said fabric to be inserted thereunder a presser foot lifter 51 having an integrated formed adjusting protrusion 521 is pivotally connected with the bed 18 at an axis 52 and one end of the adjusting protrusion 521 abuts against a bottom face of the presser foot 50 so that the presser foot 50 will be lifted upward when the presser foot lifter 51 is manually adjusted to the right as shown in fig7 referring to fig8 and 9 wherein on the sectorial gear 33 a central tube not numbered is provided on the upper face not labeled thereof at least two lugs 331 are provided and spaced apart one of the lugs 331 is provided between the sectorial gear 33 and a top plate 332 formed integrally with the central tube and having an inclined top surface the upper part of a feed dog 35 is formed with wavy form and the lower rear part extends outward a projection 351 configured to mate the lug 331 such that the feed dog 35 is driven by the lugs 331 to swing left and right a recess 352 formed integrally with the feed dog 35 for receiving a resilient member 36 therefore it is apparent to be noted that a free end not shown of the resilient member 36 is inserted into the recess 352 of the feed dog 35 for providing a recoil force to the feed dog 35 referring to fig1 and.