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  1. AshleyK

    Bearing life calculation for a wind-turbine generator?

    MikeHalloran: I have had a good look online and I still can't find any examples of the calculation, but in terms of historical information we do have turbine logs which will be able to tell us how much time is spent running in star, and how much in delta, which will give us two values to find an...
  2. AshleyK

    Bearing life calculation for a wind-turbine generator?

    Cheers Skogsgurra. I'm aware of the insulation issues for the bearings, and we're currently using some SKF hybrid bearings with silicon nitride rollers. Thanks for the calculation tips, to clarify: If I'm 'calculating for worst case', should I just use the highest speed (1,500 RPM) the...
  3. AshleyK

    Bearing life calculation for a wind-turbine generator?

    Hi, I'm after a bit of assistance with a calculation for a wind turbine generator bearing. I have performed the calculation by hand for other plant before, but obviously the wind turbine operates at a constantly varying RPM, and despite contacting SKF and searching every handbook and engineering...
  4. AshleyK

    HV switching advice for the mechanically mindedà

    Apologies for the vagueness, but I won't actually be 100% certain of the circuit until I've been given further details. I was only promoted on Tuesday. The incoming circuit is 32kV, and the substations convert that to 1000V for our equipment. Is this a decent place to...
  5. AshleyK

    HV switching advice for the mechanically mindedà

    Obviously unaware of the more blatant forms of trade blasphemy, my management team have seen fit to let me (a mechanical engineer) loose within a HV switching role. A recent promotion has left me as an area supervisor whereby any mechanical/electrical bias is basically disposed of and this role...
  6. AshleyK

    Rust on bearing journal?

    I'm not sure on the shaft material but I'll try and find out. As far as I know the rotor weighs 6t. Of the shafts I've measured, they've all been near the top end of that range (170.033), and although I haven't measured any of the bearing bores I'm assuming their tolerances would be pretty...
  7. AshleyK

    Thrust bearing design

    I don't understand where the axial loads are coming from, aside from the shock load when somebody drops the bike on its side. Deep groove ball bearings can take a fair amount of axial load as well. Have you considered a damping washer in between, or on the outside of the bearings to save a...
  8. AshleyK

    Rust on bearing journal?

    I've been doing some calculations for the fit. Our journal tolerances are between 170.015 and 170.033 The bearing coefficient of expansion is 11.7x10^-6 Therefore, 170mm x 11.7x10^-6 x 90 degrees = 170.179mm 90 degrees is the temp change, from the ambient 25 to 115.
  9. AshleyK

    Rust on bearing journal?

    As a quick overview, we're commonly finding that our alternator bearings (6334, so a 170mm ID) have rust on the journal underneath the inner races when removed. The alternators are in a plant room and not exposed to any rain. Has anyone experienced something similar before? The grease system...
  10. AshleyK

    Austenite/Austenitization...

    Thanks very much for all the replies so far. I can't believe our bearings have ever got to anything above 200C, let lane the 700+ needed for austenitization. I'm fairly sure this theory has come from our technology department though, where I'm assuming a removed bearing has been analysed. Is...
  11. AshleyK

    Austenite/Austenitization...

    I'm currently researching a succession of bearing failures as part of a work-related project and I was told that the current theory is based around austenitization (austenitisation, for the UK?) of the bearing material. However, after some Googling and looking through a few of my engineering...
  12. AshleyK

    Austenite/Austenitization...

    I'm currently researching a succession of bearing failures as part of a work-related project and I was told that the current theory is based around austenitization (austenitisation, for the UK?) of the bearing material. However, after some Googling and looking through a few of my engineering...
  13. AshleyK

    In-situ annealing?

    Yeah, maybe a test is on order. Cheers for your opinions, guys.
  14. AshleyK

    In-situ annealing?

    I understand there's plenty of ways to remove the caphead, I was just unsure whether my suggestion was any good. How would heating it to a cherry-red and letting it cool in its own time make it harder? I don't understand that at all.
  15. AshleyK

    In-situ annealing?

    Thanks, swall. If it's any help this was just an M16 mild steel cap head, with 12.9 marked as the tensile. Regular HSS drill bits didn't show a lot of interest and it was sheared off under flush so we couldn't use a centre-pop to unscrew it. I did wonder about sticking this thread in the...
  16. AshleyK

    In-situ annealing?

    Would heating up a cap-head until it is cherry-red and then letting it cool to room temperature reduce the hardness? We were attending a breakdown up high on a crane the other day and found ourselves having to drill out a sheared caphead bolt (I'm a maintenance fitter currently doing my BEng...

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