swash plate 35 is transmitted to each piston 36 through the shoes 37 and 38 and consequently each piston 36 is reciprocated in the cylinder bores 11a and 12a a front thrust bearing 39 is located in the crank chamber 31 between the inner wall surface of the front cylinder block 11 and a front end face of the boss portion 35a of the swash plate 35 a rear thrust bearing 40 is located in the crank chamber 31 between the inner wall surface of the rear cylinder block 12 and a rear end face of the boss portion 35a as shown in fig5 the front thrust bearing 39 is constituted by a front race 39a a rear race 39b and a plurality of needles 39c the needles 39c are retained between the front and rear races 39a and 39b by a retainer not shown likewise the rear thrust bearing 40 is constituted by a front race 40a a rear race 40b and a plurality of needles 40c the needles 40c are retained between the front and rear races 40a and 40b by a retainer not shown annular projections 11e and 12e are formed on the inner wall surfaces of the cylinder blocks 11.