Undercarriage of a crawler-type vehicle

A crawler-type vehicle undercarriage including a track frame mounted at both sides of the vehicle;

• an idler rotationally mounted at a front portion of the track frame;
• a sprocket rotationally mounted at a rear portion of the track frame;
• multiple track roller unit deposited under the track frame;
• a crawler encompassing the idler, the multiple track roller unit and the sprocket;
• the idler, the sprocket and the track frame being substantially located to line up in a straight line;
• the crawler-type vehicle undercarriage comprising:
• the idler being fixed to avoid moving upwardly or downwardly relative to the track frame;
• and
• the multiple track roller unit including an end track roller unit arranged adjacent the sprocket, the end track roller unit including a first arm having a pivoted end pivotally mounted on the track frame and a single free end, the first arm pivoting exclusively bout a first pin on the track frame so that the single free end moves in an arc passing between the pivoted end of the first arm and the sprocket;
• a second arm pivotally connected to the single free end of the first a having to free ends;
• and a track roller rotationally supported on each of the two free ends of the second arm;
• the single free end of the first arm having two parts respectively extending about both sides and below the track rollers, and the two arts of the first arm being adapted to receive an endless link chain therebetween.