No-load-run strap release control mechanism for a strapping machine

A no-load-run strap release control mechanism for a strapping machine, comprising a transmission cam, a machine frame, a slide carrier reciprocated horizontally on said machine frame, a welding mechanism pivoted to said machine frame and driven by a tensile spring to force a guide wheel into contact with said transmission cam, a strap guiding mechanism consisting of a strap guiding arch and a set of guide rollers, said set of guide rollers being driven to let off or take up a polypropylene packing strap, said strap guiding arch having an input end and an output end, the set of guide rollers having an output end for guiding said polypropylene packing strap into the input end of said strap guiding arch, the output end of said strap guiding arch being disposed above the output end of said set of guide rollers, wherein a brake mechanism is installed in said frame to stop said welding mechanism from operating when said polypropylene packing strap is moved for in no-load-run, said brake mechanism comprising a holder mounted in the output end of said strap guiding arch and connected to said frame by a tensile spring, a movable member, a link pivotably connected between said holder and said movable member, a control switch disposed at one side by said link and controlled to operate when said link is oscillated, a timer controlled by said control switch, and a holding-down device controlled by said timer, said holding-down device comprising a solenoid valve controlled by said timer, and a hook moved by said solenoid valve to hold down said welding mechanism when said solenoid valve is energized by said timer.