The oil pump suction is fed fr om the oil reservoir. An oil pressu re relief valve maintains 18 to
25 psid (124 to 172 kPad) differential pressure in the system at the pump discharge. This
differential pressure can be read directly from the Local Interface Device (LID) default screen.
The oil pump discharges oil to the oil filter asse mbly. This filter is cap able of being valved close d
to permit removal of the filter without draining the entire oil system (see Maintenance sections
for details). The oil is then pi ped to the oil coo ler. This heat exch anger uses refri gerant from the
condenser as the co olant. The refrige rant cools the oil to a t emperature between 1 00 and 120 F
(37 to 49 C).
As the oil leaves the oil cooler , it pas s es th e oil pressure transducer and the thermal bulb for
the refrigerant ex pansion valve on the oil cooler. The oil is then divided, with a portion flowing to
the thrust bearing, fo r war d pinion bearing, and ge ar s pr ay . The balance then lubric at es the
motor shaft bearings an d the rear pinion bearing . The oil temperature is m eas u red as the oil
leaves the thrust and for wa rd journal bearings wi thin the bearing hous ing . The oil then drains
into the oil reservoir at the base of the compressor. The PIC (Product Integrated Control)
measures the te mperature of t he oil in the sump and maint ains the tempera ture during
shutdown (see Oil Su mp Temperature Control section). T his t emperature is read on the LI D
default screen.
During the machine start -up, the PIC will energ iz e t he oil pump and provide 15 s ec on ds of
prelubrication to t he be arings after pressure is verified before star t ing the compressor. Du r ing
shutdown, the oil pu mp will run for 60 seco nds after the compresso r shuts down for the p urpose