Patent GB-316808-A (GB)
Title: Improvements relating to carriage returning mechanism for typewriting machines
IPC: B41J11/24
Filed: 1928-09-26
Abstract: 316,808. Fairweather, W. C., (Underwood Elliott Fisher Co.). Sept. 26, 1928. Carriage-returning mechanism; carriage-retarding devices.-In a motor-driven mechanism, a clutch is operated to couple the carriage and motor, and the speed of the motor and carriage is controlled by means of a cam having adjustable frictional engagement with a motor-driven shaft. The clutch may comprise interlocking members, engagement being effected by the cam and disengagement by means of a coiled spring adapted on arrest of the carriage to impart a reverse movement to the motor. The motor switch may comprise a contact-arm operated by a spring which is tensioned and tripped by a carriage-returning key. For automatically arresting the carriage on competion of the return movement, a margin stop adjustable with respect to the carriage carries a pivoted lug engaging a movable frame connected to means for releasing the contact-arm, the lug being operated by the carriage and maintaining engagement with the frame in all positions of the margin stop. The carriage-returning gear shown in Figs. 1, 4, and 10 comprises a motor 15 connected by a resilient coupling 32 to a worm 24 engaging a worm-wheel 25 on a shaft 26 provided with a pinion 14 engaging a rack 13 on the carriage 10. The coupling consists of a spring 33 secured to sleeves 34 having end parts engaging flats 36 on the motor shaft 22 and worm shaft 23. The wormwheel is held in frictional engagement with a collar on the shaft 26 by means of a spring plate 56 adjustable by means of screws 57. The pinion 14 is loose on the shaft 26 and is formed with a clutch member 28 for engaging a clutch member 27 on the shaft. To engage the clutch members, the pinion is moved axially in opposition to a spring 49 by means of a lever 31 actuated by a cam 37 which is frictionally mounted on the shaft 23 and is provided with a roller 50 engaging a flange 30 on the pinion. The cam is arranged between friction-washers 39 which are clamped by an adjustable spring mounted in a cap 43. The rack is detachably supported on brackets 67, 68 secured to a cross-bar 66 and having fingers 71, 74 engaging slots 100, 102 in the rack. The rack abuts at the front on shoulders 103 and is retained by detachable clips 104, 106. A base-plate 18 supporting the motor and gearing as a unit is secured by screws 52 to a bracket 19 secured to the main frame 11, the motor being attached to a bracket 16 which is formed with a gear-housing 17 and is secured by screws 54 to the base-plate. A plate 51, Fig. 1, and a plate 53 having depending edges are arranged between the base-plate and bracket, the plate 51 being replaced by one of different thickness to adjust the height of the pinion 14. A switch supported by an angle plate 115, Figs. 1, 4, and 18, on the main frame comprises contacts 128, 129, a contact-arm 127 engaging the hooked end of a spring 131, and a slide 113 which engages the lever 112 of the carriage-returning key and carries a pawl 132 engaging a shoulder 134 on the contact-arm. The contact-arm is pivoted on a bracket 119 secured to the plate 115, the spring 131 being anchored in the bracket, and the slide being guided at the top by the bracket and at the bottom by a screw 123. The contact-arm is provided with insulated contacts 138, and the contacts 128, 129 are mounted on an insulated block 130 provided with terminals 145. A spring 136 on the slide normally holds the pawl in engagement with a shoulder 137 on the slide and prevents chattering of the contact arm. The motor terminals are connected to a plug 166 on the bracket 16 and to one of pair of contacts 169, the other being connected to the plug and both being connected to the terminals 145. To permit detachment of the base-plate 18, the contacts 169 consist - of separable upper and lower members 170, 173 mounted in blocks 167, 174 secured to the baseplate and bracket 19 respectively, the upper members comprising spring-pressed rings for engaging the lower members. On depression of the carriage-returning key, the slide 113 is raised and the pawl 132 retracts the contact-arm 127 and tensions the spring 131 and when the pawl rides over the shoulder 134 the spring throws the contact-arm into engagement with the contacts and the motor is started. To stop the motor when the carriage has been returned, the contact-arm is automatically released by means of a depressible link 159 connected to a rocking frame 158 actuated by the margin mechanism. For this purpose the adjustable margin stop 155, Fig. 4, is provided with a pivoted member 156 which engages the frame 158 and has a lug in the path of an abutment 157 on the carriage. To permit of further travel of the carriage, the member 156 is turned over to avoid the abutment 157 and the - carriage is thereby permitted to travel until the .end 160 of the margin-release lever 161 depresses the frame 158 by co-operating with a cam 162 thereon. Release of the contact-arm is effected whether or not the carriage-returning key is held. When the carriage-returning key is depressed, the motor is started in the above described manner, and the shafts 22, 23, 26 run freely until the cam 38 rocks the lever 31 and causes the pinion 14 to be clutched to the shaft 26, whereupon the cam is arrested by the lever and retards the shaft 23, thereby causing the spring 33 to be wound. Thereafter the shafts 23, 22, 26 run in unison and the pinion drives the rack, and when the lost-motion in the slots 100, 102 has been taken up the carriage is coupled to the rack and is returned, line-spacing machanism described below being operated during the lostmotion movement. The cam, being frictionally retarded, regulates the speed of the motor and the carriage during the return movement. The friction coupling 56 absorbs shock when the clutch is thrown in. At the end of the return movement the motor is out out and the spring 33 unwinds and reverses the shafts 22, 23, whereupon the cam returns to the normal position, shown in full lines in Fig. 1, and the spring 49 releases the pinion. Line-spacing mechanism.-The slide 91, Figs. 1 and 4, of the usual line-spacing mechanism is provided with a bracket 95 engaging an arm 87 on a shaft 82 provided with a sector 83 engaging a pinion 116 which engages teeth 101 on the front of the carriage-returning rack 13. The shaft and pinion are mounted on the bracket 68. The arm 87 is adjustable to regulate the spacing and is secured by a screw 90 and co-operating teeth on the hub 86 of the arm and a collar 84 on the shaft. The arm engages the bracket 95 in both the normal and shaft position of the plate. During the above-described lost-motion movement of the rack, the arm is rocked and the line-spacing slide is operated.