is received on the crankshaft and has a circumferentially extending recess a radially extending drive pin is secured in the crankshaft and coacts with the ends of the recess to position the rotor in accordance with the direction of rotation of the shaft application_number US 33771794 A description in fig1 the numeral 10 generally designates a semi hermetic reciprocating compressor having a casing 12 pump housing and bearing member 14 is bolted to casing 12 by bolts 16 pump housing and bearing member 14 has a first bore 14 1 and a second bore 14 3 coacting with bore 14 1 to form a shoulder 14 2 bore 14 3 is connected to oil supply chamber 22 which is in turn connected to and fed by oil inlet structure connected to a sump not illustrated additionally pump housing and bearing member 14 has a pair of bores 14 4 and 14 5 for respectively receiving cylindrical vanes 42 and 44 spring 43 is retained in bore 14 4 by spring retainer 46 and biases vane 42 into tracking sealing contact with annular rotor 30 similarly spring 45 is retained in bore 14 5 by spring retainer 47 and biases vane 44 into tracking sealing contact with rotor 30 crankshaft 24 has a first portion 24 1 supported by a bearing defined by bore 14 1 contained in member 14 and an overhung portion 24 2 which is received in and extends through annular rotor 30 pump rotor 30.