Heavy duty transmission architecture design

A transmission assembly comprising:

• a) an input shaft assembly including an input shaft extending between a first end and a second end;
• b) an output shaft assembly including an output shaft;
• c) a power train gear assembly including at least one mechanism for changing a gear ratio between the input shaft assembly and the output shaft assembly, wherein the power train gear assembly includes a head set gear connected directly to the input shaft proximate the first end;
• and
• d) a bearing assembly including a first bearing assembly supporting the head set gear and a second bearing assembly supporting the input shaft proximate the second end, wherein the second bearing assembly and the second end of the input shaft are located within an internal cavity of the output shaft.

A transmission assembly comprising:

• a) an input shaft assembly including an input shaft extending between a first end and a second end;
• b) an output shaft assembly including an output shaft;
• c) a power train gear assembly including at least one mechanism for changing a gear ratio between the input shaft assembly and the output shaft assembly, wherein the power train gear assembly includes a head set gear connected directly to the input shaft proximate the first end;
• and
• d) a thrust mechanism for neutralizing opposing axial loads generated between the input shaft and a main shaft.

A transmission assembly comprising:

• a) an input shaft assembly including an input shaft extending between a first end and a second end;
• b) an output shaft assembly including an output shaft;
• and
• c) a geartrain assembly for changing a gear ratio between the input shaft and the output shaft, the geartrain assembly including:
• i) a head set gear fixed to the input shaft, the head set gear being intermeshed with a first countershaft gear and defining a first internal drive interface;
• ii) a drive gear intermeshed with a second countershaft gear and defining a second internal drive interface;
• iii) a main shaft intermeshed with the output shaft, the main shaft defining a first external drive interface;
• and
• iv) a clutch assembly including a sleeve member slidably disposed about the main shaft, the sleeve member defining a third internal drive interface engaged with the first external drive interface, the sleeve member defining a first external gear spline for engagement with the first internal drive interface and a second external gear spline for engagement with the second internal drive interface, wherein the first external gear spline has a first diameter and the second external gear spline has a second diameter different from the first diameter.