Patent GB-190011404-A (GB)
Title: Improvements in Typewriting Machines.
Inventor: BURRIDGE LEE SPEAR
Filed: 1900-06-23
Granted: 1901-03-16
Abstract: 11,404. Burridge, L. S. June 23. Type - writers. - The type-bars 5 are pivoted to a curved rod 9, the plane of which is vertical, so that all the bars strike radially inwards to the impression point. Comb-plates 10,11, curved cylindrically, guide the short and long arms of the type - bars respectively. Springs 12 connect the lugs 13 to a curved rod 14 fixed in a plane parallel to that of the rod 9. In the normal or rest position of the type-bars, shown in Fig. 2, the spring 12 partly counterbalances the weight of the bar and tends to lift it. As the bar swings towards the platen 47, however, the lug 13 crosses the line joining the bars 9 and 14, and the spring then tends to check the forward movement of the type-bar and assists in returning it to the cushioning-support 15. The type-bars which strike in a sideways fashion on the platen, i.e., which move in planes inclined to the vertical, require less counterbalancing by the springs 12 than the bar shown in Fig. 2. To allow for this the rod 14 is formed with a curve of greater radius than that of the rod 9, so that springs attached near its ends are in the normal position nearly in line with the rod 9, and exert little counterbalancing force on the type-bar. The outer ends of the type-bars are formed with troughs 16, Fig. 11, in which the type-blocks are cemented by shellac &c. It is however, desirable to vulcanize the rubber directly in the type-trough 16, and to ensure perfect adhesion between the rubber and metal the trough is preferably made of copper or a copper alloy. The key levers 3 are of bell-crank type, and are pivoted on three rods 7. The arms 3<a> are so proportioned to the arms 3 that the same pressure is required to operate all the keys. The paper carriage 6 has at the rear a guide-rod 54 sliding in a long sleeve 55 carried by the shifting-frame 56. The carriage feed-rack 18 bears against an antifriction roller 76 on the shifting-frame, and engages with a pinion 19 of sufficient length to permit of the vertical shift of the carriage when writing upper-case characters. On the shaft of the pinion 19 is mounted the escapement-wheel 22, shown in sectional plan in Fig. 6. Pivoted at 24<a> to a fixed vertical plate 23 is an arm 24, provided with a downward extension 27 and terminating in a short laterally-extended head 25, against which all the type-bars must strike as they enter the flared slot in the guide-plate 35, which centres them at the impression point. The head 25 thus constitutes a universal bar for the type-levers. The spring 26 normally holds the head 25 forward, and the link 28 holds up the spacing-key 29 against the stops 30. The arm 24 carries a spring plate 36, which constitutes an escapement-pawl. The escapement-wheel 22 normally holds the spring plate up against the rigid part of the arm, but when the head 25 is struck by the advancing type-bar, the spring plate drops below the tooth of the wheel, which then engages with the rigid part of the arm. The plate 36 springs outwards against the stop 37. During the return of the arm 24, the tooth escapes through a slot in the rigid part of the arm, and the succeeding tooth brings back the spring plate to the position shown in Fig. 6. The escapement can be released and the carriage freed by sliding aside the spring- controlled stop 30, so that the spring 26 can pull the arm 27 further to the rear and lift the spring plate 36 above the escapement-wheel. The inking-mechanism, shown in plan in Fig. 7, consists of a pad 39 of felt &c. supported by a flexible arm 40 of sheet rubber. The pad swings aside, as indicated by dotted lines, when the type strikes it. The plate 41 which carries the inking- pad, is mounted on a supporting-bracket 43, so as to be easily detachable. The carriage is provided with a guide-plate 51 for the paper, and a spring wire guide running from end to end of the platen. To the shifting-frame 56 is adjustably secured a stop 59, which co-operates with a stud on the carriage to determine the width of the margin. The shifting-frame also supports the alarm bell, the spring drum which drives the carriage, and an arm carrying an antifriction roller which supports the carriage in its extreme left-hand position. The shifting-frame is operated by a key which lifts it vertically. For the springs 12 may be substituted fork-shaped springs between the prongs of which move pins carried by the links or key levers 3 ; or the key levers may be sufficiently large and heavy nearly to lift the type-bars by their own weight, check springs being arranged to act on them after they have been partly depressed.