for interlocking the trigger 20 with the latch 9 23 designates a stopper pin for preventing excess pivoting of the latch 9 in the downward direction in the input side the parts corresponding to the parts 20 to 23 are provided not shown to form a pair with the latch 8 in fig1 fig5 shows the condition of detaching the latch pin 7 from the latch 9 by upwardly operating the releasing lever 21 fig6 to 8 are respectively schematic side views for showing relations between the input shaft 2 and the output shaft 3 from the side of the output shaft the rings at the central part show clutches interlocking each other and the parts a b show the projecting parts in these figures circles show the latch pins 6 7 and circles show positions of the crank pins 4 5 the upper views show the input shaft 2 and the lower views show the output shaft 3 and the shafts are turned in the arrow line direction fig6 shows the condition of releasing energy from the springs 12 13 in the input side and the output side to open the electrode as in fig1 fig7 shows the condition of storing energy into the spring 12 in the input side to open the electrode as in fig2 fig8 shows the condition of storing energy into the spring 13 in the.