range for a knitting operation those elements make an action of a safety device and if the shaft 22 is positioned such that it is not detected by either one of the sensors 26 27 that is if the presser bar 18 is positioned at an intermediate position which does not coincide with the advanced position nor with the retracted position a stop motion operates so that the machine is stopped an arbitrary position from a shallowest position 22a corresponds to a position for the transfer and a position just below on the back side of needles to a deepest position 22b at which the shaft 22 can be detected by the sensor 26 can be obtained by varying the number of pulses of a stepping motor by such variation of the position the advanced position of the presser bar 18 can be varied within a range indicated by x in fig2 as shown in fig2 the rocking arm 13 makes a crank motion around a fulcrum provided by the shaft 16 together with the presser bar supporting arm 15 but when at the retracted position of the presser bar 18 some external force is applied from below to above with respect to a longitudinal direction of the presser bar supporting arm 15 the rocking arm 13 may be moved to a position near or beyond a dead point due to the damping action described above and there is the possibility that a crank motion may not be performed any more a stopper 28 is provided to prevent such possibility the brush supporting member 9 is constituted in the following manner a gear 32 which meshes with.