GB772638A - Improved vacuum milking apparatus - Google Patents

Abstract

772,638. Pulsators. AYRE, E. R., and POOL, K. R. March 28, 1955, No. 8944/55. Class 84. [Also in Group XL(c)] The Figure shows a timing circuit for controlling pulsators in a vacuum milking apparatus in which the frequency of the cycle and the on/ off ratio of the pulses may be separately controlled. A multi-vibrator comprising tubes 5, 6 inter-connected between anode and control grid has a relay A1 in its anode circuit so that by adjustment of the values of capacitors 10 and 12 the make to break ratio of relay A1 may be changed, and by adjustment of the ganged potentiometers 13, 14 the pulse repetition frequency of the multi-vibrator may also be varied. Contacts A1 of relay A1 control the D.C. supply from rectifier bridge 20 to a higher current relay B the contact of which controls the D.C. supply to the pulsators in the vacuum milking line. Indicator lamp 15 is connected across the circuit and a fuse 17 is in series with the load, fuse lamp 18 and limiter resistor 19 are connected so that if fuse 17 blows indicator lamp 18 will light up ; lamp 15 is similarly illuminated while relay B is operated. The multi-vibrator should operate at a frequency not exceeding 200 cycles per minute and preferably within the range 30 to 100 cycles per minute. The ratio of the capacitors 10 to 12 may be varied by switching additional capacitors across one of them. Specification 700,170 is referred to.