The present invention discloses a clutch for gearbox output shaft of lawn mower, comprising gasket, worm wheel, shaft sleeve I, torsional spring and shaft sleeve II are arranged an output shaft in turn. The torsional spring is arranged inside a sliding sleeve and its two ends are arranged on shaft sleeve I and shaft sleeve II a rib-type spiral wedge is arranged at the inner hole of the sliding sleeve, and the straight claw and curved claw at the two ends of the torsional spring respectively rest against the axial plane on the one side of the spiral wedge at the inner hole of the sliding sleeve and the helicoid on the other side the worm engages the worm wheel, the shaft sleeve I is radially fixed connected with the worm wheel, the shaft sleeve II is fixed connected with the output shaft via a spring pin, the clutch release shaft is vertically arranged along the shaft sleeve II, and its upper end runs out of the upside of the box and then is fixed connected with the clutch swing arm the two ends of the tension spring are respectively hook jointed to the upside of the box and one end of the clutch swing arm, and the other end of the clutch swing arm is hinged to a clutch operational mechanism. The present invention has compact structure and small radial dimension the sliding sleeve adopts an integral structure, which facilitates processing, assembly and repair and results in low manufacture cost.
