connecting jack 19 and the ridges of the serration 21 ride over the raised end of the plate spring 4 to enable the connecting jack 19 to rise further relative to the sinker jack 3 consequently as shown in fig5 a and 5 b the sinker jack 3 is retained at its uppermost position and the connecting jack 19 is raised by the actuator shaft 17 to raise the needle 1 to the clearing position c when the load on the rocking sinker 8 in holding down the fabric or in preventing the raising motion of the old loop 12 is excessively large the resistance against the upward movement of the sinker jack 3 increases beyond the raising force applied to the sinker jack 3 by the engagement of the serration 21 of the connecting jack 19 and the plate spring 4 even before the sinker jack 3 is stopped by the upper stopper 6 and consequently the connecting jack 19 starts moving upward relative to the sinker jack 3 that is as shown in fig6 a and 6 b the connecting jack 19 is raised to its uppermost position by the actuator shaft 17 to raise the needle 1 to the clearing position c while the sinker jack 3 remains stopped at the position where the same has been stopped by the load on the rocking sinker 8 in holding down the fabric or in preventing the raising motion of the old loop 12 and consequently the fabric and the old loop 12 are not damaged the power transmitting motions of the sinker jack 3 and the rocking sinker 8 during the course of lowering the needle 1 by the connecting jack 19 connected to the actuator shaft 17 from.