GB723225A - Improvements in speed-indicating apparatus - Google Patents

Abstract

723,225. Speedometers. BRIERLEY, J. B., and BROOKS, J. H. Oct. 22, 1952 [Oct. 23, 1951], No. 24677/51. Class 106 (3). A speed-indicating apparatus comprising a differential gear having two elements adapted to be rotated at constant and varying speeds respectively and a third element the movement of which represents the difference in the rotational speeds of the first two elements is characterized in that the output element of the differential gear is connected to the main spindle of a counter mechanism having two sets of numeral wheels, adapted to indicate respectively the amount " fast " or " slow," in terms of time, by which the varying-speed driving element has departed from a desired pre-set average speed. An electric motor 13 drives a gear-wheel 24, Fig. 1, through the gearing 15, 16, 18, 19, 23 at a constant speed determined by an escapement mechanism, Fig. 2 (not shown). The gear-wheel 24 is free on a shaft 25 and carries two intermeshing planet wheels 34, 35, Fig. 3, which mesh respectively with gears 36, 37. The gear 36 is fixed to the shaft 25 and is driven through the gear train 38 ... 42, Fig. 1, and a variable speed gear comprising a roller 66, two balls 69, Fig. 5, and a disc 65 driven from a shaft 43, Fig. 1, the speed of which is proportional to the vehicle speed. The output gear 37 of the differential is connected through a sprocket and chain and a dog clutch 56 to the input shaft 50 of a counter 47 having two sets of numeral wheels 48, 49. The arrangement is such that the numeral wheels 48, 49 respectively indicate by how many minutes the vehicle is " slow " or " fast " with respect to the desired average speed as pre-set by the variable speed gear, the balls 69 of which are carried by a block 67 adjustable radially of the disc 65 through manually controlled means comprising a knob 74, a screwed spindle 75 and an arm 76 of the block 67. The block 67 carries a pointer 77 which is set to the desired graduation on the scale 78. The mechanism is within a housing having a transparent cover 12. To zeroize the counter 47 the knob 52, Fig. 4, is depressed to open the dog clutch 56 through the bell-crank lever 53 and a plunger 54 and to bring a contrate wheel 57 into mesh with a pinion 58 on the spindle 50 and the knob 52 is then rotated.