Piston for a hydrostatic cylinder block

A piston for a cylinder block of a hydrostatic power unit comprising:

• an elongated cylindrical body having first and second ends and a center bore,
• an insert in the bore having first and second ends, the first end of the insert terminating in a spherical surface,
• the body being of a first metallic material and the insert being of a second and different metallic material,
• the body and the insert being joined together by brazing to form a cylindrical piston;
• wherein the body and insert are made by a metal injection molding process utilizing a molding material comprised, at the time of molding, of a mixture of metallic grains and a binder;
• wherein the first material has the properties of AISI 4140 and the second material has the properties of AISI 1010.

A piston for a cylinder block of a hydrostatic power unit comprising:

• an elongated cylindrical metal injection molded body having opposite first and second ends with a center bore extending therebetween;
• a metal injection molded insert having opposite first and second ends, the first end of the insert terminating in a spherical surface;
• the body being formed of a first molded metallic material comprising at the time of molding a mixture of metallic grains and a binder and after molding having the metallurgical structure and properties of a metal injection molded component;
• the insert being formed of a second and different molded metallic material comprising at the time of molding a mixture of metallic grains and a binder and after molding having the metallurgical structure and properties of a metal injection molded component;
• and
• the insert being sealingly joined to the first end of the body.