Improvements relating to zeroizing means for indicating mechanism

摘要

526,018. Zeroizing-mechanism. PRECISION METERS, Ltd., and HORTON, F. March 0, 1939, No. 7302. [Class 106 (i)] Means for zeroizing the indicating mechanism of a liquid dispensing apparatus comprise a finger knob and clutch means operative to rotate the spindle of the indicating means under normal usage but ineffective in the event of the knob being jerked or rotated above a predetermined speed. As shown in Fig. 1 the knob comprises an outer part 4 and an inner part 5 which serves as one of the clutch members. The other clutch member 2 is supported on the part 5 by a ball race 8 and carries the indicating spindle 3 by a screwed sleeve 7. The member 2 has an axial extension 9 engaging a ball 11 in the knob part 4 and is formed with recesses 12, Fig. 2, for engaging with balls 14 to form a driving connection during the zeroizing operation. Diametrically opposed recesses 13 in the inner part 5 of the knob receive the balls if the knob is rotated too quickly.