Patent GB-1049634-A (GB)
Title: Multi-uniform and variable pitch escapement mechanism for typewriters
IPC: B41J19/58
Filed: 1964-01-01
Abstract: 1,049,634. Typewriters &c. ROYAL McBEE CORPORATION. Jan. 1, 1964 [Jan. 17, 1963], No. 101/64. Heading B6F. Varaible and differential letter-spacing; escapement mechanism.-An escapement mechanism for a typewriter can be set so that it operates according to the width of the character to be printed or can be set to give a number of different letter-space widths which are uniform for that particular font. The selection of the kind of letter-spacing required is controlled by a dial 67 having a cam 66 with different flats 71-74. This controls the movement of a lever 64, link 63 and a crank 51 having a stud 48 engaging a cam surface of a by-pass lever 57. The movement of lever 57 deflects push wires 46 (operated from the various character keys) out of engagement with the differential escapement mechanism and permanently sets the mechanism to give a uniform letter-spacing. With the mechanism set to give differential spacing the lever 64 is in the position shown in Fig. 1. When a push wire is now operated from a key one of the Y-levers 38, 39 is rocked clockwise, and a permutation slide 35 or 36 is moved upwardly to the right below a universally actuated cancelling lever 33. This lever depresses stops 12 on the escapement wheel 10. If no wire 46 is actuated, indicating that a two-unit character space is required, the contour of the end of lever 33 causes two stops 12 to be depressed. When a three-unit space is required slide 35 positions itself in front of a recess in the cancelling lever and three stops 12 are depressed, while if a four-unit space is required both slides. 35 and 36 are operated and four stops 12 are depressed. Accordingly after the character has been printed two, three or four units of rotation of the wheel 10 occur before it is stopped by stop 13. Driving mechanism; carriage return; tabulating.-The drive to the escapement wheel 10 is through a shaft 14, Fig. 2 (not shown), which has a lead screw to which a type-carriage 16-18 is coupled. Freely mounted about the end of the shaft 14 is a drive pulley 25 driven by a belt 28. The belt 28 also drives a second pulley 19 free on a stub shaft 20. Pulley 25 is clutched to a drive gear 26 by a spring 27 and pulley 19 to which is yieldably coupled a gear 23. Positive drive is given to the escapement shaft, which rotates amounts determined by the stops, by a continuous motor drive to the belt 28 and pulley 25. The spring 27 is uneffective to drive the gear 26 so no drive is imparted by the gear 26 to the shaft 14. The same direction of drive however does effect coupling between the pulley 19 and gear 23 which is in mesh with gear 26 so, since gear 26 is connected to shaft 14 the latter will turn clockwise (Fig. 1) to the extent permitted by the escapement mechanism. To effect carriage-return or tabulation a friction shoe 29, Fig. 3 (not shown), carried on an arm 30 is moved into engagement with the free end of spring 27 to couple the drive pulley to the gear 26 and hence the shaft 14. The drive transmitted by gear 26 to gear 23 will disengage the spring clutch 24.