| 摘要 |
A grass trimmer has an elongated operation rod, a prime mover mounted on one end of the operation shaft, a transmission shaft extended through the operation rod, a gear box connected at its one end to the other end of the operation rod, and a cutting blade member connected to a blade driving shaft projected from the other end of the gear box, the transmission shaft and the blade driving shaft being drivingly connected to each other through gears within the gear box. The gear box 5 is composed of a plurality of steel sheets 7,8 which are shaped beforehand to define, when assembled together, a hollow 17 of a circular cross-section and to have longitudinal flanges 9,9 and 10,10. The steel sheets 7,8 are joined to each other to form the gear box in one body by hemming along the flanges 9,9 and 10,10 such that the flanges are superposed and folded one on the other to form fold-back portions 11,11 along the length of the gear box 5. The fold-back portions effectively increases the stiffness of the gear box 5 and, hence, improves the resistance of the same against impact. |
