Bicycle (wheelchair) bearing grease ?

Funny you should mention this. It seems that for over 2 decades the industry and various countries have been trying to agree a set of specs for the running gear of wheelchairs. One of the biggest problems is that transport manufacturers want to include locks for them so they can strap them down easily. at the moment there are over 200 designs and variations. I'm not surprised that brakes are rubbish and castors wear. We used to have castors on an oscilloscope trolley that was over 30 years old and nothing had worn. The inability to design for the real world for persona carrying devices seems bleedin criminal.

Brian

Power chair or manual?

I have a pair of drum brake wheelchair hubs that look similar to Sturmey Archer stuff that usually lasts very well, but I guess there might be a difference in the materials.

If you can knock the bearings out and prise out any rubber seals or metal shields you can wash them out with paraffin or white spirit and pack them with grease. Regular lithium grease can be had in a little tin or tube on eBay for a couple of quid, but it's much more economical in a tub. The bearings are actually pretty cheap to replace anyway (depending on size, I guess, but I've not had any trouble finding them for manual chairs for a few quid) and less hassle than trying to revive tired ones.

CV joint grease. Black moly grease, also the same stuff used to grease an SDS drill chuck.

You can get the former from any garage because it generally comes as part of CV boot kit, and they'll always have odd ones.

Or cycle lithium grease might be ok, available in small tubes from cycle shops.

How accessible are they? Are they "proper" ball bearings with an inner and outer race and a trapped set of balls, or are they something like old fashioned bicycle bearings (i.e. two outward facing "cups" and two inward facing "cones").

If they are "proper" ball bearings are they sealed, with a rubber seal between the inner and outer races, or shielded, with a sort of metal washer fixed to the outer, and a small clearance gap to the inner.

It's sometimes OK to oil ball bearings, but you need to keep doing it: all depends on load, speed, mileage, etc. No point trying to oil (or grease) "sealed" bearings.

I'd say that in this application, the type of grease is not particularly critical. CV grease is OTT in performance and stains clothing, but the fluidity might help. Even vaseline would work, especially on the "swivel" bearing.

For small quantities, it's either a fiver from a bike shop, or blag an egg-cup full from someone with older cars or motorbikes.

They're sealed units ...

Brilliant tip !

Of course :)

With sealed BB bearings I've carefully removed the /inside/ seal, washed out the bearing and repacked it. Clip in the seal and refit.

Hypodermic with thin grease can sometimes get past the rubber.

For my bicycle bearings, I use Finish Line premium synthetic grease. It's Teflon loaded, doesn't separate, water repellant, and it's white so you can tell when it's getting dirty and needs replacing. The large tub I have is 20 years old, but it looks like you can still get it, and it comes in small tubes too. I have not ever tried this on pre-assembled bearings though.

For pre-assembled bearings, I use WD40 to wash out the grease and clean bearings first - keep washing through and spinning until the WD40 is coming through clean. Then I use compressed air can to blow out the WD40 afterwards (avoid blasting it into your face or anywhere where the washed out dirt will stain). Leave to dry too - probably don't want it mixing with real grease. I use real grease for these, not the bicycle grease.

Also note that pre-assembled bearings are generally very cheap for what they are, providing you go to a generic bearing supplier and don't try to source a specific spare part for the appliance. You then get the options of sealed or non-sealed, etc. Most bearings are industry standard sizes.

Getting old bearings off can be difficult in some circumstances though. I did once have to cut through both sides of a washing machine bearing with a dremmel fitted with a tiny angle-grinder disk to get it out from the drum - that took 2 evenings and I probably wouldn't have bothered if I'd known how difficult it was going to be. (Washing machine still working some 3 years later as a consequence though.) You can get bearing puller tools in various sizes/configurations, but even that can't pull a bearing off a rusted shaft.

There are tools to press grease into bearings, two cones you wedge the bearing between and press grease through the bearing.

A look through the web brings up "Handy Packer" and "bearing packer". Some of these use a grease gun, and so would have enough pressure to press grease through a small hole punched in the seal.

Or this random video:

which also shows a "grease injector needle".

That said -- this is true:

Get a dozen new ones off the bay, install, done. Money (and time) for a bearing packer might be better spent on a bearing puller and maybe a press...

Thomas Prufer

Correct, I should have said no point trying to relubricate them without doing something invasive. Actually often worth removing both seals, so that you can flush it through with something like WD40 before regreasing.

And as you say, if they have gone "stiff" it is because of dirt, or corrosion from water ingress, or lubricant degradation. Not much point just adding lubricant without trying to clean it.

With one exception, if water has got in, washed out the oil or grease, and left rust residues, then adding oil and "working" the bearing may get it sufficiently functional for low tech applications like a wheelchair.

One of the things we warn fitters *not* to do is to spin up clean, dry bearings using a compressed air line prior to lubricating and fitting. You can cause enough surface damage that way to shorten the fatigue life. Drying the bearing with "canned air" or using an air line without spinning the bearing is OK. Should be using a filtered air line of course.