| 摘要 |
A precision screwdriver having a handle with a rotatable portion consisting of a shaft, a handle, a thrust ring and a rotatable cap. The handle has a cylindrical portion with a raised edge formed on its outer surface, and an internal cavity. The rotatable cap is equipped with a hole therethrough for holding a bearing in the form of a single ball. An internal groove disposed at near the hole serves a securing function when the raised edge of the cylindrical portion of the handle is fitted to the rotatable cap internal groove. A concave securing plate with a hole therethrough is disposed on the outer edge of the rotatable cap hole. The securing plate serves to position the bearing with suitable surface exposed through the securing plate hole. Thus, the rotatable cap can be fitted onto the cylindrical portion of the handle and properly secured by mating the raised edge with the internal groove. The bearing is inserted into the rotatable cap hole through the top of the rotatable cap and is retained between the handle cavity and the rotatable cap by the securing plate. In use, the index finger is placed on the exposed bearing which serves as a rotating point. Consequently, when pressure is applied, the shaft and handle revolve independently of the rotation of the bearing and the rotatable cap.
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