無銷推進器安裝於艉軸，是利用錐體表面接觸，完全依靠摩擦阻力，在 無滑動的情況下傳遞動力。推進器裝妥在軸上之後’常年浸泡在海水之中’
銅質推進器的膨脹係數大於鋼軸的膨脹係數，由於海水溫度每年四季有不同 變化，熱時趨鬆，仍應保持足夠的摩阻扭矩，冷時趨緊，推進器轂的内緣張 應力增加，仍應在安全範圍之内。國際船級協會聯合會（IACS)在1978年有 統一規定，僅部份船級協會，大同小異的採用以公式訂出規範。本文亦以稍 異之觀點，整理訂出安裝之許範圍，以便採納為規範使用。

The filling of a keyless propeller on Uni shnfl conc is lo nuikc use of the contact friction between the maling surfaces for power iransmission When the keyless propeller is filled on tail shaft, ii is submerged in sea water all ihc >cnr round. When sen Icinpcraiurc rises, llic conlacl surfacc lends to bccoaic loose bui ii is still sufficiciil lo rcsisl the Inuisiniltcd poucr iigninst slip. When sea Icinpcrnturc drops, the conlact surfacc tends to bccomc more lighl and (luis increases the hoop slicss of propeller hub inner surfacc though it is kcpl at a safe level. InlcrnnlionnI Association of Classificalion Sociclicss (IACS) publisahcd a unified requirements in 1978. Only sonic of the Sociclics adopted the requirements in (iicir Rules ui(h minor cJuuigcs. In (Ins paper, llic mitJicr lias devdoped Ihc foniiiilac lo Jimii (Jie ruling ranges in line with ihc idea of IACS but ihc expressions arc somewhat different for praclical use and inclusion in CR Rules when llicy arc revised.