A large press uses a regenerative circuit to increase the closing speed of a ram. A pressure switch signals a PLC to close a logic slip-in cartridge valve so the ram can reach maximum tonnage. The press started having trouble developing enough tonnage when the logic valve did not close when Solenoid A was de-energized.
Technicians found the logic valve sleeve and poppet to be in good shape, and replacing the pilot valve did not fix the problem. They then removed the screw-in cartridge