Patent GB-225285-A (GB)
Title: Improvements in and relating to brake controlling mechanism of the set stop type forthe motors of gramophones and the like
IPC: G11B17/02
Filed: 1923-08-28
Abstract: 225,285. Slade, H. V., and Garrard Engineering & Manufacturing Co., Ltd. Aug. 28, 1923. Starting and stopping.-Relates to automatic brakes for gramophones and the like, of the kind in which when the brake is set by moving it to enable a detent to hold the brake in the " off " position against the action of a spring, a trip lever is angularly displaced, this lever being moved back by engagement of the tone-arm or the like therewith at the end of a record so as to release the brake. According to the invention, provision is made whereby the mechanism can be so adjusted that the angular displacement of the trip-lever necessary to effect the application of the brake is either less than, greater than, or equal to the displacement incidental to the setting operation, as may be necessary, thus compensating for slackness or imperfection in the construction of the mechanism. A spring-pressed lever j, carrying a block j<1> for engagement with the turntable m, is pivoted at k. One end of the lever has therein a slot j<4>, having a shoulder j<3> which forms a detent adapted to coact with a stop h<1> on a lever h. This lever, which also carries an adjustable stop h<2>, is linked through a member f to a lever d, pivoted at c and frictionally connected to a triplever b which is mounted on the same pivot. The stop h<2> is adapted to bear against the part n<1> of a starting-lever n when the mechanism is in the position shown in Fig. 4, the machine being then at rest. The adjustment of the stop h<2>, which is dependent on the amount of slackness for which compensation is necessary, determines the initial position of the stop h' relatively to the edge j<6> of the slot j<4>. In operation, the sound-box is first placed at the finishing point on the record, and the lever b is shifted so as to bear against the tone-arm or like part. The position of the mechanism at this stage is shown in Fig. 4. The soundbox is then located at the starting-point, and the lever n is moved from the position shown in Fig. 4 to that of Fig. 5. The lever n bears against a lug j<2> on the brake-lever j, which is thus moved so as to free the turntable, and in this movement an inclined end j<5> of the slot j<4> pushes the stop h<1> down so that it engages behind the detent shoulder j<3> and holds the brake " off." With this movement, the trip-lever b is displaced from the position f to the position z<2>. Assuming that the stop h<2> has been protruded as shown, when the end of the record is reached the lever b will have been displaced by the tone-arm through a smaller angle than the original displacement occurring during setting, the movement being just sufficient to disengage the stop h<1> from the shoulder j<3>, whereupon the brake is applied. If it is necessary that the angular displacement of the lever b during disengagement of the brake should be greater than the displacement during the setting operation, the edge j<6> of the stop j<4> must be cut away as shown in Fig. 8, the stop h<2> being then set so as to allow the fixed stop h<1> initially to bear against the recessed edge. Fig. 7 shows the frictional connection between the parts b, d, comprising a spring plate o engaging a screw o<1>, which is adjustable to vary the friction.