Angular adjustment mechanisms

An angular adjustment mechanism for adjusting the angular displacement of one component relative to another component comprising first and second internal toothed ring gears, the first and second ring gears being interconnected and adapted to be secured to one component, a third internally toothed ring gear being mounted intermediate of and rotatable relative to the first and second ring gears, said third ring gear being securable to the other component;

• the first, second and third ring gears being of the same diameter, the first and second ring gears having equal numbers of teeth and the third ring gear having a different number of teeth;
• a control gear being located coaxially within the first, second and third ring gears, and at least one planet gear being located in meshing engagement with the control gear and with the first, second and third ring gears, a tooth on each of the first and second ring gears being aligned with a tooth on the third ring gear at the point of meshing of the planet gear;
• three or more planet gears are located in meshing engagement between the control gear and the ring gears, the difference in the number of teeth of the ring gears associated with said one component and those associated with said other component being equal to or a multiple of the number of planet gears;
• the planet gears are maintained in equiangular spaced relationship relative to the control gear and the ring gears;
• and
• the control gears and the support plates have a thickness equal to the thickness of the plates defining the ring gears, and one or more control gears and a plurality of support plates are mounted on the drive shaft in appropriate relationship to the number of plates defining ring gears.