V-50 cylinder will not go off impression

I have a friend with a V-50 who had his tympan tear and now the cylinder will not switch off impression. when the press gets to the top of the cycle and starts back on the down stroke the cylinder starts turning BACKWARDS. I have never seen this happen before. It appears that the latch on the left side side of the cylinder does not quite engage to latch the cylinder off impression. while turning the press by hand you hear the latch trying to engage but it won’t go down in the groove fully.
I have never had to go into the cylinder to repair anything so I am hesitant to poke around too much. Any help would be extremly welcomed.


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Check all air lines a clue to this is the torn tympan are the airholes at the gripper blocked? This could cause the failure of the pin not disengaging.
Ted Lavin

The pin is disengaging so it will go on impression, it just does not reengage at the top of the cycle. at that point the cylinder begins to rotate backwards when it would normally be stationary. the air lines all look good.
The tympan tore because of overuse when numbering.
Unfortunatly the press is an hour away. I have looked at the v-50 I run where I work but can’t see where the problem may be.


Same issue with self and press miles apart I will keep thinking of about and anything else I will post.

PaulM, it sounds like the brake is engaing the cylinder before it reaches the top stroke,
and not allowing the cylinder stop latch from engaging.
I would also check the pin that disenages the cylinder on the left side of the (operator side) of the press too. This is
the pull out pin to change top sheet.
best james

Have you checked the diaphragm inside the cylinder?