Mechanical rotary position setting appts. - has adjustable circular plate supported by three conical bearings containing inelastic balls with flexible coupling to baseplate

摘要

The mechanical positioning device comprises a fixed lower circular plate (P1) covered by an adjustable upper circular plate (P2), connected together by a spring link (1) along the common centre-line and having its ends attached to horizontal pegs (4, 5) in the plates. The upper plate contains three conical bores (L1, L2, L3) with vertical axis, each of which retains a ball (B1, B2, B3) resting in a selected group of 3n parallel sided grooves (R1, etc). The face of each groove in contact with a ball bearing makes an acute angle (Theta 1) with its complementary member, and this is greater than the included angle (theta 2) of the cone. Typically, these angles are 90 deg. and 60 deg. respectively. The azimuth angles between the three ball positions are 120 deg. each.