nightjar nightjar@ wrote:

Creating an even suspension of lead in bronze is not that simple, so they
are not cheap, or at least they weren't when I used them. I suspect that
many plain bronze bearings these days are just that: plain bronze.

'Twas ever thus, surely? The most common type is just sintered bronze
alloy, impregnated in oil. The trade name "oilite" came to mind and
Google soon led me to http://www.bsaoilite.com.

The following is copied from their standard range brochure which can be
downloaded from
http://www.bsaoilite.com/content/ind...=67&struid=104

quote
Standard OILITE bearings are impregnated with a highly refined mineral
oil to ISO VG (SAE 30) having a high viscosity index and containing
anti-oxidant, anti-rust and defoamant additives.

A replenishment of oil should be carried out after 1000 hours of use or
yearly. These intervals can be extended for bearings with relatively
thick walls and shortened for low porosity bearings. Bearings running
submerged in oil or in oil-splash will not require replenishment.

A wide range of operating temperatures are [sic.] available. Please
contact our Technical Department on +44 (0) 1473 233300.

To prevent possible seizures with stainless steel or hard-chromium
plated shafts, an addition of molybdenum disulphide to the impregnation
oil must be specified.

Any particular application thought to be outside standard conditions
should be referred to our Technical Department who can be contacted on:
+44 (0) 1473 233300.

However, here are some basic rules:
1. Low viscosity oil for low temperatures, high speeds or light loads
2. High viscosity oil for high temperatures, low speeds or heavy loads
3. High viscosity index oil for wide variations in operating
temperatures
4. Oxidation stable oils for long-period usage
5. Oil with ‘oiliness’ additives for boundary conditions
6. Oil of lesser ‘oiliness’ for full film (hydrodynamic) conditions
7. Oil with Extreme Pressure (E.P.) additives for very heavy or shock
loads
/quote

--
Andy