Improvements relating to drives for strip and like materials

1,098,306. Feeding webs. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. March 18, 1965 [April 1, 1964], No. 13413/64. Heading B6B. [Also in Divisions G3 and H2] Strip 2 is passed from an annealing oven to a coiling station 3 over rollers A-D to form loops X-Z, each roller driving a digital tachometer generator TA-TD providing a specified number of pulses for a unit length of strip passing over the roller. The pulses from the generators are fed to bi-directional counters FX-FZ each arranged to provide an output, corresponding to the total difference count, to an associated digital-to-analogue converter GX-GZ. The D.C. outputs from neighbouring pairs of converters are fed to comparator and control circuits H1, H2, whereby the speed of an intervening roller is controlled to maintain equal lengths of loop. Signals from photocells L1-C3, when the light beam is interrupted, re-set the corresponding counter, if in error, to the loop-length corresponding to the depth at which the photocell is located.