1/4 Air Horn Solenoid Valve problem

[jmamrak]

I have a brass 1/4 solenoid valve. It seems over time it has slowed in its closing of the valve. It used to stutter very well but now it’s ramping down and has a different sound. It is more or less fading out instead of turning off quickly. Has anyone experienced this before? Is there a way to clean the valve or should I just replace it?

Thanks

 

[Sparky_911]

Try cleaning it out. May be corroded due to moisture over time in the line. If so, replace. If not, a few drops of air tool oil might square it up.

 

[bpollard]

Sparky911 is most probably right, but i would strongly advise replacing it. Better to replace it with a new one than get stuck in the middle of a response with an air horn that won't stop and is stealing away all of your air supply.

just my .02
Bob

 

[shues]

Sparky911 is most probably right, but i would strongly advise replacing it. Better to replace it with a new one than get stuck in the middle of a response with an air horn that won't stop and is stealing away all of your air supply.

just my .02
Bob

Replacing the solenoid is likely a wise idea. But in the meantime don't forget, modern air brake systems have a mechanical low pressure cutoff device known as an pressure protection valve. The auxiliary air system should stop receiving air if the system pressure falls below the pressure at which the pressure protection valve is designed to cut off, leaving sufficient air pressure to keep the spring brake disengaged and to allow normal use of the service brake.

 

[bpollard]

Replacing the solenoid is likely a wise idea. But in the meantime don't forget, modern air brake systems have a mechanical low pressure cutoff device known as an pressure protection valve. The auxiliary air system should stop receiving air if the system pressure falls below the pressure at which the pressure protection valve is designed to cut off, leaving sufficient air pressure to keep the spring brake disengaged and to allow normal use of the service brake.

i didn't kow that! thanks for the info

Bob

 

[Nolines]

Even I didn't know about the additional safety valve but then it has been a long time since I drove something with air brakes, usually if the pressure got too low the emergency brake would turn on.

 

[jmamrak]

Try cleaning it out. May be corroded due to moisture over time in the line. If so, replace. If not, a few drops of air tool oil might square it up.

Thanks for all the responses!
I did replace the valve and i bought a higher quality one. That did fix the issue. I am curious how to clean the old valve? I did take that nut off the solenoid but I didn’t see how the valve came apart... they looked to be two separate assemblies. Any thoughts?

 

[Sparky_911]

IF they hey are threaded together you should be able to separate. Will likely have to clamp the body in a vice and put some muscle behind it. That's a big if by the way.

If the noid and valve body are pressed together then all you can do is blow it out with air gun. You might be able to get a pipe cleaner or bore brush in there. Activate the solenoid with 12v and it might open enough to scrub/blow out. Squirt a few drops of tool oil (3in1 or gun oil works too) and cycle on the bench several times. Put it under air pressure and see if that solved the problem.

Or just toss it, lol. Less PITA. Ha ha.

 

[jmamrak]

IF they hey are threaded together you should be able to separate. Will likely have to clamp the body in a vice and put some muscle behind it. That's a big if by the way.

If the noid and valve body are pressed together then all you can do is blow it out with air gun. You might be able to get a pipe cleaner or bore brush in there. Activate the solenoid with 12v and it might open enough to scrub/blow out. Squirt a few drops of tool oil (3in1 or gun oil works too) and cycle on the bench several times. Put it under air pressure and see if that solved the problem.

Or just toss it, lol. Less PITA. Ha ha.

I did take it apart and clean it. I took a picture to show how it comes apart should anyone else need to. When the solenoid is turned off and the magnetic field collapses there is a spark of current released. What can you build into the circuit to protect your switch from that collapse? I can’t remember if it’s a diode or a capacitor or a resistor...

 

[shues]

Usually a diode is used. When used in this way, such a diode is called a flyback diode.

 

[jmamrak]

Usually a diode is used. When used in this way, such a diode is called a flyback diode.

Thank you sir. Your knowledge is much appreciated.