An elliptical trammel (also known as Trammel of Archimedes) is used to draw the ellipses of various sizes. It is an inversion of double slider crank chain in which there are two sliding pairs and two turning pairs. Slider 1 (Link 4) moves vertically while slider 2 (Link 2) moves horizontally. The frame is kept fixed (Link 1).
Link 3 is a rod to which the pencil or router is attached to draw an ellipse.
The four links of an elliptical trammel is shown in figure