For a jaw crusher the thickness of the largest particle should not normally exceed 80–85% of the gape. Assuming in this case the largest particle to be crushed is 85% of the gape, then the gape of the crusher should be = 45.7/0.85 = 53.6 cm and for a shape factor of 1.7, the width should be = 45.7 × 1.7 = 78 cm.