| 摘要 |
<p>1,220,652. Mowing machines. HAYTERS Ltd. 16 March, 1970 [2 April, 1969], No. 17412/69. Heading A1F. A rotary grass-cutting machine has a vertical driving shaft 10 with a threaded bore 15 in its lower end. An apertured plate 13 with a mounted sleeve 12 is drivably secured to this shaft and is dished concavely as viewed from the underside. A double-ended cutter blade 17 is stressed against the underside of the plate using a double-shouldered spacing collar 22, a washer 24, and screw 16 which screws into the shaft. The radius of curvature of the blade is slightly greater than the radius of curvature of the plate resulting in a limited frictional surface contact between the two. If the blade meets an obstruction this friction is broken and the blade does not revolve with the plate, thus reducing serious damage.</p> |
