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<DIV><EM>The three main types in modern clappers are timber (genarally lign=
u=20
vitae, I believe), nylon-type materials, and brass or bronzes. Timber ones=
=20
aren't used now, so it's between the others. personally, I think the nylon-=
type=20
ones are crap. They wear out far more quickly than metal bushes, and when f=
airly=20
new have a tendency to swell up in warm weather and bind on the pin, causin=
g the=20
clapper to stick.<BR><BR>The most often used type of metal bush is that of=
=20
oilite, which is an oil-impregnated phosphor bronze. Taylor's certainly use=
this=20
(I've has some clappers rebushed by them fairly recently), as do a number o=
f=20
other firms although I couldn't say specifically which ones without=20
checking.<BR><BR>I'd advise that you recommend oilite.<BR><BR>David</EM></D=
IV>
<DIV><EM></EM> </DIV>
<DIV>Not quite so fast, David!</DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Yes, nylon has been used for clapper=
=20
bushes and it can swell, causing clappers to stick. However, =
;most=20
bellhangers now use Tufnol, which doesn't swell and doesn't cause stic=
king.=20
This seems to wear acceptably well in the great order of things. The big=20
advantage of tufnol is that it is self lubricating and therefore is well-su=
ited=20
to being used in installations that get little or no maintenance.</FONT></D=
IV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Lignum vitae is the traditional material f=
or=20
clapper bushes. It is the densest of all timbers (it sinks in water) and ha=
s=20
natural oils that allow a fair amount of self lubrication. It is now much r=
arer=20
than it once was, but I understand that it is possible to get lignum vitae=
=20
clapper bushes if you know where to go. Another advantage of lignum vitae i=
s=20
that it absorbs shocks fairly well (as does tufnol).</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Bronze, usually in phosphor bronze form be=
cause of=20
its self-lubricating properties, is used for bearings=20
commercially. It is used (but not exclusively so) for Oilite bush=
es. I=20
think oilite is fairly new on the scene - but possibly as long as tufnol. I=
=20
cannot think bronze in any form has the same shock absorption properties as=
=20
lignum vitae or tufnol. Apparently, machining/reaming oilite to size has to=
be=20
done very carefully with a very sharp tool, otherwise the pores c=
an be=20
burred over and then no lubrication results.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I came across a very interesting bushing m=
aterial a=20
few years ago: white metal. The shock absorbing properties and wearability =
of=20
this material is excellent. It used to be used on big ends of petrol=20
engines and therefore it had to withstand the shock loads from the pis=
tons=20
having big explosions above them every other revolution. I think the shell=
=20
bearings now used in engines still employ white metal. Someone had cas=
t=20
white metal into the eye of a 1928 Taylor clapper. It had been reamed out t=
o the=20
size of the clapper pin. The other clappers (lignum vitae bushes) were bein=
g=20
send off to be rebushed. It was a shame to send the white metal one, becaus=
e=20
there was virtually no wear in it. However, it was. In retrospect, it would=
have=20
been useful to monitor its performance.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>The biggest reason for clapper bushes wear=
ing is=20
lack of lubrication. Old-style clapper pins had Stauffer lubricators for=20
greasing the bushes. It is probably quite rare to find a new clapper pin wi=
th a=20
facility to grease. It is clearly very difficult to get grease properl=
y=20
into the bush if the pin hasn't a grease channel - and a lot of greaseway p=
ins=20
have been exchanged for solid stainless steel ones. I quote below an=20
extract from a bellhanger's sales blurb:</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV>We have found most so called 'self-lubricating' clapper bushes to have=
an=20
unacceptably short lifespan and many to have a tendency to seize up in warm=
=20
weather. "Oilite" is a type of lubricant impregnated phospher bronze that w=
e=20
have found to have at least a comparable lifespan to other 'self-lubricatin=
g'=20
materials even when grease is never applied to the clapper joint. If grease=
is=20
applied to the clapper joint via a Stauffer lubricator a couple of times a =
year,=20
we don't know how long an "Oilite" clapper bush will last because we haven'=
t yet=20
found any which have worn out when kept properly greased.</DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Note that they recommend lubricating oilit=
e bushes=20
with grease. </FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>When I argued a point with Alan Hughes&nbs=
p;about=20
lubricated bushes and greaseway steel clapper pins always being b=
etter=20
than self-lubricating bushes (tufnol) acting on solid stainless steel pins,=
he=20
said, "yes, I agree; but the vast majority of my products are going to plac=
es=20
where they will never get any maintenance. On that basis, this is the best=
=20
arrangement". Difficult to argue against that one.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Another reason for wear is over reaming. I=
f the=20
bush has excess clearance, the shock loads will increase this very=20
quickly.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>What would I use? Lignum vitae if I could;=
but=20
oilite does sound interesting. Do not write-off tufnol, though. I've h=
ad=20
fairly decent wear out of this material (but it was greased); and none of t=
hem=20
swelled to cause binding. </FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial><FONT size=3D2>Don't forget to lubricate=20
regularly...<FONT> </FONT></FONT></FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Chris Povey</FONT></DIV></BODY></HTML>