mycom 4wb unloading problem

[samlee12]

I have a problem with a Mycom 4wb compressor.Upon start up it will run 50% unloaded for the one minute time delay then run at 100% load but when the plc tries to unload back to 50% the compressor will not unload took apart compressor and checked sleeves for proper setting and check with the threaded rod screwed into hole for force unloading mechanism piston and arm to forward position.i have not found anything wrong with the compressor or loading mechanism. oil pressure is runing at 30 psi, cheked unloader solenoid, and it works checked oil bypass line checked orifice tee for oil supply to unloaders there is no blockage but the oil seems to be staying in the unloader chamber even when the oilbypass solenoid is energized.Has anybody ever had such aproblem, i know these mycom compressors like the back of my hand, have had other mechanics look at compressor and nobody can figure out problem even called mycom and they have never seen this problem before.I suspect that maybe the unloader arm spring could be weak and not pushing enough to push the oil out of chamber but have checked the spring and there seems to have some tension as it will unload when the threaded rod is un screw from hole.

[RANGER1]

samlee12 ,

Have seen it when unload cam rings get a notch where pins sit when fully loaded .
This can be caused by vibration and pin bounce up and down on one spot causing hole , then can stick (replace cam ring ).
Whether this is your problem ?
On 4WB you could possibly put unload solonoid on other bank as it usually has stop valve for manual unloading (maybe you should check if it works properly first to avoid confusion ) .
Other possibility is u/load solonoid is not opening fully for some reason . You could take internals out to test .
I guess unload pins go down when threaded rod is screwed in ?
Is there any carbon or deposits around cylinders/cam rings ?
Let us know what you come up with ,

[Andy]

I have a problem with a Mycom 4wb compressor.Upon start up it will run 50% unloaded for the one minute time delay then run at 100% load but when the plc tries to unload back to 50% the compressor will not unload took apart compressor and checked sleeves for proper setting and check with the threaded rod screwed into hole for force unloading mechanism piston and arm to forward position.i have not found anything wrong with the compressor or loading mechanism. oil pressure is runing at 30 psi, cheked unloader solenoid, and it works checked oil bypass line checked orifice tee for oil supply to unloaders there is no blockage but the oil seems to be staying in the unloader chamber even when the oilbypass solenoid is energized.Has anybody ever had such aproblem, i know these mycom compressors like the back of my hand, have had other mechanics look at compressor and nobody can figure out problem even called mycom and they have never seen this problem before.I suspect that maybe the unloader arm spring could be weak and not pushing enough to push the oil out of chamber but have checked the spring and there seems to have some tension as it will unload when the threaded rod is un screw from hole.

Hello samlee

from memory Mycom energise to unload, .

Could be quite a few things, form my experience with compressors it is usually something simple.

I suppose I would blow out the loading pipes to check for restrictions and switch the solinoides around. I would also load and unload using a different electricl source (a plug and a power lead) just to be sure.

Then it would be time to change out the loading parts in the compressor.

Hope this helps. Kind Regards Andy

[samlee12]

samlee12 ,

Have seen it when unload cam rings get a notch where pins sit when fully loaded .
This can be caused by vibration and pin bounce up and down on one spot causing hole , then can stick (replace cam ring ).
Whether this is your problem ?
On 4WB you could possibly put unload solonoid on other bank as it usually has stop valve for manual unloading (maybe you should check if it works properly first to avoid confusion ) .
Other possibility is u/load solonoid is not opening fully for some reason . You could take internals out to test .
I guess unload pins go down when threaded rod is screwed in ?
Is there any carbon or deposits around cylinders/cam rings ?
Let us know what you come up with ,

the solenoid that is on the unloader is new already though of problem with solenoid recommended port size was 0.109" port and replaced with 0.200" port did not make a difference. But to your first point when the compressor was overhauled i did notice the unloader cam ring did have a notch in it but never though it would be enough to cause it to jam up. Great idea thanks i will replace the cam ring right away. I will let you know if it works out.

[samlee12]

Hello samlee

from memory Mycom energise to unload, .

Could be quite a few things, form my experience with compressors it is usually something simple.

I suppose I would blow out the loading pipes to check for restrictions and switch the solinoides around. I would also load and unload using a different electricl source (a plug and a power lead) just to be sure.

Then it would be time to change out the loading parts in the compressor.

Hope this helps. Kind Regards Andy

have already taken apart all lines to check for restrictions and have tried plugging in solenoid to different power source. I am usually not in the habit of replacing parts unless the problem suggests there is some thing broken. it is a really simple unloading mechanism not many parts could fail.had another tip from someone who suggested problem could be with notches worn in came ring from the pins vibrating. when the compressor was torn apart i did notice these notches and i am going to replace cam rings cause this does make sense that the notches are causing the unloader to stick, Thanks for your reply.

[IceMan_4000]

This Machine is a WB so it could be up to 15-20 years old

attached is a page out of the WB manual

In my experiances with the unloaders in the WB Part #145 is the cause of most of the issues. This little piston spends its life moving and wearing out.

if it gets too worn it will jam as it the spring pushes it to unload.

If you have changed your camrings and pins and that did not work. Replace this piston. when I was still in the service side of the world I would change these little pistons on old machines all the time.

Just a thought

[nh3wizard]

IceMan 4000, I opened the pdf and there wasnt anything but;

ERROR: undefined
OFFENDING COMMAND: get
STACK:
/quit
-dictionary-

-mark

Is this problem on my end?

[IceMan_4000]

IceMan 4000, I opened the pdf and there wasnt anything but;

ERROR: undefined
OFFENDING COMMAND: get
STACK:
/quit
-dictionary-

-mark

Is this problem on my end?

Nope one on my end

Fixed it

simple screen shot from manual just of unloader assemble

[jose regueiro]

spanish
XXX.mayekawa.es/Descargas/MYPRO_CPI_Instrucciones_de_cableado.pdf
for CPI/E

[RANGER1]

samlee12

What happened ? Have you had a chance to do it yet .

[samlee12]

I have changed the cam rings and have changed the unloader piston and spring but have not had the time to go back to the plant to run test it. I was so busy I had to get another tech. to finish putting it back together, why he did not try it out i don't know, lazy i guess. I will get the chance to go back sometime this week, i promise to let you guys know.

[IceMan_4000]

Samlee12

How old is this compressor?

after 10 years in Canada you can apply for the Xchange program.

Get your customer a new one

[samlee12]

changed the cam rings,unloader piston and spring, compressor unloaders are now working properly. Thanks for the help.

[IceMan_4000]

Awesome

Glad to hear its purring like a kitten again