GB549960A - - Google Patents

Abstract

549,960. Calculating machines: BALL, W., KEEN, G. P., and BRITISH ADDING & CALCULATING MACHINES, Ltd. March 11, 1941, No.3335. [Class 106 (i)] A key-controlled machine of the kind in which the keys are depressed against the action of resilient means, and particularly a calculating machine in which the keys are depressed to set up amounts before the machine operation is initiated, has each key in a column or group arranged to engage a resiliently - tensioned flexible member in such a manner as to flex the tension member when a key is depressed and thus provide a returning force for the key, means being provided for varying the tension of said flexible member whereby its action on all the keys in a column or group is simultaneously varied. The key shanks 24, guided by plates 31, 32, are forked at 34 to straddle a helical tension spring 26, one end of which is secured to a hooked pin 27 adjustably secured by nuts 30 to the usual locking plate 128, while the other end is secured to a bar 23 common to all the springs and carried by two lever arms 35, one of which extends through a slot in the casing and is arranged resiliently to engage locating niches and has a manipulating knob 39, movement of which adjusts the tension of all springs. Depression of a key pushes the locking plate rearwards against the tension of spring 26, until nose 36 snaps over the abutment 37 on the key shank to lock the key in depressed position. The helical spring may be replaced by a spring-tensioned flexible cable. The spring or cable may be attached to a fixed part of the machine instead of to the locking plate, which then has a separate spring. Specifications 288,672, [Class 106 (i)], 343,448, 540,283, 540,311, 540,312, 540,313, 540,314, 540,315, 540,316, 540,317, 540,318, 540,319 and 540,320 are referred to.