|
Post by RGR 60130 on Jun 30, 2022 9:54:37 GMT
|
|
|
Post by andyhigham on Jun 30, 2022 10:54:43 GMT
|
|
|
Post by chris vine on Jun 30, 2022 13:06:23 GMT
Hi Pete,
Are you sure you are looking for spherical bearings?
If you are looking for a bearing to go in the large end of the radius rod, surely you are looking for self-aligning ball bearings.
The spherical bearings (like Rose joints) are not rolling bearings at all. They won't be very good at continuous motion I would think.
A self-aligning ball bearing, while not having the same load capacity of a normal ball bearing, does allow the axle to change angle on track irregularities while not trying to twist the radius rod.
If you want higher load rating, you could always go for spherical roller bearings!!!
Chris.
|
|
|
Post by andyhigham on Jun 30, 2022 13:27:15 GMT
|
|
|
Post by Deleted on Jun 30, 2022 13:53:41 GMT
Thank you to everyone who has either commented on this thread, sent me PM's, MSN or the excellently detailed email correspondence that I received from Eddie, a big thank you to all. I also thank the more experienced members of my own club for their input today. There are some great links posted above and one of which I have placed an order for 4 spherical bearings, two as spares. They are cheap which I realise is not the best policy but if they are sound when they arrive, ie no cracks in the outer casing, I think they may be ok. My reasoning here is that for LNER loco's the spherical bearing sits in a grease cap which should ensure a long life. I have followed advice and gone for steel on steel bearings, avoiding those lined with PTFE. This is a close-up of Don's drawing The main issue that I have had is finding a bearing that is narrow enough to fit in the 3/16 width, the bore, and outer dia are not so important as I haven't made the eccentric rods themselves yet. Having said that, the bore must be large enough for the 7/32 threaded pins to pass through as the return cranks have already been made to this thread size. This means that nothing smaller than a 6mm bore is acceptable. I have therefore selected bearing GE6E for my purpose (er A1 Reg.. These are 6mm bore, 14mm outer, 4mm shell case width and 6mm ball width... er I think... They are very cheap, cheap enough to take a look and then use if they look ok, I could buy an awful lot of these for the £240 cost+P&P for the proper aviation-grade Rose RBJ102L's as required by Don. Thanks, Chris, For the eccentric rods, I am very sure that spherical is what's needed. Many thanks, chaps Pete
|
|
|
Post by Deleted on Jun 30, 2022 13:57:01 GMT
That's an interesting alternative Andy, those might also work when sitting in a bath of grease although a little large? Cheers Pete
|
|
oldnorton
Statesman
5" gauge LMS enthusiast
Posts: 696
|
Post by oldnorton on Jun 30, 2022 16:41:42 GMT
I agree with Chris Vine in that I also thought that rose joints were solid spherical bearings i.e. a ball with a socket around it, like a human hip joint. They are used as track rod ends or bearings on gear change push rods, etc. If used as a rotating bearing (big end) I would have thought they should amply oiled.
Grease will last on ball bearings running in a spherical seat, the self aligning ball type.
I am not sure that many other models specify spherical ball big end bearings. For all the engines with plain bearings, on the rare occasions when the driven axle twists out of alignment I think the slop in big and little ends copes. I know you are wanting to make it ultra prototypical Pete, but is Don Young being a bit precious in specifying these bearings?
Norm
|
|
|
Post by Deleted on Jun 30, 2022 17:12:47 GMT
I know you are wanting to make it ultra prototypical Pete, but is Don Young being a bit precious in specifying these bearings? Norm I don't think so Norm, Don is not alone in this. Granted it may not be common place in the model world but I respect Don's design as I do that of the most respected model engineers at my own club who do use spherical bearings. We also have the likes of today's top builders such as Doug Hewson. The only question in my mind is how well will the cheaper bearings cope? The Rose bearing is a high end aerospace item, perhaps it's worth the money? Only time will tell. Pete
|
|
|
Post by ettingtonliam on Jun 30, 2022 18:30:37 GMT
Nothing new! When Robert Stephenson built Locomotion and its siblings in 1825/26, they had spherical bearings for the coupling and connecting rods, a total of 12 in all. I had to produce them for my model, split solid cottered bearings.
|
|
|
Post by chris vine on Jun 30, 2022 22:06:36 GMT
I think that the spherical bearings, like Rose joints, are only intended for modest rotations. IE not for continuous rotation.
I have not looked at the original drawings for A1 A3 etc, but it would be interesting to know what was used in the original full size.
Equally, the amount of angular displacement of the axle is quite small and probably would not distress plain bearings in the large and small ends of the eccentric rod...
