ABSTRACT
Already demonstrated in chapter 4, for small displacements, the four bar link with equal length supports provides a simple mechanism for achieving an approximate rectilinear motion. Probably the two most commonly encountered forms of this are the notch and leaf-type mechanisms shown in figure 5.1. As stated in section 4.1.5, if the upper platform of the parallel spring mechanism is perfectly rigid, the optimal drive should be positioned mid-way betWeen the moving and stationary platforms. When the moving platform has finite rigidity additional considerations may be necessary, some of which are outlined in section 5.2. Issues associated with the manufacture and assembly of these types of flexure are discussed in chapter 8. To introduce the reader to some of the analytic methods for assessment of linear spring performance, the following two sections consider the leaf and notch type mechanisms respectively. In many cases, similar analytic models can be developed for mechanisms comprised of either flexure type. Because of this, the reader can assume that where analysis is not included for one type, it is safe to follow the procedures for the other.
