through fig6 d the second embodiment of the present invention is described with reference to fig3 the same parts as the first embodiment have the same numerals and their explanation is therefore omitted a first gear 181 fixed on a driving shaft 81 and a second gear 151 fixed on a crank shaft 51 by a bolt 152 have the same number of teeth so that the driving shaft 81 and the crank shaft 51 rotate at the same rotational frequency a balancer 182 is fixed at the end of the driving shaft 81 by a bolt 184 the first gear 181 has a balancer 183 the eccentric directions of the balancer 182 and the eccentric portion 52 are opposite and the eccentric directions of the balancer 183 and the eccentric portion 52 are the same the present embodiment reduces the frontal and radial cross sectional areas besides having the benefits produced by the first embodiment additionally the use of gears allows shaft 81 to be located during manufacture at any place along an arc extending from side to side of the compressor thereby providing more flexibility in location of the compressor in the engine room of a car the third embodiment of the present invention is described with reference to fig5 the crank shaft 51 is a cantilever supported by a ball bearing 123 and does not penetrate through.