reduce the sliding resistance the charge pump is simple in construction and inexpensive to produce application_number US 74950196 A description the hst shown in fig1 includes a housing which comprises an upper half housing 1 and a lower half housing 2 which are joined to each other along a horizontal surface the housing contains the hst and forms an oil sump which is filled with operating oil for the hst a center section 5 which is l like shaped when viewed in cross section is disposed within the housing center section 5 is provided with a horizontal portion and a vertical portion and is fixed to the upper half housing 1 by mounting bolts 6 a pump mounting surface 20 is formed on the upper surface of the horizontal portion of center section 5 a cylinder block 16 constituting a hydraulic pump p of the axial piston type is rotatably disposed on pump mounting surface 20 pistons 13 are biased by springs 18 into a plurality of cylinder bores formed in cylinder block 16 pistons 13 are freely moveable into and out of the cylinder bores the heads of pistons 13 abut against a thrust bearing held to a movable swash plate 8 an input shaft 3 engages with cylinder block 16 at the axis of rotation thereof the rotational axis of input shaft 3 extends vertically input shaft 3 is supported at the upper end thereof by the upper half housing 1 and at the lower end by.