Demand responsive positive feed device for knitting machine

Claim 1

In a knitting machine of the demand type comprising a plurality of yarn packages for supplying yarns upon demand to a plurality of feeding stations via a plurality of positive feed devices, and wherein said positive feed devices comprise a plurality of rotatable rollers associated with a driven tape running along the surfaces of said rollers, the width of said tape being less than the axial dimension of the running surface of each roller whereby a yarn supplied to one of said rollers at a first position between said tape and the running surface of the roller is positively fed to one of said feeding stations whereas a yarn supplied to said one of said rollers at a second position on the running surface of said roller axially displaced from the tape is not positively fed to said one of said feeding stations, and wherein each of said positive feed devices further includes a bracket having inlet and outlet eyelets disposed at spaced locations adjacent the running surface of said roller, said bracket being selectively displaceable between said first and second positions to locate a length of yarn which extends along said running surface from one to the other of said eyelets for positive feed or nonfeed in dependence upon the position of said bracket, the improvement wherein each of said brackets in each of said feed devices is mounted for free pivotal movement through a limited arc adjacent its associated roller, counterbalance means comprising a pair of counterbalance weights, said counterbalance means including mounting means on said bracket comprising a pair of arms located on opposite sides of the pivot point of said bracket, each of said arms including one of said counterbalance weights, said pair of said weights being arranged to normally urge said bracket and its eyelets into said second, nonfeed position adjacent said associated roller under the influence of gravity, and yarn guide means carried by said mounting means for engagement with the yarn in said positive feed device, said yarn guide means being responsive to the presence of a preselected tension in said yarn resulting from a yarn demand by one of said feeding stations for pivoting said bracket against the force of said counterbalance means thereby to displace said bracket and its associated eyelets into said first, positive feed position, whereby the occurrence of tension in a particular yarn due to a demand for said particular yarn by one of said feeding stations automatically positions the demanded yarn in proper position relative to its feed device for positive feed to said feeding station whereas absence of demand for said particular yarn by said one of said feeding stations causes said counterbalance means to automatically position the nondemanded yarn in a different proper position relative to its feed device for nonfeed to said feeding station.