| 摘要 |
The ring spanner has a handle (1) and a head (2) with an aperture (3) in which a cylinder (5) is inserted. Grooves (6) of part-circular cross-section are formed at regular intervals round the periphery of the cylinder. - An oblique bore (8) extends to the aperture from one side of the handle. It contains a ball (9), spring-loaded into engagement with one of the grooves. |
