Crawler-track unit, forest machine and forest machine assembly

A forest machine comprising a chassis, at least two modular crawler-track units each pivoted on one side of the chassis, an engine, a first power-transmission for transmitting power from the engine to each crawler-track unit and pivot bearings belonging to the power-transmission and having an inner race, an outer race and bolt holes for attachment of crawler-track unit into the pivot bearing with the aid of a sleeve shaft of the crawler-track unit, wherein each crawler-track unit comprises:

• a crawler-track frame;
• the sleeve shaft attached to the crawler-track frame and supporting the crawler-track frame in the outer race of the pivot bearing using bolts;
• a crawler mat arranged in a circulation to distribute surface pressure of the crawler-track unit;
• at least one drive wheel, mounted in first bearings in the crawler-track frame inside of the circulation of the crawler mat, to rotate and support the crawler mat;
• at least one idler wheel, mounted in second bearings in the crawler-track frame inside the circulation of the crawler mat, to support the crawler mat;
• support structure arranged in the crawler-track frame, inside of the circulation of the crawler mat, to support a part of the circulation that is against the ground, which support structure is arranged to conform according to a shape of a surface of the ground, in order to distribute surface pressure of the crawler-track unit evenly;
• a drive shaft mounted in third bearings in the crawler-track frame coaxially with the sleeve shaft to transmit power from the forest machine to the crawler-track unit and to pivot the crawler-track unit to the chassis of the forest machine,
• a shaft mounted in fourth bearings on the crawler-track frame for pivoting the drive wheel to the crawler-track frame at a distance from the drive shaft;
• and
• a second power-transmission fitted between the shaft and the drive shaft to transmit power from the drive shaft to the drive wheel.