Apparatus for tensioning tape extending between two reels in a tape transport system having servos for controlling the velocity and position of the reels, includes position servo loop for maintaining the first reel in a fixed position. A velocity servo loop controls the other reel for taking up slack in the tape between the reels and applying a relative force on the tape once the slack has been taken up. The velocity servo is limited in the amount of current applied to the motor driving the take up reel by a signal provided by a tension servo connected to the position servo associated with the other reel. In particular, the tension servo responds to the amount of current applied by the position servo for applying a motor-current-limiting signal to the velocity servo system. When the position servo is applying minimal current to the fixed-position reel (when the tape is slack), a relatively large amount of current is allowed to go to the take up reel. As the tape becomes taut and the fixed-position reel is pulled out of position, the position servo applies increasing current to the motor in order to attempt to return the reel to the fixed position. The tension servo responds to the increasing current applied by the position servo, for reducing the amount of current applied to the take up reel motor.

A tape feed control device is configured to detect resolutions of respective reels so as to supply respective reel motors with tension currents i.sub.t1 and i.sub.t2 for setting a tape tension to establish a predetermined tape tension of a tape extending between the reels, and so as to supply the reel motors with acceleration and deceleration currents i.sub.s1 and i.sub.s2 based on an acceleration/deceleration current ratio .alpha. to transport the tape. In this fashion, a desired tape speed is obtained, maintaining a constant tape tension.

An apparatus for regulating the length of divisional spacings of a metal band comprises at least two workpiece conveying roller pairs spaced from one another in the direction of the workpiece length and arranged for holding and advancing the workpieces in the direction of workpiece length; a scanning device for determining the actual length of the workpieces during the conveyance thereof by the workpiece conveying devices; an evaluating device receiving, from the scanning device, signals representing the actual lengths of the workpieces; and a length correcting device receiving, from the evaluating device, signals representing correctional values and for varying the length of the workpieces at a location between the roller pairs as a function of the correctional values. A heat treatment device heats the running band to a temperature sufficient to maintain the band in a red-hot state at the length-correcting location.

An impact printer ribbon drive of the reel-to-reel type, in which a length of ink ribbon extending between and wound around opposite reels is disposed between a reciprocating hammer bank and print paper on a platen, drives the ribbon at substantially constant speed and tension independent of varying ribbon pack diameter on the two reels. Each one of the reels is driven by a different one of a pair of DC permanent magnet motors. The motors are energized by a circuit which maintains the sum of the currents through the two motors substantially constant and which also maintains the voltage at the leading or take-up motor substantially constant. The sum of the currents and the voltage are maintained substantially constant by a pair of servo circuits associated with different ones of the motors and coupled to be alternately actuated in response to external direction commands. Also included is circuitry responsive to voltages in different parts of the circuit for signalling unwanted conditions such as a run-away ribbon, a jammed ribbon or a loose hub at one of the reels.