comprises a main shaft 56 rotatably mounted in the top of the head 12 for each push rod 18 there is a rock arm 58 extending radially from the shaft to provide a crank arm 60 having a split end conventionally connected to a connecting link 62 by a wrist pin 64 journaled in the top of the link a similar wrist pin 66 may connect the lower end of the link to the enlarged split upper end 22 of the push rod 18 the rocking motion of the shaft 56 thus effects a reciprocating motion to the push rods and hence the needles rocking motion is supplied to the main shaft 56 through means including a cam shaft 68 mounted in the head 12 below and substantially parallel to the shaft 56 and driven at one end of the machine by conventional means a circular eccentric cam 70 is secured preferably adjacent each end of the shaft 68 and rotates thereby a connecting rod 72 having a lower split end section 74 is journaled on a sleeve 76 on the eccentric cam the lower end 78 of the connecting rod is connected in a slotted arcuate arm 80 of a drive lever 82 secured at one end of the shaft 72 positioned within the slot 84 of the arm 80 is a bolt 86 connecting the connecting rod.