Grippers only grab every second sheet


My heidelberg windmill feeds and delivers every other sheet perfectly, the ones in between are not gripped at all even though the paper is always sucked up correctly. I have watched closely and it seems that one of the gripper arms does not swing in close enough to the sucker bars in order to grab the paper, whereas the other arm does. Is there any way to adjust the stopping position of each gripper arm separately or does anyone have any suggestions?


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I’d inspect the fasteners for the grippers and ensure they are not loose at all, then mark the grippers “A” & “B”.

I would cycle the press slowly by hand (power off, circuit off), and measure the distance of each gripper from the suckers. I’d also measure the distance of each gripper from the platen just before the press closes completely.

Pictures could be a big help.


Check that your feed board ,the upright lump that the sheets grip edge rests against is in the correct orientation and that there is no paper or card stuffed underneath it .
you may also need to check that the offending gripper is actually closing properly ,if it isnt then adjust the link on the top of the assembly till it grips .
check the gripper is not bent or twisted ,a quick check against the platen surface will tell you if its twisted or bent .

I have had this problem before and what I did was simple, yet will make most windmill users cringe, if everthing seems to be inline(screws tight, gripper bar not cracked) bring your bad gripper bar to where it just starts to go over the platen and give it a firm tug back towards you, you may have to try this a few times but has worked for me in the past.
probably not the best advice but this can also help with registration problems