Patent GB-346833-A (GB)
Title: Improvements in or relating to speed indicators and speed-ratio indicators
IPC: G01P3/40
Filed: 1930-01-18
Abstract: 346,833. Comparison speed indicators. HERONIMOS, A. J., 69, Eaton Rise, Ealing, London. Jan. 18, 1930, Nos. 1819 and 9287. [Class 106 (iii).] A stroboscopic indicator for any number of preselected speeds between two relatively rotatable members comprises indicating and analysing means operated respectively by the members, the indicating members being provided with a set of indications and analysers for each relative speed indicated. A cylindrical casing 1 closed at one end 2 by a cap in the centre of which is a socket 4 for a lamp bulb encloses an inner indicating drum 8 fast with a driving shaft 7 finding a bearing in the centre of the end 5 of the casing. Loose on the bearing of the shaft 7 is toothed wheel 14 in one with an analysing drum 13 and driven by a wheel 17 on a shaft 16 also finding a bearing in the end 5 of the casing, but eccentric to the shaft 7. The shaft 16 is connected through flexible shafting 19 to a shaft 21 which is in the same box as the speedometer driving shaft 22. The shaft 7 is connected by flexible shafting to a shaft 25 driven at the speed of the lay shaft of the gear box. The shafts 11, 19 are so arranged that the drums 8, 13 rotate in opposite directions. In the form shown the gear box has three speeds and the slots cut in the inner drum are arranged in three bands 33 spaced axially of the drum. The outer drum comprises the analysing shutter and has similarly three bands of slots. An electric light bulb 34 of the strip light type extends across all three bands of slots. The outer casing has a window 35. In a modification, two similarly driven discs are provided with rings of slots and a light source is arranged at the rear opposite a window in the casing. In another form, the cap 2 of the casing carries a constant speed motor to the shaft of which is secured a third drum which extends into the casing 13 and is rotated in the opposite direction. The drum 13 is provided with sets of slots for indicating speed ratios in addition to the speed gear ratios. For indicating when engine and clutch are rotating at the same speed the drum driven by the motor above is replaced by a drum driven at engine speed. Several arrangements of slots are described. The outer drum 13 is driven at the speed of the driven shaft of the gear box and the inner one at the speed of the lay shaft the ratio of the number of slots in the outer and inner drums being the same as the speed ratios between the lay shaft and driven shaft according to which set of gears is engaged. The slots, Fig. 6, are all of the same length axially but are inclined so that in two co-operating sets of slots, the ratio of the cotangents of the angle which the slots make to their direction of movement is equal to the ratio of the speeds of the members which is required to be indicated. To reduce flicker in each set of slots, the length is arranged so that at all times a part of at least one slot is opposite a fixed datum line. In another form the slots are V-shaped with the apexes arranged oppositely, a hole at the apex in one drum co-operating with a stencilled numeral in the other. In other forms inclined legends or numerals may be stencilled in one drum, or numerals and slots may be arranged alternately or different colour fabrics stretched across the slots. In a final form which is a modification of the disc form, one disc is dispensed with and replaced by commutators 78, 79, 80 secured to the shaft 16, each commutator is connected in circuit with a light source 81 opposite one of a set of apertures in the disc. The three light sources are disposed apart and a window &c. 2 is arranged in the cap 2 opposite each. The disc 36 will have three concentric sets of slots corresponding to the gear ratios.