Scale changeover system for multiple range measuring instruments - has twin scale plug-in cards and range switch interlock

摘要

The scale-changeover mechanism for multi-range measuring instruments consists of a number of plug-in scale cards (3) which may be inserted to provide dial figures corresponding to the range selected on the meter movement. Each card carries two graduated scales (4) (4') which are selected by inserting the card with either one of the two long edges uppermost so that the relevant figures appear behind the window (8) in the masking plate to the rear of the pointer. The range-change switch of the instrument incorporates a slider switch with a locking bar which engages longitudinal slots (6) cut into the edges of the scale card. This ensures that the switch can only be moved to the position corresponding to the meter range as indicated in the window.