| 摘要 |
<p>The blade (1) mounted on the driving shaft of a lawn mower so as to create a current of air can have a flat roof with holes (2, 3) through it for securing bolts. The remainder is approximately triangular, and has four radial ribs (6 to 9) along it. These can be formed by casting, moulding, pressing etc., and extend in the direction of flow. They project from one side of the blade and can also extend beyond its sloping edge (10) in a direction opposite to the direction of rotation. Plastics or fibre reinforced plastics may be used for the material. The blade may consist of flat sections sloping at different angles, or it may be curved. At the junction lines (4,5) the sections may slope at an angle between 0 and 40 deg.</p> |
