GB631361A - Automatically variable speed transmission gear - Google Patents

Abstract

631,361. Variable-speed ratchet gearing. KOLKO, A. May 27,1947, Nos, 14072 and 14073. Convention dates, June 6, 1946 and May 21, 1947. [Classes 80 (ii) and 80 (iii)] In ratchet gearing in which the motion of the driving shaft is transmitted by a plurality of connecting rods, the driving and driven shafts are coaxial, the driving crank is resiliently loaded to the position of maximum eccentricity and the connecting rods extend radially to connect through centrifugally controlled ratchet mechanisms to layshafts parallel to the driven shaft and connected thereto by gearing. A hollow driving shaft 1 carries a crankpin 3 connected to a second crank 4 having a crankpin 5, the crankpin 3 being connected by a pinion 9 to a gear portion of a torsion bar 6 anchored by a vernier coupling 10 to resiliently urge the crankpin 5 to its position of greatest throw. The crankpin 5 carries a rotatable hub 11 to which are articulated three double connecting rods 13 pivotally connected to the crossheads 14 pivoted about the layshafts 15. The crossheads 14 are coupled by pawls 19 to ratchet wheels 17, rigid with the layshafts 15 and with the gears 20, meshing with a pinion 21 on the driven shaft. The pawls 19 have counterweights attached in a plane passing through their axes and the axes of the layshafts 15 so that the centrifugal force on the counterweights, as the crossheads 14 rotate, causes the pawls to be held in the engaged or disengaged positions, which position being determined by the tangential forces at the ends of the strokes. The end of the driven shaft is supported by rings 22 rigid with the gears 20 which bear on a ring 23 rigid with the driven shaft, the diameters of the rings being equal to the pitch circle of the intermeshing gears. By virtue of the spring loading of the crank 5 the transmission ratio is determined by the resisting torque ; when the ratio is unity or tends to be greater than unity the casing carrying the layshafts is held stationary. In a modification, Fig. 7, a pawl and ratchet mechanism is used to prevent backward rotation of the gear casing, the pawls 29 being lightly loaded by the springs 31 to engage with the toothed ring 30 rigid with the outer casing of the transmission, the pawls 29 being pivoted on the layshafts 15 and having their outer ends arranged to have a braking effect on the outer casing when in the engaged position.