Oil for sintered bearings

[Boater Sam]

A lot of American electric motors use sintered shouldered and plain sleeve bearings in a housing filled with "Permawick" semi solid lubricant which is a fibrous filler impregnated with oil, looks like wood flour in clear thin oil.
There are windows in the housing so that the lube is in contact with the bearing material at both sides.

[ben]

On a related note, the other day I picked up this 'After run oil' (for model cars or aircraft I believe) which was on offer. I have no idea as to its composition but I hoped it would be thin enough to use on tape decks and record deck pivots, possibly motor bearings. Anyone have any further info or experiences?

[paulsherwin]

It appears to be a synthetic oil of some sort. It's used to prevent corrosion in model engines but there's no knowing what its lubrication properties are like. Maybe there's something on the manufacturer's (German) website.

[Craig Sawyers]

Originally Posted by Station X

For a straight SAE30 oil I use this stuff:-

https://www.screwfix.com/p/no-nonsen...ails_container

Good link - I hadn't though of Screwfix as a source of oil, let alone a single weight SAE30.

Craig

[G6Tanuki]

As others have noted, the traditional pre-installation treatment for these kind of sintered 'oilite' bushes/bearings [as used in their millions in 1940s-1970s car dynamos, starter- and wiper-motors] was SAE30 engine-oil.

Either stand the bushes in oil at ambient-temperature for 24 hours before fiting, or stick them in a pan and heat the oil to 150 Centigrade for a few minutes (to expel the air in the pores) then allow everything to cool so the oil draws-into the pores of the bush.

In the case of old car-dynamos the '3000-mile service' instructions involved squirting SAE30 oil into a hole in the casing to lubricate the bush.

These days SAE30 oil is a niche-market item, generally specified for old-style lawnmower Briggs and Stratton engines. My Honda mower demands 0W-30 fully-synthetic oil!

[paulsherwin]

20/50 is pretty close to SAE30 at room temperature.

[Station X]

20/50 isn't that easy to get hold of these days.

[GMB]

... except from Halfords.

[wd40addict]

I've used some 5W40 fully synthetic on the Brenell idler and flywheel. It's running smoothly so original fault is cleared, but it may be over viscous as the flywheel stops very quickly when the motor stops. Anyone with a MK5 deck care to measure how long their flywheel takes to stop from 7.5/15?

[Station X]

Originally Posted by GMB

... except from Halfords.

Indeed! I see that I have two five litre cans of Halfords Classic 20W/50 oil in the workshop. Don't ask!

There's also a litre of Comma 20W/50. I don't know where that came from, but judging by the price I must have purchased it a long while ago.

Garden centres are a good source of SAE30 in small quantities. Sorry if that's already been mentioned.

[peter_scott]

Originally Posted by wd40addict

I've used some 5W40 fully synthetic on the Brenell idler and flywheel.

That would be my choice. Modern fully synthetics are nice and thin for finding their way into tight spaces but also have a stickiness that prevents them from draining off.

Peter

[wd40addict]

I have realised there's another dimension to this: the self aligning bearings on the Brenell flywheel shaft are doing a poor job of aligning.

Obviously if they don't line up perfectly extra side load is placed on the Shaft making oil choice a bit academic.

Does anyone have any tips for persuading elderly self aligning oilites to align?

[Synchrodyne]

Some information on lubricants for Oilite bearings is provided here: http://www.bearing.co.il/OILITE.pdf.

From page 4 of that document: “Oilite bearings are vacuum impregnated with a filtered oxidation and corrosion inhibited turbine oil.”

Considering the long life (perhaps a decade or so) expected of these bearings and their lubricants, oxidation inhibition is a key aspect. Even at moderate temperatures, oxidation (which results in thickening and the formation of gums, etc.) still takes place, albeit slowly. (The oxidation rate approximately doubles for every 10°C rise in temperature.) Something to note is that yellow metals, as often used in the bearing types at interest, are quite pro-oxidant.

Turbines oils are very well oxidation inhibited. So are modern engine oils. But straight mineral so-called engine oils intended for vintage equipment are much less likely to contain oxidation inhibitors in any quantity, if at all, so are contra-indicated. Modern engine oils are generally reasonably benign in terms of matrails compatibility. The zinc dithiophosphate additives (or really their degradation products) that are almost universally used in engine oils are, in isolation, potentially corrosive to yellow metals, but the detergent-dispersant systems of engine oils provide an alkaline and peptizing environment that neutralizes and/or sequesters the potentially harmful molecules.


Cheers,

[crackle]

Originally Posted by wd40addict

I have realised there's another dimension to this: the self aligning bearings on the Brenell flywheel shaft are doing a poor job of aligning.

Obviously if they don't line up perfectly extra side load is placed on the Shaft making oil choice a bit academic.

Does anyone have any tips for persuading elderly self aligning oilites to align?

A gentle tap on the shaft or flywheel with a padded hammer should help align bearings which rotate in a spring housing.

Mike

I always thought the terminology was 5W (behaves like a viscosity 5 in "W"inter) /30 (behaves like a viscosity 30 under 'normal' conditions). Early oils where pushed to get to 20W/50 but these days 5W/40 is the norm. Back nearer to the topic, self aligning bearings usually line up with the knocking about in the installation process of the rebuilt motor. And certainly do on the first run.

[G6Tanuki]

Usually for small Oilite-type bearings in things like record-player motors and car windscreen-wiper motors the bearings are 'self aligning' by virtue of the oilite bush being some form of sphere/egg-shape which fits into a hemispherical housing and is retained by some kind of spring-mechanism (a pressed spring-steel washer being common) so the spherical bush can 'settle' into its hemispherical housing and take up the correct axial alignment.

Only time I've ever known this fail is when the grease has hardened and actually stuck the bush into its housing so it can't realign itself after maintenance has been undertaken on the motor. 50-year-old grease can be terribly retentive!

[D Cassidy]

Originally Posted by Craig Sawyers

In post 19, that is precisely what I suggested - Comma SAE30 classic motor oil.

Hello.
Absolutely the correct oil. Also if you can, allow the bearing to soak in the oil for 24 hours and at around 60c.

[wd40addict]

I have now dissembled the Brenell flywheel bearing and I now understand why the self alignment is so stiff: The first picture shows the component parts, A is the machined aluminium housing, threaded at the back, B is the brass nut that screws into it. C is a felt oil reservoir and D is the oilite bearing itself. There is one of these assemblies each side of the flywheel.

The second picture shows the parts assembled. B has been tightened at the factory by knocking round with a centre punch in the small hole! Maybe when new the oilite could still align, but 50+ years later it's basically being clamped in place.

I have degreased it all and am currently waiting for a lighter oil. I feel 5w40 is too viscous. I'd like to see this flywheel freewheel like my Cossor.

If there are any Brenell Mk5 users reading this how long does your flywheel spin for after switching from 'play' to 'stop'?

[Trigon.]

I've found in similar circumstances that a poor bearing alignment can have a very much greater effect on drag than changing the grade of oil ever could.

Cheers

.

[Station X]

I would suggest that the threaded brass inserts should be tightened whilst rotating the shaft.