Hello, I have a few questions about the bearing greases article:
I don't understand the format of the DIM label. This image illustrates my confusion:
View attachment 128
Where is Mark 2?
Secondly, what does "infrequent access" and "narrow clearances" mean in Table 6, comparing the different solid state lubes?
Thank you for your hard work to crease and maintain such a detailed guide.
Hi Luke,
Very good questions. That's not clearly explained in the tables.
Please let me know if these explanations clarifiy the dilemmas, so that I can add the info to the article (I've already updated the DIN section it with a brief explanation and a link to this discussion).
DIN marks
Mark "2" is used only if a grease has some of the extra qualities listed in that column.
For example, Molybdenum disulphide grease has the solid MoS2 particles, so its DIN mark would contain the letter "F" from the "Mark 2" column, and a typical MoS2 grease's DIN mark would look like this:
DIN KF 2 N-25
Unlike the "Mark 2a," "Mark 2" is obligatory to use and note, if the grease has any of those properties.
Edit:
The low temperature value ("-25") is also not listed in the table, but it is a realistic value for the given grease type and intended application.
"Infrequent access" and "narrow clearances"
"Infrequent access" refers to places where cleaning and re-greasing regularly is not practical (not affordable or not possible). Some things cost time or money, and generally, the cost of lubrication should not exceed the cost of parts (rough, generalization that is often true and taken into account for maintenance procedures).
Motorcycle suspension linkage pivots are probably a decent (though not perfect) example.
"Narrow clearances" refers to space between two materials whose interface is lubricated. Ball bearings usually have a negative clearance (i.e. preload, they are not loose in the least), but they are rolling and get re-lubricated as they roll (though bicycle headset bearings on a fast descend is a good example of ball bearings not turning nearly enough to get re-lubricated as the vibrations displace the lubricant).
Some other assemblies though do have some (positive) clearance. That clearance can be very tight, very narrow, approaching zero (but not quite). Think various linkages and rods.
Relja
P.S.
For any readers coming here from Google, this is the article we are talking about:
"
Bicycle bearing greases – explained"