sm74 feeder clutch timing

Discussion in 'Heidelberg Printing Presses' started by jazzygwd, Jun 18, 2013.

  1. jazzygwd

    jazzygwd Member

    Joined:
    Oct 2012
    Messages:
    17
    Location:
    sw england
    hi all

    i wonder if anybody has a simple answer to my question and any help would be muchly appreciated.

    i have a sm74 1999 5 col and the timing has become eratic ....i.e stopping and starting on all stocks randomly. feeder wheels are set correctly and timing of the sheet is perfect on crawl to front lays via inch button.

    i noticed that the compensator c.i.d is sparadic during running so investigated into the motor first then the clutch which is virtually down to rivets....

    obviously i have tried to replace the outside part what hold the new cluth plate but the feeder wouldnt engage

    my question is do i need to put the second electro part on what engages the gear to this and does it need to have a special set up procedure i.e spacing or electric resyncing only an engineer can do...

    seems weird as it is on two wires on both parts

    any help or knowledge would be appreciated
     
  2. exheidmech

    exheidmech Senior Member

    Joined:
    May 2009
    Messages:
    674
    Location:
    USA
    Couple of things for you to check here. First, you didn't mention what degree you are setting feeder timing to so I thought I would mention that sheet should arrive at headstops at 300 degrees, of course assuming your feeder head timing and forwarding wheels are set correctly. Second, make sure that your head stops are coming back toward the feed board and making positive contact with the feed board. To confirm this I use .03mm feeler stock or thin paper. Put it between the feed board and head stop. You should be able to pull paper out with FIRM pull. If this is not possible you need to check the cam follower underneath the feed board in the center. Very common for this cam follower to be worn as there is no way to lubricate it. Also, on your version of SM74 it is very common for the small pins which limit your headstop on/off bolts to be broken. When these pins break, pressmen like to tighten these bolts completely which then pushes the headstops way too far into the press allowing the sheet to advance way farther into the machine than the front alignment eyes are expecting resulting in constant overshooting sheets at infeed. My guess is your feeder clutch is ok and your cam follower under feed board is bad.
     
  3. jazzygwd

    jazzygwd Member

    Joined:
    Oct 2012
    Messages:
    17
    Location:
    sw england
    thankyou for replying exheidmech.... i checked what you said and the front/head lays reach at about 285 degrees the paper dont reach until 325 degrees which mean they are too late and which means i guess the timing is out..

    not sure if that amount is 1 tooth of the cog slipped or just slightly out and needs adjusting.
    is there an relatively easy way to adjust? if so any guidance would be needed in my case.

    have not had time to check the cam i must be honest and the timing of the sheet from feeder head is when the forwarding suckers are fully forward the wheels are just starting to touch the paper to push down the feed table. is this correct?

    cheers
     
  4. exheidmech

    exheidmech Senior Member

    Joined:
    May 2009
    Messages:
    674
    Location:
    USA
    To properly set feeder timing you need to set feeder head timing first. To do this, first you need to adjust the pretention on the forwarding wheels. Inch the feeder forward until the wheels are in the complete down position against the forwarding shaft. Loose the knurled jam nut. Adjust the distance between the jam nut and the forwarding wheel to .10mm or .004" inch. Once this is done, next you will set the feeder head timing to feeder. To do this you must engage the feeder and simulate feeding a sheet. All suction to feeder head and forwarding suckers must be on. Place small sheets of paper in the forwarding suckers. Slowly inch the sheet forward until the forwarding suckers drop the sheets. At this point the forwarding wheels must be 1mm or .040" inch above the forwarding shaft. Make this adjustment at feeder head drive shaft in the feeder head. than adjust the your feeder timing to 300 degrees.
     
  5. jazzygwd

    jazzygwd Member

    Joined:
    Oct 2012
    Messages:
    17
    Location:
    sw england
    thanks exheidmech....i did what you said. the timing of the sheet is now at 305 degrees and the press is not cutting out all of a sudden like it was. hopefully this has cured the problem but i will test it on numerous stocks and if still encountering issues may i pick your brains agian but for now all i can say is thank you

    one thing to note is that the compensator motor is not taking too long to find itself now so thats also a good point.

    one other thing i would like to ask and it is probably a qualified engineer job but is it major difficult to set up the perfecting pincer grippers?
     

  6. exheidmech

    exheidmech Senior Member

    Joined:
    May 2009
    Messages:
    674
    Location:
    USA
    Short answer, nobody should touch pincer grippers without proper training.
     
Loading...