The present invention relates to splined rotary couplings and more particularly to splined shafts of the type utilized to couple a position-monitoring, variable rotary differential transformer (RVDT) to mechanical power drive units.
Electrical or hydraulic drive units are utilized to position the leading edge slats on commercial airplane wings. An electrical power drive unit, for example, is mechanically coupled to a rotary variable differential transformer (RVDT). The RVDT is rotated in reaction to motion of the power drive unit to provide an electrical output signal proportional to the actual position of the leading edge slat. As it is critical that the electrical output of the RVDT accurately indicates the precise position of the leading edge slat, it is absolutely necessary that no slippage or backlash occur in the mechanical connection between the power drive unit and the RVDT. It is especially important that no backlash occurs in the mechanical coupling between the follow-up mechanism and the RVDT.
It was therefore an object of the present invention to provide a positive direct drive between the shaft of an RVDT and a mechanism that follows the movement of moving parts such as the leading edge slat on an airplane wing. Further objects of the present invention were to provide a splined shaft that could easily be axially inserted and removed from, for example, a spur gear forming part of a follow-up mechanism, and to provide a splined shaft that would yield a zero backlash coupling merely upon insertion of the shaft into an internally splined gear member without further manipulation or adjustment of the shaft or external fasteners.