a new mechanism of an open - end adjustable spanner includes right latch , left latch , return spring , and control containing hairpin springs and serrated bit respectively installed by deck into an accommodation trough of a handle to create a torque transmission structure to turn a ratchet by gearing to permit easy alignment of the ratchet at the bolt or nut and avoid falling off before and after tightening or loosening up the bolt or nut ; and allow efforts - saving and convenient torque application in clamping head of a bolt or nut by selecting a proper specification of the configuration of the open end of the ratchet .