Chris.
|
|
|
Post by andyhigham on Jul 1, 2022 8:24:51 GMT
|
|
|
Post by Deleted on Jul 1, 2022 10:12:25 GMT
I have done a little research on the bearings used by the LNER for their eccentric rods. I haven't found a drawing yet but did note some details given in the Haynes book on 4472, Quote: The eccentric rod bearing and reversing screw to be fitted with Skefco ball bearings as shown on the drawings. All the ball and roller bearings must be fitted with great accuracy throughout: end quote. A little more digging and I found that these are SKF bearings and in fact, the design is little changed today and can be found in many applications including today's fastest trains. This type of spherical bearing was invented by Sven Wingquist in 1907 and marketed in 1919, here's the gent with one of his bearings. I even found his original sketch As mentioned, these bearing have seen very little change during their history, today we have this The description given today is thus: Dealing with very heavy radial and axial loads in applications prone to misalignment or shaft deflections? Meet the challenge with SKF spherical roller bearings, whose high load carrying capacity and ability to accommodate misalignment help you obtain low maintenance costs and long bearing service life. SKF invented this bearing type in 1919 and our range is the widest in the industry today – both open and sealed. Our assortment includes spherical roller bearings designed for many applications, including wind turbine main shafts, continuous casters, vibratory applications and high-speed applications, as well as bearings with Solid Oil, split bearings, SKF ConCentra roller bearing units, and, for the harshest operating environments, our SKF three-barrier solution. If I find the LNER drawing or more information I'll share it here. Pete
|
|
|
Post by Deleted on Jul 1, 2022 10:20:21 GMT
Thanks, Andy... I think my options are growing. I haven't ordered these yet but have done a test order for another better-built bearing from this company. I hadn't done so before as I wasn't sure what the width being measured was. I think that I understand the measurement description a little more now and so have also ordered a couple of COM04 imperial bearings with the required 1/4" bore. I now have two different types/sizes of spherical bearing coming, I'll take a look at which one suits my application best. It will be a while before I get to use them what with so much going on in my life just now but I will, of course, give a full report on my blog. Kind regards Pete
|
|
61962
Seasoned Member
Posts: 129
|
Post by 61962 on Jul 1, 2022 11:08:43 GMT
Just for the record the full size bearings were SKEFCO No 1413 or Hoffman U-565, and applied to all GNR/LNER walshaerts gear locos from 1920 onwards and probably the BR Standards as well. These are double row self aligning ball bearing type and often referred as spherical because the outer race is ground thus. Full size dimensions are 160 x 65 x 37mm. Looking at a few sites there are no equivalents for 5" gauge, the minimum OD being 19mm when 9/16" is required, which is presumably why Don Young used the rose bearing for Doncaster. There have been many locos built to this design. It would be interesing to find out what builders have actually done and how the Rose bearings have faired. I know of at least one loco to Don's design that is fitted with plain single row ball races and has been running for 30 years without issues. My own 3 1/2 " A4 is similarly fitted with 5/16 OD, 1/8 bore ball races and has been going for more than 30 years on the same bearings.
Eddie
|
|
|
Post by Deleted on Jul 1, 2022 11:38:19 GMT
Thanks for the info Eddie, I thought/hoped that you would know the answer... Kind regards Pete
|
|
61962
Seasoned Member
Posts: 129
|
Post by 61962 on Jul 1, 2022 14:44:37 GMT
Hi Pete, You're welcome. There is a photo of one of SNG's bearings on this page. It may be the left one that they decided needed replacing during the overhaul. www.sirnigelgresley.org.uk/overhaul-1522/overhaul-10-a.shtml I note Richard calls it spherical. I suppose he should know, he worked in bearing manufacture all his working life! Eddie
|
|
|
Post by Deleted on Jul 1, 2022 15:05:26 GMT
Hi Pete, You're welcome. There is a photo of one of SNG's bearings on this page. It may be the left one that they decided needed replacing during the overhaul. www.sirnigelgresley.org.uk/overhaul-1522/overhaul-10-a.shtml I note Richard calls it spherical. I suppose he should know, he worked in bearing manufacture all his working life! Eddie Thanks, Eddie, you have more stamina than I sir, I started to reread the SNG overhaul pages but gave up after about 10 pages, I was sure that I had seen it there somewhere. Looking at that picture reminds me very much of the CV joints on my car. a similar design and a right pain when the balls fall out during work on the Transaxle. They are very strong, and can withstand extreme torque and speed. A picture for reference.. yes they do a different job but look similar, or they do to me... Pete
|
|
|
Post by chris vine on Jul 1, 2022 16:29:29 GMT
Hi Pete, Yes, I think this is a much better plan than a spherical ball type joint. I don't think that would wear well.
For your application, the self-aligning ball bearing will be perfect. The roller equivalent would be total overkill!!!
Chris
|
|
|
Post by Deleted on Jul 1, 2022 19:35:34 GMT
Hi Pete, Yes, I think this is a much better plan than a spherical ball type joint. I don't think that would wear well. For your application, the self-aligning ball bearing will be perfect. The roller equivalent would be total overkill!!! Chris Agreed Chris, I doubt such things are available in our sizes so a normal spherical bearing will do for starters. After all, if they are good enough for Doug then they are good enough for a mere mortal like myself... Pete
|
|
uuu
Elder Statesman
your message here...
Posts: 2,812
|
Post by uuu on Jul 1, 2022 20:35:13 GMT
I have a personal theory, completely unsupported by any calculated or empirical evidence, that many full size locomotive rods were designed to flex in torsion, so allowing the use of plain non-spherical bearings, without too much slop in the motion.
Wilf
|
|