Bishops cam box bush

[Malcolm Taylor]

When bishops cam boxes are rebushed I think it is usual to use phosphor bronze or 'oilite' bushes. I have one which appears to have been rebushed in the past with a steel bush. Is this likely to cause problems, particularly with modern sector shafts made of EN24 or similar steels? Can anyone advise, please? Malcolm TA1250 [Non-text portions of this message have been removed]

[E.Worpe]

Hi Malcolm, I've also come across the use of a long steel bush for the sector shaft bearing. It could be the misguided belief that as the original bearing material was a "steel casting", then a steel sleeve restores it to "new". Not so, the casting was probably a malleable cast iron that would have been kept at red heat for some days to decarbonise it. This would have left a mediocre bearing material, but still better than steel. Given the problems with lubrication of the sector shaft, it seems that leaded bronze bushes might be more suitable for use with an alloy steel that is not particularly hard. EN24T is heat treated for toughness and fatigue resistance rather than hardness. Phosphor bronze performs better with harder surfaces, where it's less likely to seizure, whilst leaded bronze has some self- lubricating properties more suitable for softer steels. Leaded bronze is also easier to machine and one can obtain good surface finishes with reaming for example. I'm not sure about "oilite" bushes, they may not be strong enough to stand the high loads from the sector shaft. Oilite bushes are made from compressed powder, fused together with heat. This leaves them porous and thus more likely to break up. However, it would be worth seeking more knowledgeable advice from the manufacturers. Regards, Eric. -----Original Message----- When bishops cam boxes are rebushed I think it is usual to use phosphor bronze or 'oilite' bushes. I have one which appears to have been rebushed in the past with a steel bush. Is this likely to cause problems, particularly with modern sector shafts made of EN24 or similar steels? Can anyone advise, please? Malcolm TA1250 [Non-text portions of this message have been removed]

[1939mgtb]

Um....needle bearings? Best, Ray "I can't tell the difference between Whizzo butter and this dead crab."

----- Original Message ----- From: "E.Worpe" E.Worpe@surrey.ac.uk> To: "malcolm" malcolm@whisketgreen.fsnet.co.uk> Cc: "mg-tabc" mg-tabc@yahoogroups.com> Sent: Monday, March 21, 2005 4:15 AM Subject: RE: [mg-tabc] Bishops cam box bush > > Hi Malcolm, > I've also come across the use of a long steel bush for the > sector shaft bearing. It could be the misguided belief that > as the original bearing material was a "steel casting", then a > steel sleeve restores it to "new". Not so, the casting was > probably a malleable cast iron that would have been kept at > red heat for some days to decarbonise it. This would have left > a mediocre bearing material, but still better than steel. > Given the problems with lubrication of the sector shaft, it > seems that leaded bronze bushes might be more suitable for use > with an alloy steel that is not particularly hard. EN24T is > heat treated for toughness and fatigue resistance rather than > hardness. > Phosphor bronze performs better with harder surfaces, where > it's less likely to seizure, whilst leaded bronze has some self- > lubricating properties more suitable for softer steels. > Leaded bronze is also easier to machine and one can obtain good > surface finishes with reaming for example. > I'm not sure about "oilite" bushes, they may not be strong enough > to stand the high loads from the sector shaft. Oilite bushes are > made from compressed powder, fused together with heat. This leaves > them porous and thus more likely to break up. However, it would be > worth seeking more knowledgeable advice from the manufacturers. > Regards, Eric. > > > -----Original Message----- > When bishops cam boxes are rebushed I think it is usual to use phosphor > bronze or 'oilite' bushes. I have one which appears to have been rebushed > in the past with a steel bush. > Is this likely to cause problems, particularly with modern sector shafts > made of EN24 or similar steels? > Can anyone advise, please? > Malcolm TA1250 > > > > > > > > > > > > > > [Non-text portions of this message have been removed] > > > > > Yahoo! Groups Links > > > > > > >

[fnitz]

I installed needle bearings but might have done something different if the box had not already been reworked to the point where I had little alternative. I am happy so far with the result and it has the added advantage of providing a good seal at the bottom of the sector shaft (I used one of the Torrington bearings with an integrated seal) so the box remains well lubricated. I also had the sector shaft hard chromed and reground to size at the same time. Fred TC1353 -----Original Message----- From: 1939mgtb [mailto:1939mgtb@comcast.net] Sent: Monday, March 21, 2005 4:28 AM To: malcolm; E.Worpe Cc: mg-tabc Subject: Re: [mg-tabc] Bishops cam box bush Um....needle bearings? Best, Ray "I can't tell the difference between Whizzo butter and this dead crab."

----- Original Message ----- From: "E.Worpe" E.Worpe@surrey.ac.uk> To: "malcolm" malcolm@whisketgreen.fsnet.co.uk> Cc: "mg-tabc" mg-tabc@yahoogroups.com> Sent: Monday, March 21, 2005 4:15 AM Subject: RE: [mg-tabc] Bishops cam box bush > > Hi Malcolm, > I've also come across the use of a long steel bush for the > sector shaft bearing. It could be the misguided belief that > as the original bearing material was a "steel casting", then a > steel sleeve restores it to "new". Not so, the casting was > probably a malleable cast iron that would have been kept at > red heat for some days to decarbonise it. This would have left > a mediocre bearing material, but still better than steel. > Given the problems with lubrication of the sector shaft, it > seems that leaded bronze bushes might be more suitable for use > with an alloy steel that is not particularly hard. EN24T is > heat treated for toughness and fatigue resistance rather than > hardness. > Phosphor bronze performs better with harder surfaces, where > it's less likely to seizure, whilst leaded bronze has some self- > lubricating properties more suitable for softer steels. > Leaded bronze is also easier to machine and one can obtain good > surface finishes with reaming for example. > I'm not sure about "oilite" bushes, they may not be strong enough > to stand the high loads from the sector shaft. Oilite bushes are > made from compressed powder, fused together with heat. This leaves > them porous and thus more likely to break up. However, it would be > worth seeking more knowledgeable advice from the manufacturers. > Regards, Eric. > > > -----Original Message----- > When bishops cam boxes are rebushed I think it is usual to use phosphor > bronze or 'oilite' bushes. I have one which appears to have been rebushed > in the past with a steel bush. > Is this likely to cause problems, particularly with modern sector shafts > made of EN24 or similar steels? > Can anyone advise, please? > Malcolm TA1250 > > > > > > > > > > > > > > [Non-text portions of this message have been removed] > > > > > Yahoo! Groups Links > > > > > > > Yahoo! Groups Links