GB1225752A - - Google Patents

Abstract

1,225,752. Time switches. SANGAMO WESTON Ltd. 8 April, 1968[9Jan., 1967], No. 1064/87. Heading H1N. A time switch with a 24-hour dial carrying ON and OFF tappets has omit control mechanism providing each of the facilities of allowing independent preselection of omission of, firstly, at least one switch closure operation, secondly, at least one switch opening operation and thirdly at least one closure and one opening operation for each of seven successive day periods. As shown, switch contacts and associated terminals are carried by a first section of a time switch, while a synchronous motor, gear train, timing dial carrying adjustable switch-operating tappets, and switch control means operated by the tappets are carried on a second section which is readily attachable to and detachable from said first section. The first section 10 comprises a box-like base member 11 having secured therein a mounting plate 12 carrying switch contacts (not shown), terminals 16, and a splined shaft 13 which when stepped causes a cam to open and close the contacts alternately. The second section 17 comprises a mounting plate 18 journalling a shaft 20, driven via worm 19 by a motor (not shown), and coupled (by a friction clutch to permit time setting) to a 24- hour timing dial assembly 21 carrying ON and OFF tappets, such as 22, and "omit" pegs (not visible). The tappets 22 are adjustable around the periphery of the timing dial and act on respective ON and OFF pawls (such as 43, Fig. 5, not shown) to step a switch operating spindle 15 by engagement with respective ratchets 40c and 40a integral therewith. When assembled, the splined shaft 13 enters a corresponding socket in the end of spindle 15, to be driven thereby. On the reverse side of dial assembly 21 two omit pegs are inserted in selected slots (31, Figs, 2 and 3, not shown) and cooperate with a star wheel (68, Figs. 7 and 8, not shown) to rotate discs 51, 52, 53 once in seven days by twelve-hourly steps. Fourteen omit tappets 56 corresponding to the twelve-hour periods are carried by the disc 52 and each has two axially spaced lugs and can be adjusted such that either or neither lug engages a portion (87, Fig. 6, not shown) of a lever 70 or 71 to render the associated ON or OFF pawl inoperative during the appropriate twelve-hour period. A manual override control knob 76 may be turned anti-clockwise to cause a pawl 80 to step ratchet 40b and change the condition of the switch contacts or may be turned clockwise to act on the levers rendering both the ON and OFF pawls inoperative so that the timed switching does not function. A spring retracts knob 76 from the anticlockwise position and a releasable lock holds it when turned clockwise. A transparent cover 92 seats on a gasket around the edge of base 11 and is releasably secured by turn keys 91.