Patent ID: 8206249

Claim:
A tension head apparatus for use as part of a racquet stringing machine comprising; a snatch vise for engaging a racket string comprising; two spaced apart outer walls defining between them a fixed separation space; two spaced apart vice jaws positioned in the separation space one of which being adjacent to each outer wall and operable to close the distance between them during operation and to have horizontal movement relative to the outer walls; roller bearings set into bearing recesses in each outer wall and the adjacent vice jaw, the bearing recesses having relative bearing wall orientation such that upon rearward movement of the snatch vise with movement of the vice jaws relative to the outer walls, the roller bearings will force the vice jaws to move closer together and wherein the bearing recesses of both the outer wall and the adjacent vice jaw have upper and lower surfaces which overlay a portion of the upper and lower ends of the roller bearings thereby to constrain any relative vertical movement of the outer wall relative to the adjacent vice jaw; a motor assembly operable to drive the snatch vise rearwardly to apply tension to a racket string in the vice jaws wherein the load cell is attached to the motor assembly; a load cell fixed to the snatch vise and to the motor assembly and having strain gauges mounted on it to measure strain transmitted from the outer walls to the load cell during operation; a tension setting element for setting a desired tension on the racket string and transmitting an electrical signal comparable to the tension setting; an electronics assembly for reading the strain on the load cell and comparing it to the tension setting electrical signal and operable to cause the motor assembly to stop when the strain indicates that the desired tension has been reached; whereby upon rearward movement of the snatch vise with a racket string between the vice jaws, the vice jaws will close on the racket string and cause tension on the racket string to the point where the tension setting is equal to the tension on the racket string whereupon the motor assembly will stop.