| 摘要 |
<p>The device is connected to the front of a tractor to assist in earth levelling, and has two twin wheels (2) smaller in diameter than the front wheels of the tractor. These are carried by a frame which can be adjusted so that the front wheels are lifted from contact with the ground, and the earth tends to be squeezed between the twin wheels. This frame (1) has a base (3) attached by hinges (4) forming a horizontal pivot axis and has a rectangular structure (7) at the rear, tilting about a parallel axis (8), which also forms the connection with the tractor. At the centre is a traction bar (9) attached by a hinge to the top of the structure and at the other end to a vertical wishbone (5), the whole forming a parallelogram linkage. This linkage is then swung by a diagonal double action piston and cylinder (11) so that the front of the tractor is lifted, and all the weight is supported by the twin wheels.</p> |
