a pump casing 112 a rotor eccentrically in the casing 114 a vane loosely fitted in a radial slot 114 in the rotor 115 a suction port 116 a delivery port and the numeral 117 designates a check valve provided on the delivery port the casing 111 as shown in fig1 is cylindrical and has side covers 120 and 121 secured to the opposite sides thereof by bolts 122 and 123 with side plates 118 and 119 interposed therebetween the rotor 112 as shown in fig1 has a shaft 124 integral therewith mounted in bearings 125 and 126 in the side covers 120 and 121 so that it is rotatable in an eccentric position in the casing 111 in addition the shaft 124 has a driving pulley 127 secured to one end thereof thus the driving of the rotor 112 is effected by said driving pulley as shown in fig1 the vanes 113 loosely fitted in the radial slots 114 in the rotor 112 have rolling members 128 and 129 on the opposite sides of the inner edges thereof the rolling members 128 and 129 are constituted by such members as microbearing and mounted on shafts 131 and 132 projecting from the opposite sides of base plates 130 riveted to the inner edges of the vanes 113 when the vanes 113 are to be assembled into the rotor 112 the base plates 130 are riveted to.