Crankshaft/connecting rod bearings in radial engines
Tue Sep 08, 2009 3:03 am
First of all, congrats to all of the participants in the FiFi project with the achievements so far. In my humble, layman, opinion, it is no less that impressive. 
I think this must be the place to get the little knowledge I have about radials 'aligned'?
[ As tech English is not the easiest English to handle, please excuse me, if I use the wrong technical term
]
As I understand it, the crankshaft/connecting rod bearings in the bigger WWII radial engines were/are plain bearings?
And there is a lubrication duct in the crankshaft, so that the lubricant always will enter under the 'loaded zone' of the connecting rod?
Is it possible to say anything about the load on that bearing? Must be huge? Guess that no lubricant results in an almost instant seizing up?
Take care
J
[Edit: Rephrasing]
I think this must be the place to get the little knowledge I have about radials 'aligned'?
[ As tech English is not the easiest English to handle, please excuse me, if I use the wrong technical term
]
As I understand it, the crankshaft/connecting rod bearings in the bigger WWII radial engines were/are plain bearings?
And there is a lubrication duct in the crankshaft, so that the lubricant always will enter under the 'loaded zone' of the connecting rod?
Is it possible to say anything about the load on that bearing? Must be huge? Guess that no lubricant results in an almost instant seizing up?
Take care
J
[Edit: Rephrasing]
Tue Sep 08, 2009 8:21 am
Yes the bearings are plain with about .002 inches of clearance. The oil film is enough to cushion the load. When there is a negative torque on the engine, the oil hole is not in alignment with the load. That causes the bearing material to rapidly wear away. A negative load on the engine is caused by a low power setting and the propeller attempting to turn the engine.
Thu Sep 10, 2009 2:55 am
The clearances run more like .004 to .008. Kinda why SAE 60 oil is used.
Thu Sep 10, 2009 5:27 pm
engguy wrote:The clearances run more like .004 to .008. Kinda why SAE 60 oil is used.
We use AeroShell 120
Thu Sep 10, 2009 7:08 pm
ZRX61 wrote:engguy wrote:The clearances run more like .004 to .008. Kinda why SAE 60 oil is used.
We use AeroShell 120
which is SAE 60
Thu Sep 10, 2009 8:32 pm
Matt Gunsch wrote:ZRX61 wrote:engguy wrote:The clearances run more like .004 to .008. Kinda why SAE 60 oil is used.
We use AeroShell 120
which is SAE 60
If it was actually 120, you'd have to chisel it out of the barrel
Re: Crankshaft/connecting rod bearings in radial engines
Fri Sep 11, 2009 2:35 am
Jesper wrote:First of all, congrats to all of the participants in the FiFi project with the achievements so far. In my humble, layman, opinion, it is no less that impressive.
I think this must be the place to get the little knowledge I have about radials 'aligned'?
[ As tech English is not the easiest English to handle, please excuse me, if I use the wrong technical term
As I understand it, the crankshaft/connecting rod bearings in the bigger WWII radial engines were/are plain bearings?
And there is a lubrication duct in the crankshaft, so that the lubricant always will enter under the 'loaded zone' of the connecting rod?
Is it possible to say anything about the load on that bearing? Must be huge? Guess that no lubricant results in an almost instant seizing up?
Take care
J
[Edit: Rephrasing]
Lube oil into any bearing is never into the loaded zone, its the no load area, and then it wedges into the loaded area. As pressure increases on the oil it increases viscosity, thus helping separate the surfaces better.