Patent GB-350426-A (GB)
Title: Improvements in and relating to automatic stops or braking devices for gramophones and the like
IPC: G11B17/02
Filed: 1930-02-07
Abstract: 350,426. Gramophones. ORFEN, F. J., BUTLER, W., and GARRARD ENGINEERING & MANUFACTURING CO., Ltd., Newcastle Street, Swindon. Feb. 7, 1930, Nos. 4214, 12760, and 19137. [Class 40 (ii).] Relates to automatic braking devices for gramophones and the like, wherein a displaceable member is moved towards the centre of the turntable by the action of the tone-arm as the stylus tracks the 'record and is intermittently set back a corresponding amount by a rotating striker on or associated with the turntable, such intermittent action continuing until the stylus is given an increased movement at the end of the record when the member is given a displacement to effect the application of a brake. According to the invention, the displaceable member acts as a trigger which, when the increased inward movement of the stylus occurs, is adapted to release a spring-actuated brake which is normally held out of operation. The trigger may be adapted to disengage a detent or sear which normally holds the brake out of engagement. In the construction shown in Fig. 1, a trigger 9 is adapted to slide on a lever 4 and is held in its outermost position by a spring 13. The lever 4 is pivoted on a stud 2 and is in frictional engagement with a lever 1 which has a post 3 adapted to be engaged by the tone-arm. An upturned end 10 of the trigger 9 is engaged by one end of a detent 25, the other end of which normally engages a notch 22 in a pivoted threearmed brake lever 20 so as to prevent a brake 23 from engaging the turntable rim under the action of a spring 24. During playing of a record a cam face 15 on the end of the trigger 9 is caused to enter the path of a striker 16 on the turntable boss 17 and to be intermittently replaced thereby. When the lever 4 and trigger 9 receive an increased inward movement a nose-piece 14 on the trigger 9 is engaged by the striker 16 and the trigger 9 is moved longitudinally so as to actuate the brake. A stop 5 on the lever 1 may operate upon a cam surface 25a on the lever 25 so that manual displacement of the tone-arm may, on operation of a knob 7 on the lever 1, release the brake independently of the striker 16. An arm 21 on the brake lever is engageable by the lever 1 for setting purposes. In another construction shown in Figs. 3 and 5, a lever 1, which extends slightly upwardly and has a post at its end for engagement with the tone-arm, is mounted together with a setting plate 33 on a sleeve 31 rotatable on a pin 30. A lever 35 is rotatably mounted on the sleeve 31 and the displacements of the tone-arm lever 1 and plate 33 are communicated to the lever 35 by a friction device comprising washers 34, 36 and a spring 37. The striker at the end of the lever 35 consists of an adjustable screw 39 arranged to lie in the path of a projection on the turntable spindle 19, such projection consisting of a pad 16 at the end of a coiled spring 40 on the spindle. A shoulder 22 on the side of the lever 35 or on the side of a slot in the lever is normally engaged by a detent 26 in the form of a bell-crank lever controlled by a spring 24. Coaxially mounted with the detent is a brake member having a brake pad 23 and adapted to be mounted upon the detent in either of two alternative positions according to the size of the turntable by means of set-screws 43. During playing of a record, the screw 39 on the lever 35 is moved into the path of the striker 16 which intermittently replaces it until the screw receives a greater displacement and the detent is unseated from the shoulder 22 so as to effect actuation of the brake 23. A cam surface 41 adjacent the shoulder 22 of the lever 35 serves for resetting the detent and also to push the lever 35 so that the screw 39 is out of the path of the striker 16. The trigger 35 may be adapted to actuate a separate lever to release a spring-operated brake. The lever 1 is formed as a blade spring or with a spring hinge mounting so that when applied to portable gramophones the pressure of the lid may displace it inwardly. The striking arrangement comprising the adjustable screw 39 and coiled spring 40, and the adjustable method of mounting the brake pad 23, may be applied to the device shown in Fig. 1. One of the provisional Specifications also describes an arrangement wherein the intermittently-moving lever is loosely mounted on a vertical sleeve carrying a member engaged by the tone-arm and is adapted to move with the tonearm by frictional engagement between the lever and a plate on the sleeve. The intermittent return movement of the lever is effected by a flat spring extension on the lever engaging frictionally a pin on the turntable, such movement preventing, during playing of a record, the disengagement of a sear on a bell-crank brake lever from a detent formed in a slot in the lever. When the increased inward movement occurs, this disengagement occurs and the brake is applied. The member engaged by the tone-arm is adjustably mounted on the vertical sleeve by means of a serrated surface and clamping screw, and the plate on the sleeve has a curved cam surface and also a stop for engaging respectively the brake-lever sear and a leaf spring on the lever for resetting purpose.