GEAR REDUCER

PROBLEM TO BE SOLVED: To provide a stopper structure setting a wide movable range in a gear reducer. SOLUTION: This gear reducer 4B includes the stopper structure for stopping the rotation of a gear train and formed between an engagement gear 80 rotated by receiving power transmission from the gear train (a first gear 40 and a second gear 60) and a lid case 20 for forming a housing case. The stopper structure is configured to stop the rotation of the engagement gear 80 in such a manner that a slide pin 82 formed on the engagement gear 80 is axially entered into a guide groove 23 formed in the lid case 20 and abuts on the end of the guide groove 23 on each side in a peripheral direction (an inner end 23A or an outer end 23B) by the rotation of the engagement gear 80 in both normal and reverse directions. The guide groove 23 is formed to have a length of one round or more in the peripheral direction by forming the formation position of a guide shape extending in the peripheral direction of the guide groove into a spiral shape changed in a radial direction. COPYRIGHT: (C)2011,JPO&INPIT