Patent GB-820819-A (GB)
Title: Yarn carrier drive mechanism for straight bar knitting machines
IPC: D04B15/64
Filed: 1957-03-25
Abstract: 820,819. Knitting-machines. COBERT, A. J. March 25, 1957, No. 9649/57. Class 74 (2). In the device to a plurality of yarn carrier supporting rods in a straight bar machine, there are: a member positively reciprocated by the coutier mechanism; an electromagnetic clutch and automatic engaging and releasing means therefor, between the said member and a slide bar; between said slide bar and respective of said rods, electromagnetic clutching and braking devices, and means controlling them to render selected rods operative and inoperative; adjustable stop devices for limiting the traverse of the slide bar in each direction; and end stops for controlling the traverse of each of said rods. Yarn carriers 96-102 are driven, each by an individual rack and pinion such as 148, 146, through an individual electromagnetic clutch such as 138, 136 driven by an individual pinion such as 142, in turn driven by a common rack 130 borne on a main carrier slide bar 108, the rack 130 being reciprocated through gearing and a main electromagnetic clutch 110, 111, which is, in turn, driven through a pinion 114 and a rack 116 borne on a driving bar 106 reciprocated by the coutier lever 84. Each individual drive also embodies an electromagnetic brake, such as 150. Certain of the carriers, particularly short course carriers, can be similarly controlled and driven at half speed, through a similar system of racks, pinions and electromagnetic clutches and brakes, by a driving bar 154 reciprocated from an intermediate point in the coutier lever, at half the speed of the bar 106. The traverse of the carrier rods is determined by stop blocks 208, 210 adjustable on lead screws. Any slip necessary between the coutier drive and the individual carrier rods is provided by controlling the voltage across the main clutch. A retarding and shock-absorbing arrangement for the bar 108 comprises stops 242, 248 on the bar, the appropriate one of which, as the bar and the active carrier rod approach the stop position, engages the vertical arm of the appropriate one of bell-cranks 234, 236 carried on the halfspeed bar 154. As the stop position is more nearly approached, the horizontal arm of the bell-crank rides over the appropriate one of cams 250, 254 mounted on the stop blocks, so that the bell-crank is rotated to increase the retardation. In order that the bar 108 may be able to move to the limit of its travel, as in bringing a new carrier rod into action, this retarding and shock-absorbing mechanism may be rendered inoperative by means of a bar 264 carried on arms on a rock-shaft and above to slide the stops 242, 248 upwardly to an inoperative position. The various operations of the machine are controlled electrically. To this end, there is provided a pattern chain riding over a drum stepped round in time with the rotation of the main cam-shaft. Buttons on the pattern chain cause the operation of switches which control solenoids and the clutches and brakes. Thus, one solenoid actuates the bar 264, to render the shockabsorbing mechanism inoperative and another solenoid controls the rotation of a shaft on which are grouped cams actuating machinecontrolling switches. At the beginning of a traverse, the full voltage is applied to the clutch 110, 111, to enable it to transmit a heavy starting torque; but, as the carrier rod is brought up to speed, a resistance is automatically inserted in the circuit, to reduce the torque to a fraction of its initial value.