Patent GB-909472-A (GB)
Title: Improvements in letter sorting machines
Inventor: OSBORN HOWARD
IPC: B07C3/06
Filed: 1958-07-21
Abstract: 909,472. Sorting letters. THRISSELL ENGINEERING CO. Ltd. July 21, 1959 [July 21, 1958], No. 23327/58. Class 78 (1). In a letter sorting machine, letters are fed one at a time from a pile 103, Fig. 6, by means such as the suction device described in Specification 854,543, to a feed roller system, Fig. 1, which feeds them down to a roller conveyer 102, Fig. 6, running below the compartments. The first rollers of the system direct a letter into the shoot 3 where it rests on rotatable worms 4 behind a pair of discs 5. The worms and disc are driven from a one-revolution clutch 23, Fig. 4, and during successive revolutions of the clutch a letter is fed on to the worms, brought to the other side of the discs, and deposited on the movable support 8 where the address can be read through a hinged window 6 by an operator at the keyboard 100. The clutch may be as described in Specification 876,739. When the support 8 drops, the letter falls between  rollers 10 which feed it into a shoot 11 having a hinged window 12, feed-band 13 and a gate 14. When the latter is opened, the letter is fed by rollers 15 and a belt 16 mounted on a frame 153 pivoted at 54 to one of twin shoots 17A, 17B. The shoots have gates 19A, 19B, which when opened allow the letter to pass to feed rollers which forward it to the conveyer 102. The feeding devices described above are operated by cams 37-40 and a timing disc 36 fast on the shaft 22, Fig. 4, which is driven through the clutch 23. The clutch is driven through a continuously rotating shaft 24 running in synchronism with the conveyers and its output shaft 25 is coupled to the shaft 22 by 1: 2 chain reduction gearing 26. The cams 37, 38 jointly operate a lever 47 pivoted at 48 which carries rollers 49, 50 and is connected by links 51, 52 to an arm 53 integral with the frame 153. The first half revolution of the cams swings the frame 153 in one direction and the next half revolution in the opposite direction, thereby diverting consecutive letters into different shoots. The cam 39 engages a roller 55 on a pivoted lever 56, the lower end of which is connected by a link 58 to a lever 59 fixed to the left-hand member of the gate 14. The cam 40 is engaged by a roller 61 carried by a lever 62, an extension 63 of which operates the flap 8 through a link 64 and arm 65. The gates 19A, 19B are actuated by cams 75, 85 through similar linkages containing levers 72, 81, respectively, which normally are held from movement by stops 76. These stops can be moved to release the levers by the energization of electromagnets 77, 82. The windings of these electromagnets are in the anode leads of the thyratron tubes V4, V5, Fig. 3. The keyboard 100 has two sets of twelve keys 34, 35, one set for each hand of the operator, and in the example the operator has depressed the keys F, C. Since there is associated with each key an electronic tube in one of the banks of twelve tubes indicated by the rectangles marked " CODE STORE VI," one tube in each store has its grid fed and the joint output of the tubes charges the grid of tube V8 and current passes to energize a magnet coil to release a trip and permit clutch 23 to engage. The output shaft 25 carries cams 27-30, each of which engages a microswitch. As the shaft rotates, cam 27 eventually breaks the anode lead to each selected tube in STORE V1 while cam 28 has closed another switch to connect the cathodes of the tubes to the grids of similarly located tubes in the banks marked " CODE STORE V2." The tubes in these last-mentioned banks are connected to the TUBE MATRIX V3 which contains 144 two grid thyratrons. Since a left-hand key will feed one grid and the righthand key the second grid, only one tube of the matrix is made conducting, viz. the tube at the intersection of F line and C row. Cam 30 operates a microswitch to feed the grids of the selected tube from the cathodes of V2, and when each grid has been charged, the tube in V3 is ready to fire. Cam 31 on constant speed shaft 24 operates a micro-switch to cause anode feed to the selected V3 tube which then fires and a connection from its cathode charges one of the grids in each of the two grid tubes V4, V5. A coil in the anode lead of V3 causes pins to be set in timing drums, one of which is provided for each compartment, so as to cause a letter to be diverted to the selected compartment 144A. Similar drums operate the devices which divert letters to one or other of the five conveyers. After this the cam 29 operates a switch to break the anode circuits of the appropriate tubes in V2. Selection of which tube V4 or V5 is to fire is effected through tubes V6, V7 which charge the second grids of the tubes V4 and V5. Tubes V6 and V7 are controlled bv a disc 36 on the shaft 22 which has a permanent magnet 90 fixed on its rim. Two inductive coils are placed adjacent the periphery of the disc at 180 degrees apart, only one coil of which is influenced at each movement of the shaft. The induced current charges its associated grid in V6 or V7 and cam 32 on shaft 24 operates a switch which breaks the anode lead to the tubes in V3. Cam 33 actuates a micro-switch to break the anode feed to the tubes V4, V5. The current from the chosen tube energizes the corresponding magnets on the timing drums of the appropriate row and compartment and also determines the instant of energization of a gate solenoid and opening of a gate so that the letter is discharged to the conveyer system in proper timed relation with the movement of the latter. Each timing drum 123 is fast on a shaft 120 which is supported in a long bush 121 fixed in a bearing 122. A number of pins 124 are slidably mounted in the drum at equal distances apart in a circle concentric with the shaft 120. Coil springs 125 prevent accidental displacement of the pins. The armature 127 of an electromagnet 126 is pivoted to a fixed bracket 129 and is bevelled at the end where it engages a pin. When current is cut off from the coil of the magnet, a spring 130 returns the armature to the position shown in broken lines in Fig. 8. Movement of the armature to operative position takes place at such time that it can be inserted between two adjacent pins. When a pin rides up the bevel on the armature, it eventually contacts one end 131 of a lever pivoted at 132, the other end 133 of which is connected by a rod 134 to a bell-crank lever 135. The latter is fixed to a rod 137 which actuates a diverter for the letter. After the pin has operated the diverter, it is returned to inoperative position by a cam 139. Specifications 716,231, 768,504 and 849,421 also are referred to.