GB670285A - Improvements in or relating to change-speed mechanism - Google Patents

Abstract

670,285. Variable-speed gearing. SCHMITT, G., and ROGGEN, M. VAN. April 20, 1949 [April 28, 1948], No. 10445/49. Class 80 (ii). The fulcrum 5 of a lever 4 oscillated by a rotary driving crank 2 and connected by a link 6 to a driven crank 9 oppositely rotating a shaft 11 through a one-way clutch 10, is mounted on a control arm 12 so as to be movable to vary the speed ratio, the axes of the members 5, 11 being on opposite sides of the link 6 and the latter always dividing the line between the axes in such a ratio that the product of this ratio and the speed of the point of articulation 7 between the link and lever is a constant, a geometrical analysis being given to illustrate that the speed of the crank 9 may then be made to bear a constant relation to that of the crank 2 over a given power stroke, up to at least 90 degrees of arc. As shown, the necessary cycloidal path of movement of the fulcrum 5 to ensure that such relations exist for all speed ratios is approximated to the are of a circle and the arm 12 is a lever with a pivot 13 near the axis of revolution of the crank 2. The link 6 is of the same length as the distance between the points 5 and 7 so that the speed ratio may be reduced to zero by bringing the lever 4 into line with the link 6. In Fig. 8 (not shown) the lever 12 is fulcrummed about the axis of the crank 2 and the link 6 is longer than the distance between the points 5 and 7. In practice, the arrangement is quadruplicated to give a smooth power flow throughout the cycle of operations. The actual output shaft may be placed in any position, regardless of the theoretical considerations governing the disposition of the axis of the shaft 11, by connecting the crank 9 and output shaft through a parallelogram linkage. Either a reversing-gearing or a two-speed direct drive and countershaft gear may be placed behind the main gearing in series therewith.