Dial indicator esp. for vehicle speedometer - uses thirty degree divisions with 10 corresponding to 1 o'clock to facilitate reading of dial

摘要

The motor vehicle speedometer uses either a needle or an opaque disc with a cut-out to indicate speed on a face marked in 30 degree divisions corresponding in layout to a 12 hour clock face layout, with 10mph (or kmph) corresponding to 1 o'clock, 20 mph (or kmph) corresponding to 2 o'clock, continuing to 120 mph (or kmph) corresponding to 12 o'clock. To facilitate reading sectors drawn from the centre of the circular face are filled in differing colours or different degrees of shading. To extend the range above 120 mph (or kmph) a fan segment is drawn over the face and an opaque disc with a notch or segment cut-out used as the indicator. The fan segment is drawn by the pointer disc so the 10 marking is covered by a 130 marking, and so on, the fan returning to its folded form as the speed falls below 120.