Torsion screwdriver

A torsion screwdriver comprising:

• a positioning sleeve formed with an axially extending locking hole that is defined by a plurality of adjacent locking sides interconnected by adjoining corners, said positioning sleeve having a tubular part that is formed with said locking hole, a radial outward flange that is disposed on a front end of said tubular part, and an annular skirt that extends forwardly from an outer periphery of said radial outward flange, said annular skirt being formed with an inward projection;
• a locking tube disposed in said positioning sleeve and formed with an axial sleeve-receiving hole and a plurality of axially extending rod-retaining slots communicated with said sleeve-receiving hole, said locking tube having a front end formed with an annular outward flange that is confined by said annular skirt;
• a plurality of locking cylinder rods received in said rod-retaining slots, respectively;
• a curved spring strip having a first end connected to said annular outward flange of said locking tube, and a second end abutting against said inward projection on said annular skirt of said positioning sleeve;
• a rotary member disposed adjacent to said front end of said locking tube and coupled to said annular outward flange of said locking tube for co-rotation therewith, said rotary member being formed with a through hole aligned with said sleeve-receiving hole of said locking tube;
• a coupling sleeve disposed in said sleeve-receiving hole of said locking tube and in contact with said locking cylinder rods, rotation of said positioning sleeve in a first direction resulting in engagement of said locking cylinder rods with said locking sides to permit co-rotation of said coupling sleeve with said positioning sleeve, rotation of said positioning sleeve in a second direction resulting in alignment of said locking cylinder rods with said adjoining corners to disengage said locking cylinder rods from said locking sides and result in idle rotation of said positioning sleeve relative to said coupling sleeve, said coupling sleeve being formed with an axially extending coupling hole, and having a front end portion that extends into said through hole in said rotary member and that is retained rotatably on said rotary member;
• and
• a bit-driving shaft extending into said coupling hole in said coupling sleeve, one of said bit-driving shaft and said coupling sleeve being formed with a radial key projection, the other one of said bit-driving shaft and said coupling sleeve being formed with an axially extending keyway that engages slidably said key projection to couple removably and non-rotatably said bit-driving shaft and said coupling sleeve.