GB618329A - Average speed indicator for road vehicles - Google Patents

Abstract

618,329. Average-speed indicators. MORRIS MOTORS, Ltd., and LANDSTAD, H. F. Oct. 18, 1946, No. 30992. [Class 106 (iii)] An instrument for continuously indicating the average speed of a road vehicle comprises mileage and time-indicating mechanisms actuating angularly movable co-operating indicators arranged to intersect over a set of average speed curves correlated with mileage and time scales associated with the respective indicators, and is characterized in that the mileageindicating mechanism includes a planet carrier (25), the planet gear of which meshes simultaneously with a concentric pair of spur gears, one of which is immovable and has n teeth, and the other of which is rotatable by the planet gear and has n-1 teeth. A pointer 6, driven by a normal clockwork mechanism 9 through a gear-wheel 10 and sector 12, indicates running time on a scale 3. The other pointer 7 is driven by a high-reduction gear from the road wheels and indicates mileage on a scale 2. Curves 5 form an average speed scale for reading off the point of intersection 8 of the two pointers 6 and 7. The drive from the road wheels is transmitted through gears 17 and 18 to a worm 22 driving a worm-wheel 23 integral with a planet gear carrier 25. The planet gear 26 rolls round a fixed gear 27 and a gear 28 having one tooth less than the latter. Thus, the gear 28 rotates slowly, turning a snail cam 35 which rocks a pawl lever 36 gradually to the left until the fall in the cam allows a spring 39 to bring it quickly back. The pawl 40 rotates a ratchet - wheel 41 which is geared. to the pointer. Slipping clutches (45a for pointer 7 and 11 for pointer 6) allow for zeroizing the pointers manually, extensions 45 and 14 being provided for this purpose. A knob 46 is provided for winding the clock mechanism.