Patent ID: 7913581

Claim:
A multiple speed ratio power transmission mechanism for an engine powered vehicle having multiple gear ratio gearing, a mainshaft and range gearing with low and high ratio ranges; two separate countershaft assemblies including separate countershafts, and multiple mainshaft gears on the mainshaft, each countershaft assembly having at least one countershaft gear element engageable with separate mainshaft gears; two power input shafts; each power input shaft being drivably geared to a separate one of the countershaft assemblies; dual clutches for selectively establishing and disestablishing driving connections between an engine and each power input shaft; and gear ratio change clutches for selectively establishing torque flow paths through the multiple gear ratio gearing; one torque flow path from the engine to one countershaft assembly and through the multiple gear ratio gearing being established as another of the torque flow paths from the engine to the other countershaft assembly is preselected; the dual clutches disestablishing the one torque flow path and establishing the other torque flow path as the dual clutches are respectively engaged and disengaged; the range gearing including high and low range clutches for selectively establishing the low and high ratio ranges; the low ratio range being established and the high ratio range being preselected during torque delivery through the multiple gear ratio gearing; the low ratio range being disestablished and the high ratio range being established as the dual clutches are engaged and disengaged to condition the transmission mechanism for high range operation, the high and low range clutches being adapted to preselect high range operation during low range operation when torque delivery through range gearing for high ratio range operation is interrupted whereby a smooth transition from low ratio range operation to high ratio range operation is made during a change in torque delivery paths through the dual clutches.