of the cam ring 128 are alignable with the pins 124 on the side of cam ring 128 facing the pins 124 as seen in fig4 a ramp like surface 134 is formed and in normal operation the pins 124 abut the cam ring 128 on the ramps 134 under the influence of the springs 96 however when the cam ring 128 is rotated to bring the bores 130 into alignment with the pins 124 the latter will enter the former and the springs 96 will drive the nut 68 to the right as viewed in fig1 b to provide the feathering action for the blades 20 as mentioned previously to facilitate entry of the pins 124 into the bores 130 the pins 124 may be provided with reduced diameter slightly tapered frusto conical ends 136 as seen in fig4 the cam ring 128 is rotatably received within the interior 138 of an annular flange 140 on part of the base structure 92 as seen in fig3 at one location thereon the annular flange 140 is provided with a large diameter recess 142 which merges with a small diameter bore 144 an actuating rod 146 is disposed within the bore 144 and extends out of the same and through the recess 142 the rod 146 is pivotably secured to the cam ring 128 by means of a pivot pin 148 oppositely of the pin 148 a nut 150 and washer 152 capture and compress a coil spring 154 against a shoulder 156 at the point of union of the recess 142 and the bore 144 as can be seen from fig3.