bearing materials for planet gears
bearing materials for planet gears
(OP)
Under high loads soft materials can distort enough to allow some missalinement, what are some good materials to use for bushings/bearings to support these gears? Also differential gears could be grouped into this too.





RE: bearing materials for planet gears
Cheers
I don't know anything but the people that do.
RE: bearing materials for planet gears
If you're using a journal or plain bearing, as opposed to a rolling element bearing, and you have high radial loads, do everything you can to ensure the bearing operates in a hydrodynamic condition. The bearing substrate should be a material that has adequate fatigue strength, and it should have a thin overlay of a softer material to provide embedability of debris.
If, as you say, there is excessive deflections of the journal, then the bearing will edge load and fail. Regardless of what bearing material you use.
RE: bearing materials for planet gears
RE: bearing materials for planet gears
All surfaces must be ground to size and super-finished beyond the quality that a normal machine shop could achieve.
Single digit microns make the difference between life and death in these parts. Some manufacturers will even sort components to optimize fit. Others size the loose rollers vs. the bore so that they will lock securely in the gear until the pin is inserted. Still other choose to use needles mounted in a cage - reducing life but improving speed and friction performance.
What I mean by this is to support Matt51 - in a modern automatic transmission don't go messing with this stuff unless you REALLY know what you are doing. Use OEM parts.
RE: bearing materials for planet gears
I reread your question and I remember a failure (not mine) of a PSRU. It was the planet carrier for a Ford C6. It seems the (3) planet carrier is a cheap aluminum casting, and after reading tbuelna's post I wonder if that is what caused the failure in deforming under load to edge load the needle bearing.
I have used OEM from an Allison trans before as it was close to the load and speed requirements that I needed at the time.
Also a side note is the gear vendors will offer different grade of gears. I use between 7 and 10 as budget allows.
Cheers
I don't know anything but the people that do.