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Another oil thread

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  • Far Canal
    Far Canal
    4 years ago
    Ok, fair enough.
    Only other thing I can think of is the gears are not cut accurately enough.
  • drod
    drod
    4 years ago
    how good are the bearings you are using? New bearing each time you build the gearbox? Nitrile ? (nitride) hardening, good for cams and crankshafts, not so good for gear hardening. case hardening is better for gears. 
  • steelo
    steelo
    4 years ago
    What did engineers say beagle?
  • beaglebasher
    beaglebasher
    4 years ago
    As I  said steelo  I didnt manage to  get to the meeting but apparrently they came to a conclusion.   ( two young engineers )
    Their  conclusion was there is a resonant frequency being produced which is interfering with the harmonic balance of  Albert Einsteins  theory  of Principia  Mathematica

     which is causing a sympathetic vibration and some other fukin bullshit.
    FC nailed it. The major problem with this gearbox is the boss got the gears made on the cheap.  Not cut  accurately enough.


  • steelo
    steelo
    4 years ago
    Hey bb. What was the outcome of this. Did you try the oil. Get the gearbox going?  
  • beaglebasher
    beaglebasher
    4 years ago
    Just got a new batch of gears made last week. We built one gearbox and filled it with a heavy duty diff oil ( not the Redline,  long story )  and gave it a run on the  test bench.  It definitely ran quieter than the other gears but at roughly  3/4 speed it started rattling its head off just like before.  It smooths out if you  increase the speed just like before. 
    We pulled it apart and all the  teeth were intact but it only ran for 20 minutes so its still a work in progress. 
  • Wideglider
    Wideglider
    4 years ago
    BB, what is this gearbox used for?
  • speedzter
    speedzter
    4 years ago
    from what little I can see, I suggest you need bearing support  outboard of the pinion shaft.
  • beaglebasher
    beaglebasher
    4 years ago
    That would definitely help speedzter but there is no way to  do it. 
    Its a PTO from a ride on lawnmower Wideglider.  Still at the  design stage. 
  • beaglebasher
    beaglebasher
    4 years ago
    The small gear is the  drive. Roughly 20mm diameter from memory.  The one that is getting damaged is the driven.
    Not exactly sure how much torque is being transferred but probably too much! 
    An extra bearing would help but without a major re design  there is not enough room. 
    It is  a prototype so there is nothing else to compare it to.  
  • fatbat
    fatbat
    4 years ago
    Hoodeng has said pretty much everything I was gonna contribute 
  • beaglebasher
    beaglebasher
    4 years ago
    This has been a bit of a head fuck allright.    What do you mean by axial grooving Hoodeng? The length of engagement is around 40 mm , again from memory. I havent had much to do with that project for a few weeks cos we are busy with other stuff but I keep an eye on whats going on.
    Again from memory I think it has to handle roughly 130 - 150 lbs / ft . Again from memory I think its supposed to handle roughly 12 KW at the output .
    My personal opinion is it needs a major re design.   If everything was made bigger it would solve a few problems but it would defeat the purpose of what we are trying to do.  




  • beaglebasher
    beaglebasher
    4 years ago
    The 150 lbs/ft is at the output shaft. The ratio is over 5 to 1 so in theory the actual torque on the drive shaft would be less.
    I think  the boss is resigned to the fact it needs to be re-designed but that won't be cheap.
    I had to google  Lewis Formula. 
    Don't know what it has to do with a gearbox but.
  • Far Canal
    Far Canal
    4 years ago
    That all brings back memories of stuff we had to learn at Tech doing the apprenticeship for Engineering Patternmaking.

    Beagle, what sort of implement is the gearbox in question used on?.

  • dicko
    dicko
    4 years ago
    looks like the driven gear, or the drive gear ,is actually twisting out of alignment under load and the teeth will then not mesh in a straight line for the full length of the driven gear. hence chattering etc.  more support needed on both drive and driven gear. which means another bearing.

  • steelo
    steelo
    4 years ago
    This should see you on your way BB. No oil required either. Don't thank me
    legogear.jpg
  • beaglebasher
    beaglebasher
    4 years ago
    There is a lot of good info there Hoodeng. I am just a dirty arsed old fitter but,  I will leave that side of things to the engineer. I saw the reference to the Lewis Formula but it is a bit above my head. 
    As for what the gearbox is to be used for I would rather not be too specific FC. It is still in the development stage and the boss probably wouldn't appreciate it.
    You're right about the extra bearing dicko
    but that means a major re-design, which I think is going to happen. 
    Just saw your photo steelo. I will show it to the boss on Monday.  I am sure he will be impressed. 
  • Wideglider
    Wideglider
    4 years ago
    I deal with repairs & maintenance all sorts of plant machinery everyday, some magnificent & reliable examples, but unfortunately many contraptions that cause no end of grief! Shortcuts in engineering design will come back to bite your arse.
    Applying endless band-aids (extra bearings etc) to hopefully fix these design flaws can just go around in circles. 
    Start again & employ a mechanical engineer to calculate stresses & design a machine to meet the capacity required - money well spent.
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