Roller clutches (sprag bearings) ?
dhutch - 18/3/11 at 09:39 AM
Seeing as it appears there is nothing that the population of LCB doesnt know something about. Small sprag bearings.
Ive got a mechanical lubricator for a steam engine that uses a pair of them to index the camset around (one to hold back and the other roll on) and
the roll on clutch is starting to slip. I understand 'the only thing you need to do' which these small drawn cup bearings is ensure the
press fit is correct and deforms them inwards, else they slip.
The bearings are as far as I can see marked NSK/TORR FCB-10 (it could FOE-10, the last two letters are less well formed) which gives a bearing
20*16*10 which is about right. However my shaft is 10.6mm an the outside dia about 16.5, which does look a bit like someones ignored the one golden
rule when making it. Can any one suggest if this all sounds likely? At £25 with postage it looks like im going to buy a pair and try them. its done 15
years in its current state and im not about to remake the housing and turn .6mm of the shaft as im already pushed to get it all back together in time
for easter (promised myself and others it will be done for this time!).
Thoughts on a postcard?
From suppliers site: The size as follows: (Fw) 10 mm (D) 16mm (C) 20mm
richardlee237 - 18/3/11 at 10:07 AM
From your sketch it looks as if they are rollers running on an inclined plane. (Rather than the rocking wedge type ) Ususally this arrangement is very
relible, but the rollers can stick due to accumulated sludge in the housing preventing the rollers running up the plane. A good wash out in paraffin
and a light re-oiling often does the trick.
If the tracks are worn a bit of stoning to get the high spots off, sometimes works.
Mr Whippy - 18/3/11 at 10:09 AM
why are you looking at the sizes in mm? surely this would have been made using imperial sizes?
britishtrident - 18/3/11 at 11:31 AM
quote:
Originally posted by Mr Whippy
why are you looking at the sizes in mm? surely this would have been made using imperial sizes?
That was my gut reaction also but works out something like 13/32" and 21/32" anadi (as near as damm it)
Mr Whippy - 18/3/11 at 11:42 AM
quote:
Originally posted by britishtrident
quote:
Originally posted by Mr Whippy
why are you looking at the sizes in mm? surely this would have been made using imperial sizes?
That was my gut reaction also but works out something like 13/32" and 21/32" anadi (as near as damm it)
yeah but unless this engine is recently built i.e in the last 20-30 years it's unlikely to have been metric. Bearings can be difficult as some
sizes are press fits or preload sizes. The axle and diff for my Falcon is metric but some of the sizes were very odd, some were round numbers like
40mm others came out as 37.8! eh? but then this is why they were pressed on to the shaft...
[Edited on 18/3/11 by Mr Whippy]
dhutch - 22/3/11 at 05:20 PM
quote:
Originally posted by richardlee237
From your sketch it looks as if they are rollers running on an inclined plane. (Rather than the rocking wedge type ) Ususally this arrangement is very
relible, but the rollers can stick due to accumulated sludge in the housing preventing the rollers running up the plane. A good wash out in paraffin
and a light re-oiling often does the trick.
If the tracks are worn a bit of stoning to get the high spots off, sometimes works.
No noticeable wear or damage to the shaft.
If it comes to it (like i dont get any asap) i will try a good clean and refit.
quote:
Originally posted by Mr Whippy
why are you looking at the sizes in mm? surely this would have been made using imperial sizes?
The engine was built in 1991 and although the bulk of the engine is build to imperial sizes with whitworth threads the majority of the ancillaries are
metric.
Daniel
