Page 1 - Troubleshooting Paper Mill Hydraulics Sample Excerpt 2

No. 3 P.M. Winder Power Supply and Rider Roll

No. 3 P.M. Winder Power Supply
and Rider Roll

Symbol Description
PT1 Pressure Transducer

This transducer converts the pressure in the full piston sides of the
rider roll cylinders into a proportional milliamp signal. A 4-20 mA
signal is normally used to indicate the pressure. The machine
controller is programmed to maintain a desired nip force on the roll as
the paper is wound. Once the pressure transducer indicates that the
desired pressure has been reached, the current to the no.18
proportional regulator coil will be controlled to allow only enough oil
through the no.13 pressure reducing relieving valve to maintain the
desired pressure.

1 Pump

This 46.7 GPM, variable displacement, externally drained, pressure
compensating piston pump supplies a volume of oil to the no. 3 P.M.
Winder circuits. The pump will deliver maximum flow whenever
pressure in the system is below the setting of the compensator. When
the pressure reaches the compensator setting, the pump will
de-stroke to deliver only the amount of oil necessary to maintain the
compensator setting in the line.

The compensator should be adjusted to 200 PSI above the pressure
required to do the heaviest amount of work. Please refer to our Basic
Hydraulic Troubleshooting manual, Hydraulics Pump section, for the
procedure for setting the pump compensator. If the compensator is
set too low, the machine will stall under heavy loads. A setting that is
too high will result in shock and perhaps damage to the machine. The
compensator valve can fail either open or closed.

Troubleshooting Papermill Hydraulics Page 31