GB1375110A - - Google Patents

Abstract

1375110 Retractive switches; switches retained set CUTLER-HAMMER INTERNATIONAL FINANCE Inc 8 Dec 1972 [8 Dec 1971] 56897/72 Heading H1N A selective plural-position trigger switch for speed control of electric motors for portable tools includes an insulating base 2 accommodating the fixed conacts 48, 50, 52 and a slidabletrigger 8 which houses a spring-biased movable contact 54 and which has arrangements at the finger-engaging end 8a for mounting a speed selection knob 24 with its integral shaft 27, position detent grooves 36 spaced 90 degrees apart and eccentric drive pin 38, together with a recess for the trigger return spring 12. A central cavity 30, Fig. 5, of the trigger member houses a detent spring 32 for engagement with diametrically opposite pairs of the grooves 36 and a stop block 42 which is coupled to the knob by engagement of the pin 38 within an elongated hole 40. The stop block is guided by a runner 58 within a slot 60 for slidable movement in conjunction with the trigger and it can also be moved up and down within the cavity by turning the knob 24 through 90 degrees from the 12 o'clock to the 9 or 3 o'clock positions so that, for example, in the selected "L" position of Fig. 3, a shoulder 44 abuts edge 46 of the metal frame 10 when the trigger is depressed to a first position which causes contacts 48, 50 to be bridged. In the selected "H" position (Fig. 4, not shown), the shoulder 44 can slide beneath the frame edge when the trigger is depressed to a second position, whereupon switch contacts 48, 52 are bridged, and further movement of the trigger is limited by stops 14 abutting against the ends of apertures 16 in the frame 10. Following depression of the trigger the switch can be held in either of its selected "ON" positions by depression of a spring-loaded lock pin 20 (Fig. 1, not shown), which has a flanged end for engagement with one of the recessed catches HS, LS formed on the side of the stop block 42 and the trigger can be released for return to the "OFF" position by spring 12 by a slight further depression in order to free the flanged end. The switch is primarily intended to have a two-position selection knob for the control of a two-speed motor (diagram, Fig. 6, not shown), but the knob can also have three positions arranged in conjunction with a threeposition stop block having two abutment shoulders which would be effective in the 12 o'clock, 9 or 3 o'clock, and 6 o'clock positions of the eccentric pin. Figs. 7 and 8, not shown, refer to an alternative embodiment of trigger which has an upstanding finger-engaging portion with the return spring mounted above the frame. The frame member may be made of plastics material and may be a snap-fit on the body.