GB498800A - Improvements in variable ratio gearing - Google Patents

Abstract

498,800. Variable - speed ratchet gearing. HEJDUK, F., and NEUMANN, J. May 20, 1938, No. 15119. Convention date, May 20, 1937. Addition to 464,214. [Classes 80 (ii) and 80 (iii)] Accurately controllable variable-ratio gearing, more particularly for use in the drive of counting mechanism 18 of a liquid flow meter, comprises a main roller free-wheel clutch 6, which always forms a direct connection between a disc 3 keyed to the driving shaft 2, and a driven element 4, which latter is also common with the driven element of a secondary roller free-wheel clutch 9, the driving disc 8 of which is adapted to be periodically advanced in relation to the driving shaft 2 so as to increase the speed of the driven shaft during such advance. In the form shown in Figs. 1 and 3, such advance is effected by a cam 11 on the disc 3 and having an arm 10, adapted to strike an adjustable fixed stop 13 so as to turn the cam 11, which acts on a flat face 121 on the disc 8, thereby advancing the latter through an arc 19 in advance of the disc 3. After the arm 10 passes the stop 13, a spring 15 returns the disc 8 to its initial position relative to the disc 3, with the flat face of the cam 11 lying on the flat face 12<1> on the disc 8. The free-wheels 6, 9 permit this return without affecting the advance in motion gained by the driven element 4. The adjustable stop 13 may be replaced by a circular track of adjustable eccentricity, engaged by a roller on the arm 10. In the form shown in Figs. 5 and 6, the periodic advance of the driving disc 8<1> of the secondary free-wheel 9<1> is obtained by a bevel toothed sector 25 pivoted on a pin 26 on the driving disc 31 of the main free-wheel 61 and engaging a similar toothed sector 24 on the disc 8<1>. The sector 25 has an arm carrying a roller 27 which tracks a stationary inclined ring 28, pivoted about an axis 29. A torsion spring 15<1> biasses the discs 4<1>, 8<1> to an initial position. The inclination of the ring 28 determines the degree of advance periodically given to the driven element 4<1>, and is automatically varied by a thermally responsive bellows 30, so as to provide an automatic correction for temperature variation of the liquid being measured.