Hydraulic unit cylinder block for integrated drive generator

An integrated drive generator comprising:

• an input shaft for driving a differential;
• said differential for providing an input drive to a generator for generating electricity, and said differential also being connected with a hydraulic unit, said hydraulic unit including a variable swash plate and a fixed swash plate, and each of said swash plates being associated with a set of pistons, a pair of cylinder blocks with one of said cylinder blocks being associated with each of said sets of pistons;
• said cylinder blocks having a shaft portion with a relatively small outer diameter and a cylindrical body portion having a larger outer diameter than the shaft portion, and said cylindrical body portion formed with a plurality of piston chambers, said cylindrical body portion extending from a first end to a second end, said second end being provided ports leading into said piston chambers and said ports having a third end and a fourth end wherein a ratio of a first distance from said first end to said fourth end to a second distance from said first end to said second end being between 0.91 and 0.93;
• wherein said ports being kidney-shaped;
• wherein said kidney-shaped ports having a width and a ratio of a depth of said kidney-shaped port, to said width is between 0.48 and 0.62;
• wherein a wear plate is affixed to said second end of said cylindrical body portion;
• and
• wherein said wear plate having ports aligned with said ports in said cylindrical body.

A method of replacing a cylinder block in an integrated drive generator comprising the steps of:

• removing an existing cylinder block from an integrated drive generator including an input shaft connected for driving a differential, said differential for providing an input drive to a generator for generating electricity, and said differential also being connected with hydraulic unit, said hydraulic unit including a variable swash plate and a fixed swash plate, and each of said swash plates being associated with a set of pistons, said existing cylinder block being one of a pair of cylinder blocks with one of said cylinder blocks being associated with each of said sets of pistons;
• replacing said existing cylinder block with a replacement cylinder block, said replacement cylinder block having a shaft portion with a relatively small outer diameter and a cylindrical body portion having a larger outer diameter than the shaft portion, and said cylindrical body portion formed with a plurality of piston chambers, said cylindrical body portion extending from a first end to a second end, said second end being provided with ports leading into said piston chambers and said ports having a third end and a fourth end wherein a ratio of a first distance from said first end to said fourth end to a second distance from said first end to said second end being between 0.91 and 0.93;
• wherein said ports being kidney-shaped;
• wherein said kidney-shaped ports having a width and a ratio of a depth of said kidney-shaped port, to said width is between 0.48 and 0.62;
• wherein a wear plate is affixed to said second end of said cylindrical body portion;
• and
• wherein said wear plate having ports aligned with said ports in said cylindrical body.