PROBLEM TO BE SOLVED: To perform brake turning, and to perform turning traveling with a turning radius of a size closer to a turning radius of the brake turning in a finely adjusted state.SOLUTION: This travel transmission device includes a shift transmission portion 50 interlocking with a travel device 1L on a left side and an electric motor 70 transmitting to the shift transmission portion 50. The shift transmission portion 50 is freely switched into a shift transmission state in which the travel device 1L on the left side is continuously shifted and driven at lower speed than that in a travel device 1R on a right side by electric driving force from the electric motor 70 in a worked state of a steering brake 37 for left and in a thrown-in state of a steering clutch 43 for right and a non-shift state in which a driving wheel body 13L of the travel device 1L on the left side is connected to an output shaft 36 of a transmission portion 30 for the travel device 1L on the left side in the worked state of the steering brake 37 and in the thrown-in state of the steering clutch 43.COPYRIGHT: (C)2012,JPO&INPIT【課題】ブレーキ旋回を行なうことができ、かつブレーキ旋回の旋回半径に近い大きさの旋回半径であって、大きさを微細に調整した旋回半径で旋回走行することを可能にする。【解決手段】左側の走行装置1Lに連動する変速伝動部50、変速伝動部50に伝動する電動モータ70を設けてある。左用の操向ブレーキ37が入り状態にあり、右用の操向クラッチ43が入り状態にある状態で、左側の走行装置1Lを電動モータ70からの電動駆動力で、右側の走行装置1Rよりも低速で無段階に変速駆動する変速伝動状態と、左用の操向ブレーキ37が入り状態にあり、右用の操向クラッチ43が入り状態にある状態で、左側の走行装置1Lのための伝動部30の出力軸36に左側の走行装置1Lの駆動輪体13Lを連結する非変速状態とに変速伝動部50を切換え自在である。【選択図】図2
