Gentlemen,
Thanks for your responses, I'll endeavour to answer each point.
DiamondJim
1. Materials for Races.
I have previously used the 41 and 43 series steels for various load bearing services, eg rollers, and saw a reference to 62100 from a FAG sheet. I will follow up on the 52100 and 8660.
2. Serial Number
Unfortunately the bearings do not have a serial number (or if they did it is not there anymore!). The bearings seem to be a custom fabricated, or special, design.
3. Hardening to 5.5/6.5mm won't be required for this job, just that I have done up to this depth previously, and anywhere in between is possible. The loads in this application are a lot less than previous, and shared over a greater contact area, so the depth could be a lot less (I will confirm this with the manufacturer we use).
4. The balls are shipped separately. Size is 1-1/2 and 1-7/16 inch, 48 off each size. The 1-7/16 serve as spacer balls between each of the 1-1/2's and hence there is no cage. Refer to Qu: at the end.
5. Firstly, the two bearings are installed horizontally with suspended loads of rake (DN910) and turbine (DN1200).
Note these are nominal sizes only as measured roughly on site.
One of the two bearings is could be primarily designed for axial load, this is the one with the spacer balls and the two races. The load is the axially suspended turbine. It has a small radial component from the pinion drive.
That being said the upper race exhibts sustantial wear on the inside while the lower race exhibits substantial wear on the outside (cold flow, cold working and spalling).
The two races, top and bottom are cut in a flat bottomed weir profile (hope that makes sense?).
6. Yes, Bearings in this size are definitely not "off the shelf" in my experience.
Hippo41 (Lester)
Lester, interesting that you refer to a slewing bearing, I am following up with crane contacts as we speak(type).
7. The lower bearing does feature the 4 inserts I referred to (this bearing carries the rake). Each insert is approximately 10mm wide, and depending on location (top or side) is curved in the appropriate diameter. I am not sure if the inserts were one piece and therefore a whole circle or if they were split into smaller arcs. The inserts have worn down so far it is impossible to tell. I suspect one piece but one of the old stores guy recollects arcs, which raises the question as to how the inserts were held in place, press fit perhaps (a bit difficult for the inner and outer "side" insert race)?
I take it that the technical name for these inserts is "wores" from your reply?
8. I have a cross sectional drawing (1979, paper only) but it is undimensioned so not worth too much. On site measurements are hampered by location (in situ), size (bigger than our current largest micrometer and calipers) and design (there is a large raised boss in the centre). The matching top half is too tight to fit a micrometer in.
9. Currently our bearing suppliers are saying supply of the balls is OK but not the races (turbine) and "wores" (rake).
10. The rake features 86 0ff 1-1/4 inch balls, with no spacer balls or cage.
11. I take it from your "bespoke" comment that the inserts actually come as arc segments of the total diameter? Is this the case for the inner and outer sides as well as the top and bottom? (Refer to comments in Item7)
Our aim is now to return the unit to service with, hopefully, enough information to fabricate roughly m/c'd components. In 12 months we will strip and remove the whole drive assembly and then harden and final machine the new races and balls. Aim is to minimise downtime to under a week.
With the Rake we are considering fabrication of angle races,
inner and outer "L" shaped with the balls to go in between (wish I could insert a drawing!) and machining up the lower rake drive to suit, then putting in the two matching halves instead of the top, bottom and side inserts ("wores"

.
Qu : How do you calculate the diameters (inner, outer and centre) for the bearing when you know the number and size of the balls? Is there a simple formula for this please?
Thanks and regards
Simon