Quincy Compressor model 310 help please

[pita3obn]

I have a new to me Quincy Compressor model 310. I am not sure of the year but the model # is 701348 L. The compressor runs but slows down and almost stops at 50 lbs of pressure. I took off the belts and the Baldor 2hp runs just fine. Any ideas on what might be wrong. Tnx for any help. pita3obn donald a

 

[Jay87T]

probly a bad check valve if all the high pressure from the tank is pushing back to the pump, it will be hard for it to turn.

 

[pita3obn]

Im not sure how to check but I took all the lines off and tried to make sure they were clear. Ill call Quincy Monday and see if I can just replace the values. Thanks for the thoughts.
donald

 

[larry_g]

Are you sure that the pulleys are correct for the setup? The 310 pump head is rated for 1 1/2 to 3 hp. If you are trying to drive the pumphead to fast then you will overcurrent the motor. Do you have a current probe to monitor the motor?

lg
no neat sig line

 

[pita3obn]

The motor turns slow and unlabored. I tried it with the belts removed and it about the same. Very quiet running. It starts off just fine, a slow quiet steady turn...but as it nears 50 lbs, it appears very labored and almost stops. The top valve pops and releases air and the motor runs normal for a moment and starts all over again to slow. I now do think its a valve... thanks for your help.
donald

 

[Skin]

def sounds like the head is overpressurizing due to back pressure.