GB619777A - Improvements in or relating to variable resistance devices and to electrical controlsystems incorporating such devices - Google Patents

Abstract

619,777. Linkwork. NICHOLS, W. T. Sept. 3, 1946, No. 26452. [Class 80 (iii)] .[Also in Groups XXXVI and XXXVII] In the variable resistance device shown, Fig. 1, movement in either direction of control lever 8 produces unidirectional movement of lever arm 1 so that contact 2 carried by arm 1 describes an arcuate path over resistance 15. The bell crank lever 1, 3 and co-operating pivoted lever 4 are connected together by a pin and slot at 5 and carry respectively rollers 6, 7. For clockwise movement of lever 8, cam lever 17 pivots counterclockwise so that roller 7 is freed from cam face 10 by pin 5 acting on lever 4 and roller 6 rotated by cam face 9. For counter-clockwise movement of lever 8 cam lever 17 pivots clockwise, roller 6 disengages and roller 7 is rotated by cam face 10. In the first case roller 6 produces movement of arm 1 and thus contact 2 and in the second case roller 7 produces the movement both in the same direction. Different control mechanisms for producing rectilinear movement of contact 2 may be utilized for example a rack and pinion, Fig. 2 (not shown), a crank and connecting rod, Fig. 4 (not shown), or Fig. 3 (not shown) an arrangement in which either one of a pair of rollers on a single pivoted member produces the required unidirectional movement.