Kasama T-Rex 700 Main Bearing Block

[duke666]

but I do know that this wish for thrust bearings on mains is a bit of a groundless fashion.

Agreed with that for a long time now.

Duke

[johnpotter82]

Originally Posted by SteamEngine

Some of this thread is evidently about main bearings and some of it about bearings in main grips.
I am just now building my TRex700E and decided to fit an extra main under the main gear to strengthen the frames by shunting bending load into the mast spindle. I am therefore inspecting the bearings as I write this post. The stock Align main bearings delivered with my kit are bog standard 6901z's clearly stamped on the shields. This is available from many makers and is a 'deep grove spindle bearing'. (The z means double shielded i.e.on both sides). 'Deep Grove' means that it is both a 'radial load' bearing component and- an 'axial load bearing component - in both directions. There is no need whatever for a thrust bearing to be fitted with it on this duty. Looking at the IINAA FAG catalogued on my shelf, the entry for their equivalent 12mm ID bearings gives the dynamic load capability as ~ 1,500 lbs at 20,000 rpm. Static load capability is roughly 45% of that.

The rated life is a big topic and depends on many things. Assuming a quality bearing, the rated life of a ball bearing in say a centrifuge (high speed low-ish load) will be in the 7-10,000 hrs region. If our bearings are falling apart it might be because the quality is not so good or that the bearings are subject to abuse. I think it might be a bit of both. You cannot use any old oil, it's got to be the proper stuff but my feeling is - leave it alone for the very short duty life expected of a heli. Don't swill with solvents and especially not nitro fuel or gas. If you want a super quality bearing from a reputable supplier - go buy one. They are not expensive, but don't abuse it. It should not run under misalignment and it should not be crashed into or exposed to dusty ground.

I don't have enough flight hours to notice that the bearings supplied with my kits are failing prematurely but I do know that this wish for thrust bearings on mains is a bit of a groundless fashion.

Are you saying that these main shaft bearings can handle one thousand 500 lbs of force pressing the wrong way at 20,000 rpms? Because I have trouble believing that. Maybe for like 1 second on the moon. According to you we really only need 1 main shaft bearing. And it should be good for like 50 years. Bearings wear out. Ive seen it. But hey a curve ball doesn't curve according to some people.

[Azalin]

Is this unit discontinued? I cant find it.