Web infeed mechanism

An improved web infeed mechanism feeds a web of material to receiving rolls of a printing press and includes a web drive roll which is driven from the main press driveline through a chain drive assembly and harmonic drive unit. A hollow dancer roll is pivotally mounted on a pair of support arms and is pressed with a constant pressure against a bight portion of a U-shaped loop in the web by a pair of air cylinders. Upon movement of the hollow dancer roll from an initial position, a resilient member is flexed to change the resistance of a plurality of strain gauges on the resilient member. This results in a change in an output signal from a circuit containing the strain gauges and which signal is utilized to activate control apparatus to vary the peripheral speed of the web drive roll. This control apparatus includes a reversible permanent magnet control motor which is connected by a belt drive to a wave generator in the harmonic drive unit. To provide for an accurate response at different press speeds, the control apparatus also includes a tachometer which provides a signal which is directly proportional to the speed of rotation of the receiving rolls. This signal is multiplied by the signal from the strain gauges to provide an output signal which is utilized to energize the permanent magnet motor and vary the peripheral speed of the web drive roll upon movement of the dancer roll or a change in press speed.