Patent GB-260581-A (GB)
Abstract: 260,581. National Cash Register Co., (Assignees of Robertson, W. H.). Oct. 30. 1925, [Convention date]. Calculating-apparatus and cash registers, operating by motors.-The main operating shaft of the machine is driven by the motor through resilient means and a driving connection which is automatically disabled when the operating shaft is suddenly stopped as by obstruction in the machine; the motor is at the same time switched off. The counter-clockwise rocking of the release shaft 30 releases a spring-controlled lever 33 to remove its end 36 from blocking discs 38, 41, 42. The disc 41 is fixed to a clutch member 46 and between the disc and disc 38 is a spring 44 tending to rotate the latter counterclockwise (Fig. 3). Thus the freeing of disc 38 permits it to turn and through a cam surface 47 rock a lever 49 clockwise so as through a stud 51 to draw an arm 52, Fig. 7, downwardly to depress spring blades 76 upon contacts 79 to close circuit for the motor. The arm 52 does not bear directly upon the blades but upon a flange 56 forming part of a slide 57 mounted upon the arm and carrying a pawl 65 pivoted to the slide at 65<1> and provided with a cam slot 66 co-operating with a pin 67 mounted on the arm 52. The starting of the motor drives a worm-wheel 87 secured to a casing 90 enclosing a loose disc 91 carrying a pair of pawls 95. The casing is connected with the disc 91 by a coiled spring 92 one end of which is engaged with the casing periphery and the other is attached to the hub of the disc 91. Secured to the. shaft 89, geared through a friction clutch, including member 46 and rollers on disc 42, with the operating-shaft of the machine, is a disc 96 notched to be engaged by the pawls 95, and loose upon its hub is a. disc 105 provided with cam slots 106 cooperating with pins 107 on the pawls. Normally the disc 105 is locked to the casing 90 by the inter-engagement of peripheral notches on both, but by drawing out the disc and rotating it clockwise the disc 91 may be rotated to tension the spring 92 to the desired extent and then be returned into locking engagement with the casing. With the motor in operation therefore the pawls are driven by the casing through the spring 92 and they in turn rotate, the disc 96 and shaft 89. If the operating shaft meets with an untoward obstruction and disc 96 is thereby stopped the spring 92 permits continued movement of the casing and therefore of disc 105 and this causes, through cam edges 120 and pins 67, an outward displacement of the pawls 95 so as to break the driving connection. The further rotation of the disc 91 carrying the pawls results in the pins 107 engaging and rocking clockwise an arm 121 thereby drawing pawl 65 and with it slide 57 to the right to remove flange 56 from beneath the arm 52 and permit the blades 76 to rise out of contact and thus break the motor circuit. In this movement of the slide 57 the cam slot 66 causes the pawl 65 to rock out of engagement with the arm 121 at the completion of the movement. To indicate, the part of the cycle wherein the obstruction occurs the main shaft 116 is fitted with a graduated disc 117 read against a fixed pointer 118.