speedometer, in particular for motor - witness

摘要

829,901. Speedometer indicating mechanisms. SOC. PER AZIONI FRATELLI BORLETTI. March 1, 1956 [May 25, 1955; Oct. 28, 1955], No. 6524/56. Class 106 (4). The speed responsive element of a tachometer moves a ribbon 47 stretched between two drums 45, 46 along a scale, the ribbon having an indicating mark formed, e.g., by a coloured portion 12 and being maintained under tension so as to show through an elongated window parallel to the scale, the ribbon 12 being open-ended and a closed loop being completed through pulleys 41, 43. In one form a magnet 38 driven by the shaft 49 is surrounded by a cap 37 fixed to a drum 39 over which passes a wire 40 connected to the pulleys 41, 43 on shafts 42, 44 carrying drums 45, 46 to which the ends of the ribbon are fixed, the wire and the ribbon being wound in opposite directions. The pulley 43 and drum 46 are loose on the shaft 44 and have pins acted on by a spring 48 to maintain tension in both the wire and the ribbon. A spring 50 opposes the turning of the cap 37 in proportion to the speed of the vehicle &c. The wire and ribbon may be fixed between idler pulleys tensioned by a spring and pulleys or drums forming part of the cap 37 of the speed-responsive element. In a further modification the wire is dispensed with and the ribbon passes from the cap of the magnet over two idler pulleys to a drum coaxial with the magnet cap and tensioned by a spiral spring.