between the skirt 48 and ring 34 having radially extending circumferentially spaced expeller vanes 55 in facing relation to the seal housing 19 a seal ring 58 is mounted for circumferential extension around a forward edge of the internal wall surface of the cylindrical portion of the reservoir housing 19 in confronting relation to the expeller member 54 so as to form a valve seat for a valve member 65 a valve assembly actuator mechanism 60 is mounted on the shaft 12 between the expeller ring 54 and the sleeve 44 and comprises an outer cylindrical wall 62 and a wall portion 64 at one end of the wall 62 which terminates in an outer peripheral valve member or rim 65 which is engageable with the seal 58 axially spaced annular disks 66 and 67 are disposed at opposite ends of a governor sleeve 68 the latter being mounted for rotation with the shaft 12 the radial inner end of the disk 66 is fixed between the expeller ring 54 and a spring support sleeve 69 and the radial inner end of the disk 67 is fixed between the sleeves 44 and 68 the outer peripheral end of the disk 66 is held between an inboard lock ring 71 and inboard end of the wall 62 by circumferentially spaced bolts 70 the outer peripheral end of the disk 67 is affixed to the outboard end of the wall 62 by an outboard lock ring 72 and circumferentially spaced bolts.