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Van Norman #12 gearbox

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  • Van Norman #12 gearbox

    I've been steadily working on this #12 for a little bit now...minor probs here and there,mostly leaks (if theres a seam there it'll leak shortly ). Heres the question for everybody.....the power feed gear box seeps around the change lever shafts,quite heavily in some cases...after taking apart I found there is no seal to speak of there.After thinking about this,and being that the shafts are a pretty tight fit in the bore,it almost seems as if the oil is getting warm under use and "pushing" out...does this gearbox not have a vent of any sort?..(theres none that I've found)...after machine sits overnight and then gets put into use,can the temp difference cause this? I did take the time to convert the drive to a belt to get rid of the worn out howling chain,but that didnt seem to make a difference one way or other....

  • #2
    what did you use to convert to belt ? Any part number would be appreciated. I Need to convert my #12 eventually.


    • #3
      are you talking about the gearbox in the back of the machine? The one that has its own separate motor? If so, there is supposed to be a separate oil level sight glass on the right hand side (looking from the front of the machine) for this gearbox, and the correct level is about halfway up the side of the box. I NEVER get any oil up high enough in this box to get a significant leak (tho I do get a SMALL seepage, just enough to collect dust), I have never had to add oil to this box in the 10 years I have owned it.

      Check yours and see if it is there. How do you tell if there is enough oil in the gearbox? I think filling it up enough to get leakage out the change lever shafts out the top of the box is WAY too full.

      PS: Mine leaks out of the main gearbox a LOT, I have to have a shield to controll the leakage, I need to get into that box and replace the seals but oil is cheap!

      Last edited by Steve Steven; 03-14-2009, 12:00 PM.


      • #4
        I dont have any part numbers on the pulleys,I scavenged them from the squirrel cage blower in an air handler....the smaller on the motor was dead nuts fit...the larger on the gearbox was right on for o.d. but I had to make a bushing for the shaft. Otherwise,took a few trips to the auto parts store for the right v-belt,I'll get that part number for you over weekend.If you need specifics on dimensions I'll measure what I used and drop a pm to you.
        Steve, talking about the gearbox on back of machine. Its not over full of lube,sets about halfway in the sight glass...I cant imagine oil ever slinging out around those shift shafts...thats what makes me think it has to be temp difference making it build pressure and "push" a little out. Its not running off in the floor,but is enough to annoy me. Think I'm gonna try a small vent like is used on equipment gearboxes and see if that makes any difference. Wondering if there may be a bearing on the way out heating up,but it doesnt seem to matter how long or fast I run it,same results. The main gearbox on this one leaks as well,but most of it is between the swivel and main box,and its not bad at this point....drop or two a week.


        • #5
          How heavy of oil are you using. It may be too thin . I use Mobil DTE extra heavy ISO 150 in my # 12 and have never had any leaks . Fill to center of sight glass only.
          Every Mans Work Is A Portrait of Him Self


          • #6
            hmmm....hadnt considered that. I honestly have no idea whats in it,other than checking the level to make theres enough in it to try it out while I work on it and clean up. I'll drain and refill....thanks Lane.