GB492548A - Improvements in or relating to adjusting devices for rotatable members, for example,in wireless apparatus - Google Patents

Abstract

492,548. Adjusting wireless apparatus ; friction gearing. PLESSEY CO., Ltd., MORRISON, P. H., and PACKMAN, P. J. June 25, 1937, No. 17787. [Class 37] Also in Group XXIV] In an adjusting device for rotatable shafts, for example, the tuning shaft of a radio receiver, a hollow shaft 12 screwed at 13 to the tuning condenser shaft 10 is rigid with a cup member 14 secured to a knob 15 which is manually rotated to effect approximate tuning directly. For fine tuning, a thumb wheel 20 projecting through a slot in the knob 15 is rotated. The thumb wheel is keyed to a spindle 21 rotatably mounted in the cup member 14, and drives a shaft 32 through reduction gearing comprising flanges 24, 25 pressed by a spring 27 frictionally to engage and rotate the edge of a cup member 31 rigid with the shaft 32. The shaft 32 drives the condenser shaft 10 through epicyclic reduction gearing comprising balls 34 mounted in a cage formed by holes in the hollow shaft 12 and engaging the reduced end 33 of shaft 32 and conical rings 36 resiliently held together and anchored at 37, 38. A tuning pointer 39 is fixed to the shaft 12 and moves between a scale 41 and window 42 carried bv an escutcheon 40. The pointer is arranged parallel to the axis of the thumb wheel 20, and, during fine tuning, moves in the same direction as that of the projecting portion of the thumb wheel. The pointer may, alternatively, be driven rectilinearly by a cord from the shaft 12 and co-operate with a rectangular dial.