Why thrust bearing direction

[Tripler]

Just assembled my new Titan and wondered why, with the blade grips on the spindle
does the large internal diameter part of the thrust bearing have to go to, or as I read it, against the main rotor hub??
I thought it would be the other way round to give the blades a bit of movement,,
Anyone know why

[Steve]

Dunno why, but it's the same on the Millennium.

I suppose the head dampers offer a certain controlled amount of resistance to flex, but if there is to be any flex during flight, then the slightly larger inner diameter forces the flex from both blades to be concentrated at equi-distant points from the centre of rotation on the feathering spindle.

[Raptorite]

The larger of the two diameter holes in the thrust plate goes to the outside, the smaller one closest to the head. If you think about it, as the feathering spindle moves it will move least closest to the head and more further from the head.

Cheers,
Pete.

[Tripler]

That makes sense,Raptorite,,but then so does the Managers reply

The Manual say's,,

Large internal diameter always go toward the main rotor hub,,

does "toward" mean face toward or agains't the head?

depends how you read it,
I can see I'm going to have to strip it down again and check

[Tripler]

Anyone else have a theory.

[Steve]

Copied from the pdf Millennium manual.....

Note:
Be sure to keep to the sequence
shown when fitting the axial bearings
(S1551). Axial bearing disc with large
I.D. on the inside; axial bearing disc
with small I.D. on the outside.

[gazza]

Every heli I've ever owned with thrust races the Larger I.D race has always gone nearest the hub

I think it's to allow a small amount of pivot to work in conjunction with the dampeners...Although I'm probably wrong as me and theories dont mix

[Jamez]

I think it's to prevent the inner thrust plate from touching the spindle as this would negate the effect of the bearing, the idea being that the all the load then passes through the bearing, where as if the inner thrust plate was to touch the spindle, the load would pass through that instead.

Think that sound's about right

[Ade_Law]

spot on Jamez. The part of the bearing that touches the blade grip must not touch the spindle or it effectively locks the bearing.

Ade