Power transmission system in a tractor

摘要

A power transmission system in a tractor having a travelling drive sub-system for driving wheels and a PTO drive sub-system for driving working machines. A transmission case is provided with a single input shaft connected to an engine, and the travelling drive sub-system and the PTO drive sub-system are respectively led out from the input shaft separately. The travelling drive sub-system is connected to the input shaft via a main clutch, and is composed of a multi-stage speed-changer having a plurality of speed-changer clutches. The PTO drive sub-system is connected to the input shaft via a PTO clutch that is different from the main clutch, and at the rear portion of the PTO drive sub-system is provided a power transmission switching apparatus which can selectively transmit power to a plurality of PTO shafts.