sensing a slight displacement of the lever or by a separate sensor such as a micro switch hall effect sensor or other position detection means once the free end of the wire 46 is detected the motor driving the pinion 118 is stopped and therefore the wire does not advance any further at this point the solenoid coil 26 is then de energised which causes the plunger 28 to be retracted by a spring not shown which releases the two clutch levers 32 so that their respective compression springs 36 act to press their lower arms against the two ends of the wire loop and therefore hold the wire 46 in place the wire feed motor is then driven in reverse i e to drive the pinion clockwise in order to retract the wire 46 upwards as viewed from fig6 and so apply tension to the wire loop which draws the wire in around the reinforcing bars 2 see fig5 a fig5 b shows detail of the clutch lever 32 on the feed side clamping the end of the wire 46 a similar arrangement clamps the other end of the wire as explained above as the wire loop gets tighter the tension in the wire 46 increases this translates into an increase in the torque applied by the pinion 118 to the driven roller gear 102 the result of this is a tendency for the pinion 118 and roller gear 102 to.