Lewmar Old Generation Foot Blocks (Dual Sheave) - Lubrication Advise Required

[RunAgroundHard]

I have a pair of old Lewmar, dual sheave foot blocks. The sheaves are alloy, with stainless pin and needle bearings. When I dismantled them the needle bearings dropped out easily and are bone dry, no sign of lubrication. The foot blocks get a good dousing with seawater when pressed hard and of course rained on all the time in Scotland. There is no sign of wear but one of the sheaves was tight to rotate, but still rotated.

Were these needle bearings assembled dry, free of lubrication or would they have been lubricated originally?

The needle bearings and bushing when wiped with paper towel (dry wipe) leaves a slight grey smudge, which I assume is fine metal debris. I will be reassembling soon, hence can apply a smear of suitable lubricant, or nothing at all after a good clean up. I am inclined to apply a light touch of Lewmar or Harken winch grease, but fear this may just act as carrier to trap salt and wear products. What do you think?

The image of the sheave which looks scored, is in fact smooth and the rings are smeared and compacted dirt.

 

[Boathook]

I would think that they are ment to be dry. They don't get much use except when hoisting the sails and any oil or grease would attract dirt.
I've got a roller bearing block on my foredeck guiding the furling line and I just rinse it with freshwater every so often.

 

[vyv_cox]

It goes against all my experience to run roller bearings dry but this is not a very arduous duty. Perhaps a dry lubricant such as PTFE or silicone from an aerosol would avoid the possibility of dirt entrapment.

 

[RunAgroundHard]

They are used for the Genoa and staysail sheets. Rotation wise, not a lot of cycles, load wise bar tight 16mm genny sheets when hard in the wind.

I’ll clean up and reassemble dry but will check out the powder stuff. They are designed for the sheave to be easily released from the top after the pin is pulled out, so can be checked in future without a great deal of faffing about.

Appreciate the feedback back from all.

 

[Rappey]

Can bearinhs be run dry? A quote from smb bearings.

Technically yes. You can run bearings dry for slow moving applications such as tonearm bearings or clock bearings. However, if bearings are used without lubrication, we recommend that they are made of a corrosion resistant material such as stainless steel. Standard steel bearings may rust in the presence of moisture which is why they are coated with a thin, protective oil before being packaged.

For most uses, lubrication provides a vital thin film between contact areas to reduce friction, dissipate heat and inhibit corrosion on balls and raceway. If you don’t use a lubricant for high speed applications, this could result in a huge amount of heat build-up resulting in premature bearing failure.

That said, lubrication comes in all shapes and sizes, and it may not always look how you expect it to such as dry lubricants made from molybdenum disulphide or tungsten disulphide. This dry coating is burnished or sputtered onto the balls and raceways to give smooth operation and higher running speeds than unlubricated bearings.

 

[Blue Seas]

I have the larger versions of the same blocks (6" Dia iirc) - they have built-in grease nipples on top so they certainly can accept lubrication. They also have similarities with older Lewmar winches so again perhaps a bit of winch type grease (which has the advantage of staying in place) might be appropriate.

 

[Blue Seas]

Here is a 4" version