Portable transmission device and portable power working machine provided with the same

摘要

A power transmission device is disclosed which is capable of easily, swiftly and appropriately altering the distance between the axes of a pair of transmission wheels such as pulleys, enabling an endless belt to be kept under constant and appropriate tension without necessitating a tension roller. This power transmission device comprises an endless belt wound around a pair of transmission wheels; and a cam-type adjusting mechanism which is interposed between a driving side supporting member and a driven side supporting member and configured to adjust a distance between the axes of the wheels. This cam-type adjusting mechanism comprises a supporting shaft secured to either the driving side supporting member or the driven side supporting member and disposed parallel to the rotational axes of the wheels; and a cam rotatably secured via a manipulating boss member to the supporting shaft.