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Link 1 is connected by turning pair A to the fixed link and by sliding pair B to link 2 which, in turn, is connected by screw pair C to the fixed link. Link 2 has a prismatic outside surface and internal thread. Rotation of link 1 is converted into screw motion of link 2. When link 1 is turned through the angle ϕ₁, the displacement of link 2 along axis y-y is s₂=h_C(ϕ₁/(2π)) where h_C is the pitch of the thread of screw pair C. It is taken with a plus sign for right-hand thread and with a minus sign for left-hand thread.