The lengths of the links comply with the conditions: A͞B=D͞C, E͞B=F͞C and A͞D=B͞C=E͞F. Upright 8 slides along guide 9 and can be fixed in various positions. This changes the positions of the adjustable links 2 and 5. Thus the mechanism can transmit rotation between links 1 and 6 wi th a variable centre-to-centre distance A͞E. In passing through the extreme position (dead point) parallel-crank linkage CBEF does not become a crossed-crank one.
$631$LW,PC$