Transmission for vehicle

A transmission for a vehicle, comprising:

• a first input shaft selectively receiving power from an engine;
• a second input shaft continuously receiving power from the engine;
• a first output shaft arranged in parallel with the first input shaft and the second input shaft;
• a differential drawing power from the first output shaft and a second output shaft;
• a first shift unit arranged between the first input shaft and the first output shaft, and between the first input shaft and the second output shaft, and configured to perform a series of desired gear shifts there between;
• a second shift unit arranged between the second input shaft and the first output shaft, and between the second input shaft and the second output shaft, and configured to perform a series of duplicate gear shifts there between, each duplicate gear shift having a gear ratio substantially identical to at least one gear ratio of the desired gear shifts of the first shift unit;
• and
• one or more one-way clutches arranged in a power transmission line for transmitting power from the engine to the differential through the second shift unit and configured to transmit the power from the engine to the differential through the one-way clutches,
• wherein the first input shaft is a hollow shaft fitted around the second input shaft and connected to the engine through a clutch,
• wherein among the gear ratios of the desired gear shifts performed by the first shift unit and of the duplicate gear shifts, a largest gear ratio of the gear shifts of the first shift unit is substantially identical to a largest gear ratio of the duplicate gear shifts, and
• wherein a lowest gear ratio of the duplicate gear shifts is larger than a lowest gear ratio of the gear shifts of the first shift unit.