Heavy duty transmission architecture
A transmission includes a main shaft having two or more main shaft clutches that couple gears to at least one countershaft, and an automated manual transmission coupled to the main shaft via the at least one countershaft. The automated manual transmission includes a front input shaft coupled directly to a main clutch and having a first clutch coupleable to the at least one countershaft, and a rear input shaft coupled to the front input shaft and having a second clutch coupleable to the at least one countershaft. The automated manual transmission is operable to selectively engage the first clutch and the second clutch.
1. A transmission, comprising:
a main shaft having three main shaft clutches that couple at least three gears to two countershafts;
an automated manual transmission splitter section coupled to the main shaft via the two countershafts, the splitter section comprising:
a front input shaft coupled directly to a main clutch and having a first clutch coupleable to the two countershafts via a first splitter section gear; and
a rear input shaft affixed in torsion and coupled to the front input shaft to transmit a thrust loading, the rear input shaft having a second clutch coupleable to the two countershafts via a second splitter section gear and a third splitter section gear;
wherein the automated manual transmission splitter section is operable to selectively engage the first clutch and the second clutch.
2. The transmission of claim 1 , wherein the front input shaft and the rear input shaft are coupled via the spline joint positioned between the front input shaft and the rear input shaft, the spline joint having teeth that coaxially locate a drive gear without radial displacement via a rear input shaft synchronizer clutch hub.
3. The transmission of claim 2 , wherein the spline joint is located within a bore of the first input shaft.
4. The transmission of claim 1 , the automated manual transmission further comprising:
the first clutch coupleable to the two countershafts via one clutch mechanism; and
the second clutch coupleable to the two countershafts via two clutch mechanisms;
wherein the one clutch mechanism and the two clutch mechanisms are selectively engageable via operation of the automated manual transmission splitter section using the main clutch.
5. The transmission of claim 1 , further comprising a two speed range gearbox section operable via a range clutch and coupled to the main shaft, and wherein gear selection defined by the first clutch, the second clutch, the two or more main shaft clutches, and the range clutch include 18 selectable gear ratios.
6. The transmission of claim 5 , wherein the 18 selectable gear ratios include at least one overdrive gear ratio in which a total ratio of the gears is less than 1.000.
7. The transmission of claim 5 , wherein at least one of the two or more main shaft clutches and the range clutch is a synchronized clutch.
8. The transmission of claim 5 , wherein at least one of the two or more main shaft clutches and the range clutch is a non-synchronized clutch.
9. The transmission of claim 8 , further comprising an inertial brake coupled to the at least one countershaft.
10. The transmission of claim 1 , wherein the front input shaft and the rear input shaft axially contact each other.