bearings within a gas turbine.

[ronnie barker]

Hi guys,
I am trying to remember the qualities of diferent types of bearings within the gas turbine engine. i.e. roller, taper and ball. I know one is used where there is axial play. Can anyone help?

[minigundiplomat]

Roller, ball, roller, roller, ball.

[maxtork]

Ball bearings can carry radial as well as axial loads. Roller bearings typically are not used for axial loads but can carry more load radially than a ball bearing as they have a larger contact area. Taper bearings are like roller bearings but they can support axial loads usually in one direction.

Pretty general descriptions and not always a hard and fast rule but that should get you started.

Max

[HeliComparator]

... therefore due to the large temperature variations (and therefore thermal expansion) within a shaft of a turbine engine, typically one bearing is a ball bearing which takes radial loads and also locates the shaft axially in both directions, absorbing the thrust loads, whilst the other(s) is a (are) roller bearing, taking the radial loads but allowing for movement of the shaft due to thermal expansion.

I don't think that taper roller bearings are used much - they can absorb radial and axial loads but they can only absorb the radial loads if there is lots of axial load - might be OK whilst the engine is producing lots of power but no good on shutdown etc.

I think that is an expanded version of what minigundiplomat was saying!

HC

[Thud_and_Blunder]

Nah, it was just the Gnome groundschool mantra.:ok:

[[email protected]]

And some of us are still chanting it:ok:

[minigundiplomat]

Sad isnt it! I could probably use that space for something useful these days.

[riff_raff]

ronnie barker,

Each shaft assy in a turbine engine uses some combination of ball and cylindrical roller bearings. One end of the shaft (usually the compressor/fan end) uses a ball bearing (usually a gothic arch or 4-point configuration) for radial and axial loads. The opposite end of the shaft uses a cylindrical roller for radial loads. This combination of ball and roller bearings provides the correct degree of constraints on the shaft system. The ball bearing controls axial location at the front, while the roller bearing at the rear allows for thermal expansion and contraction along the engine's length.

Tapered rollers are not used on turbine engine spools since they do not like operating at high DN values, due to the high friction losses created where the roller big end rubs against the race shoulders.

Sometimes the ball and roller bearings used in turbine engine spools employ oil film damping of the outer races to help mitigate some of the detrimental dynamic loading effects the bearing might experience.

Hope that helps.
riff raff

[12Watt Tim]

Don't worry, minigun, I haven't flown a helicopter in ten years and I still remember that one!