Web guide roller with directionally switched drive coupling

A device for preventing damage to a production apparatus with rotating cylinders including blanket cylinders in a web fed rotary printing press, said device comprising:

• a first material web gripping location;
• a second material web gripping location positioned downstream in a direction of material web travel from said first material web gripping location;
• a rotatably supported material web guide roller positioned intermediate said first and second material web gripping locations and being rotated in a first direction and at a first rotational speed by a material web passing around said web guide roller;
• a rotatably supported driven shaft driven in said first direction and at a second rotational speed less than said first rotational speed and rotatably supporting said web guide roller;
• and
• a directionally switched coupling selectively operable in response to a break in a material web intermediate said material web guide roller and said second material web gripping location and a resultant decrease in rotational speed of said material web guide roller from said first speed to said second speed to drivingly couple said driven shaft to said web guide roller.