Steplessly adjustable variable-speed hydrostatic-mechanical composite transmission

A stepless hydrostatic-mechanical composite transmission, comprising:

• an input shaft and an output shaft connectible respectively to a source of motive power and to a load;
• a hydrostatic transmission having two hydraulic machine units connected in a hydraulic circuit and each being provided with a respective shaft, a first of said units being of a variable-displacement type adjustable between a full negative setting and a full positive setting past a zero setting;
• a multishaft coaxial summing transmission having a first shaft connected to said input shaft, a second shaft, a third shaft, and gearing connecting said first, second and third shafts;
• means connecting a shaft of one of said units to said input shaft, said summing transmission having a pair of output elements;
• respective coaxial clutches connecting a shaft of the other of said units selectively to second and third shafts of said summing transmission, said coaxial clutches being simultaneously actuatable to effect rotation of said first, second and third shafts and said gearing as a unit;
• an after transmission having two further input shafts, an output member connected to said output shaft, and gearing connecting said further input shafts with the output member of said after transmission;
• and
• clutch means selectively connecting each of said output elements to a respective one of said further input shafts of said after transmission.