Patent ID: 7159493

Claim:
A driving bit linking device in a box wrench comprising: a box wrench connected to a handle at lower end, a central bore which is defined a hexagonal upper section and a circular lower section, a pair of checking slots respectively formed in opposing middle peripheries at different level, an annular collar on a lower periphery and an annular groove in upper periphery abutting upper rim for disposing a retaining ring therein; a bottom spring disposed in the circular section of said box wrench having a large diameter loose lower portion and a less diameter intensive upper portion; a pair of compression springs sequentially wrapped on outer periphery of said box wrench stopped against said annular collar and each having a transverse checking rod on top respectively inserted into said hexagonal section through said checking slots; a cap wrapped on said box wrench having an annular shoulder on upper inner periphery retained by said retaining ring; a E type bit engaged into the hexagonal section of said box wrench having an annular groove in lower periphery engaged with said transverse checking rods; a C type bit engaged into the hexagonal section of said box wrench having a rhombic concave in each angle of hexagonal body respectively engageable with said transverse checking rods.