To provide a desk nails and tilling claws used to ribbing work and tilling work, to provide a nail that has the visibility and easy rib indicate when exchange. A wear proceeds to continue to use, in a position along the line after the wear of the worn portion of the exchange nail 1 has become necessary to form the ribs 7 of a substantially arc shape visible from both sides of the nail. A state in which the soil is attached in tilling confirmed easily wear condition is also to be able to carry out the exchange to the appropriate time, it is possible to prevent the waste of fuel costs and working time of the machine.BACKGROUND.【課題】畝立て作業や耕耘作業に使用するデスク爪及び耕耘爪において、交換時期を示す視認し易いリブを持つ爪を提供する。【解決手段】使用を続けて摩耗が進み、交換が必要となった爪1の摩耗部分の摩耗後のラインに沿う位置に、爪の両面から視認できる略円弧形状のリブ7を形成する。耕耘作業中の土が付着した状態であっても容易に摩耗状態が確認でき、適切な時期に交換を行うことができて、機械の燃料費や作業時間の浪費を防ぐことができる。【選択図】図1
