-2_Products/PDN1000-2US_Valvair-II.pdf

Those LEDs are just indicators of which solenoid is energized.

It's also 4-way,3-position closed center in neutral so I guess your cylinders could actually be bypassing and you wouldn't hear anything.

If you can do it safely, Pull the air lines off of the rod ends of the air cylinders or at the valve and actuate the valve; see if you hear any air coming out of that rod end port, then reconnect what you pulled off and do the same with the other side and listen for air. If you have bad seals, you will be able to hear.

 

[matt_i]

You can try increasing the air pressure to get more force out of the air cylinders.

Mechanical friction and/or a bind condition is likely your issue past that.

Be careful, lots of tonnage needed to finger-brake bend 3/16" steel @ 8' long....

 

[bigcreek]

Here is a picture of the valve. I drew arrows where there are some adjustment screws. Im wondering if these need to be adjusted at all? The brake manufacturer Dreis and Krump quoted me $1400 for the valve but I found a distributor and got it from them for $540, same brand, same model. Im just wondering if Dreis and Krump makes any adjustments to the valve to get it where it is supposed to be? What would those adjusters do because the air pressure is set before it enters the valve.

 

[DeeKay]

The two on top are your over-rides, you can actuate the valve manually(without power).
The two on the bottom look like flow controls but I'll do some more digging to make sure, I know they had an option for pressure control on some of these valves too, but I think that would be on the manifold base, not the valve body.

I just took another look at that picture, I can't tell from that angle but are the ones on the bottom in-line with the mufflers and the two exhaust ports? If they are, those are just your flow controls; they let you set how fast your cylinders actuate.

 

[no704]

Check Automation direct.