transmission gear boxes 14 and n f equals the number of vane faces constituting the set of vanes 12 rotated by a single transmission m is the angular over ride of the drive motor as it stops and 360 u00b0 is one revolution of the input drive shaft hence in a conventional construction wherein three vanes 12 are mounted upon each transmission 14 and thirty transmissions are used to constitute a sign 10 and wherein there is a 1 u00b0 over ride due to stopping of the drive motor the angle u03b1 will be equ2 if only two vanes 12 are mounted upon a transmission u03b1 will equal 5 93 u00b0 and if four vanes 12 are mounted upon a transmission u03b1 will equal 8 87 u00b0 the circumferential length of the cam surface 54 fig3 is such that the cam surface 54 will engage the detent surface 56 and lift the detent 44 prior to the partial gear teeth 52 engaging the teeth 50 of the circular gear 40 driving the vane sign support shaft 38 thus with the detent 44 lifted from its previously aligned detent opening 48 the vanes 12 will begin rotating due to their interconnected drive shafts and in a three vane set the 7 9 u00b0 difference between adjacent transmissions 14 will sequentially reveal the vane surfaces from the left side of the sign 10 fig1 to the right because there is a 7 9 u00b0 difference in the angular rotation between each transmission during movement the number of teeth 52 are such as to rotate the vane sign support.