Fluid transfer machine with drive shaft lubrication and cooling

A fluid transfer machine (20) includes a positive displacement, rotary-type pumping mechanism (40) driven by a drive shaft (26). The drive shaft (26) is lubricated and cooled by locating the drive shaft (26) in a primary flow path (22, 49, 50a, 50b, 42-44, 53a, 53b, 54, 23) in the machine. Fluid is directed from an inlet port (22) through a passage (49) that intersects a cavity (65) surrounding the drive shaft (26), at a location between a pair of journal bearings (60, 61). The fluid then continues through a pair of passages (50a, 50b) directly to the suction side of the pumping mechanism (40). The drive shaft (26) could also be located on the pressure side of the pumping mechanism (40). The fluid cools and lubricates the drive shaft (26) and drive shaft bearings (60, 61), and reduces the size and complexity of the machine, as additional cooling and lubrication flow passage(s) are not required.