Patent GB-1453584-A (GB)
Title: Journey plotter
IPC: G01P1/12
Filed: 1975-03-06
Abstract: 1453584 Tachographs; speedometers MOTO METER GmbH 6 March 1975 [11 March 1974] 9373/75 Headings G1J and G1K A vehicle tachograph has a casing 1 with a base wall 4 and a pivotally mounted front lid 2, a rotatable diagram disc 3 between the lid and the front face of the base wall 4, and a number of measuring and/or recording mechanisms A, B, C mounted in the casing 1 to record data on the diagram disc 3, each mechanism being incorporated in an individually demountable assembly arranged on the rear of the base wall 4 to be accessible from that side alone. The casing 1 also contains an odometer unit D, the lid 2 being pivotally connected to the base-plate 111 of the odometer unit D by two hinges 113. The lid 2 carries a speedometer scale and pointer and a clock (9), which also drives the diagram disc (3), Fig. 1 (not shown), and is lockable in its closed position by a key 13. A cover 141 covers the rear part of the lid. A speed measuring unit A, Figs. 4, 6, 7, has a base-plate 55 secured by screws 57 to pillars 56 on the wall 4. An input shaft 16 rotates a magnet 17 within an eddy current cup 21 on a shaft 24 to rotate the latter against a spiral return spring 25 by an amount dependent on the shaft 16 speed, and hence vehicle speed. The cup 21 has a temperature compensating member 22 mounted internally and a magnetic short-circuit ring 23 mounted externally. A stationary magnetic shunt plate 29 for fine adjustment of speed sensitivity is mounted adjacent the magnet 17, being adjustably tiltable about a pin 32 by a screw 31. The outer end of spring 25 is secured to a member 28, Fig. 4, rotatably adjustable about the shaft 16 by a tool 61 having a pinion 59 to engage gear teeth 58 on the member 28. Locking screws 62 engage slots 63. Shaft 24 is connected by gears 26, 36, 38 to a rack 39 of a carriage 41 slidable on a bar 44 and carrying a stylus 45 which projects through a slot 6 in the wall 4 to record speed on the diagram disc 3. Screws 46, 47 provide adjustable limits for the carriage 41. The gear 38 also moves a balance carriage 42 slidable on a bar 43. A gear 49 integral with gears 36, 38 meshes a gear 51 on a connecting member 52 which engages a coupling element (50) on the rear end of a shaft (54) carrying the speedometer pointer (8) Fig. 8 (not shown). A distance plotter B, Figs. 4, 9, has a base-plate 64 to which is pivoted at 78 an arm 79 carrying a stylus 81. A pin 82 on the arm 79 engages an eccentric cam 77 rotated in accordance with distance travelled by the vehicle so that the stylus 81 produces a zig-zag trace on the diagram disc 3. The cam 76 is driven from the shaft 16 via a worm 18, a worm-wheel 20, ratchetting means (not shown), a shaft 33, worm 34, worm-wheel 66, a shaft 67, worm 72, worm-wheel 73, a shaft 74, worm 75, and worm-wheel 76. Worm-wheel 76 and cam 77 rotate on a shaft 84 carried by a sector plate 86 pivoted at 85 to the base-plate 64 and adjustable by the tool 61, to adjust the track of stylus 81. A driving time plotter C, Figs. 4, 12, has a baseplate 91 to which is pivoted at 97 an arm 96 carrying a stylus 98. A link 95 connects the arm 96 to a crank-pin on a gear 94 mounted on an adjustable sector plate 101 and meshing a gear 93 having a slotted arm 125 engaged by a crank 124 on a shaft 119, Fig. 13, carrying a selector lever 7 at the front of the instrument. A spring detent 121, 122 determines rest positions of the lever 7 corresponding to track positions of the stylus 98 for recording various driver duties, e.g. driving, resting, loading. The stylus 98 is oscillated by a cam 35 on the shaft 33 when the vehicle is moving, to produce a bar chart. Base-plate 91 carries electrical terminals 103 connected by a cable 12 to the clock mechanism in the lid. The odometer D, Fig. 13, has a base-plate 111 and is driven from the shaft 67, Fig. 9, via gears (68, 69) a coupling 71, and a shaft 118. Its reading is visible through a window 14. The base-plate 111 also carries the driving time selector lever 7. Security of the mechanism is provided by cap 5 covering the rear of the tachograph and secured to the base-plate 55 by screws 132 (133, 134) one of which is secured by a seal 150. This cap 5 must be removed for adjustment or replacement of any of the mechanisms A-D.