An assembly for converting motion comprises a first arm rotatable at a first position about a first fixed pivot; a second arm rotatable at a first position about a second fixed pivot; a third arm linked at a first position to the second arm at a second position on the second arm, the third arm being linked at a second position to the first arm at a second position on the first arm; wherein one of the first and second positions on the third arm is moveable and the other of the first and second positions is fixed relative to the third arm; and a connecting arm extending between the first arm and the second arm, the connecting arm pivotably connected at a first position to a third position on the first arm and pivotably connected at a second position to the second position on the second arm.