outer end of support plate 92 see fig8 elongate slots 92 c which are oval arcuate shaped are open in flanges 92 b around brake operating shaft 97 bolts 96 are inserted into elongate slots 92 c thereby fixing support plate 92 onto the outer surface of the side wall of upper half housing 1 bolts 96 may be unscrewed to properly rotate flanges 92 b around brake operating shaft 97 thereby enabling balls 95 to adjust the length of time during which balls 95 ride on cam groove 97 b next explanation will be given on the construction of center section 5 for loading thereon hydraulic pump p and hydraulic motor m in accordance with fig1 through 21 center section 5 is longitudinally elongated and is provided at one side thereof with a bolt bore 5 h and at another side thereof with two bolt bores 5 h three mounting bolts are inserted into bolt bores 5 h and are used to fix center section 5 to the inner wall of upper half housing 1 in first chamber r 1 at the center of pump mounting surface 40 and at the rear and upper surface of upper half housing 1 is formed a bearing bore for rotatably supporting the lower end of pump shaft 3 a pair of arcuate ports 40 a and 40 b are open longitudinally through center section 5 around a bearing bore feed or discharge oil is communicated with cylinder block 16 through parts ports 40 a and 40 b at.