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tony ennis
10-28-2007, 05:01 PM
How do these work? Are they actually for oil, not grease? They seem to be a zirc fitting with a reservoir.

rkepler
10-28-2007, 05:27 PM
I've seen a couple designs, the only real cup one I've seen expects that you'll fill the cup with grease and thread it onto the fitting, screwing the cup in pushes grease into the bearing. I've not seen that with a zerk, usually with a zerk you pressure in the grease from the gun, the zerk closes the fill hole behind you (note that zerks are also used on many mills for way oil, so before filling be sure that they want grease and what kind).

tony ennis
10-28-2007, 05:30 PM
The image is just out of focus enough...

http://i10.ebayimg.com/08/i/000/be/c0/b2b2_1.JPG

If that isn't a zirc, does the grease get drawn in by suction or something? Seems a tad unlikely...

rkepler
10-28-2007, 05:44 PM
Looks like the type I never saw - screw it partway on, fill the cup through the zerk. When you want a bit more grease in just screw it in a little bit and it'll push some in. It might be that someone added the zerk sometime later so they could just hit it with a gun.

BadDog
10-28-2007, 06:04 PM
I would guess it's really just a reservoir. Grease, as we think of it, is really more just the "soap" (or similar) structure for holding the lube till it's required. So all that nice "grease", packed into a hub around bearings, or in that cup, is just hanging out, waiting for the lube in the bearing (or whatever) to start to run shy, which heats it up, which releases the oils trapped in the thickening agent, which then cools. That forms a sort of self balancing system and explains part of why there are so many greases. It's also why you rake out the old "cake", which has lost all it's lube, and replace with fresh when repacking hubs/spindles/etc. And why you generally add more than just what fits in the bearings (depending on what it is). That extra grease generally never finds it's way into the bearings, but will release it's lube if things start to heat up a bit.

That's my limited understanding anyway. There are engineers here that can likely do a much better job of explaining...

wierdscience
10-28-2007, 08:29 PM
It's just a newer way of filling the cups,before you had to unscrew the cap completely,pack in some grease by hand and then screw the cap back on.Time consuming and messy.

These you just inscrew a few turns,pump with grease and move on.

kendall
10-29-2007, 12:52 AM
had grease fittings on one of my old lathes that were zerk fitted, filling them compressed a spring like 'bearing buddies' on trailer wheels, were pretty nice. Unlike bearing buddies they had a rod that stuck out and showed how much grease was actually in them, check lube at a glance.

appeared to be very good shop builds, looked but haven't found any commercial versions.

agree, those caps look like someone wanted to avoid hand packing the caps, or prefered a periodic shot with the grease gun.

Ken.

Tinkerer
10-29-2007, 01:46 AM
How do these work? Are they actually for oil, not grease? They seem to be a zirc fitting with a reservoir.
That looks like the pic from ebay. I can say they work great and are for grease. Sure makes maintaining the counter shaft on my atlas lathe a breeze been using them for a couple years now. You can either direct pressure lube or back off and fill. Hated hand packing the old ones with these on it's a fast and clean operation. :)