F4i Gear Material

[Adam J.]

Does anyone know what type of steel and/or treatments is/are used in manufacturing the gears in the F4i transmission.

Furthermore, does anyone know where I can find mechanical properties of these gears. I could just use the ASME database, but if the gears have some sort of special treatment, finding mechanical properties in the ASME database could be difficult; it might just be easier if someone knew of a source where they had this information directly.

Also, does anyone know where I can find information about the load ratings and fatigue life of the bearings in the transmission?

I need this information for a project due next week, so any info would be much appreciated.

Thanks,

--Family Guy

[Adam J.]

Does anyone know what type of steel and/or treatments is/are used in manufacturing the gears in the F4i transmission.

Furthermore, does anyone know where I can find mechanical properties of these gears. I could just use the ASME database, but if the gears have some sort of special treatment, finding mechanical properties in the ASME database could be difficult; it might just be easier if someone knew of a source where they had this information directly.

Also, does anyone know where I can find information about the load ratings and fatigue life of the bearings in the transmission?

I need this information for a project due next week, so any info would be much appreciated.

Thanks,

--Family Guy

[Pennyman]

Gears can be made from a lot of different materials. 4140, 4340, 8620 can be used but a any medium carbon, hardenable steel can also be used.

The heat treatment process is not trivial and depends on the type of material, the load applied and the properties you want out of it.

From what I saw of the f4i transmissions laying around the shop, I would say that they were made of a deep-hardening steel because the load was being applied to fairly small cross sections. However, the thickness of the gears aren't that big to begin with. Dimensional stability is also important with gears, so a steel that distorts very little (or is quenched in air or some other slower-cooling medium) is probably likely. I'm pretty sure some sort of surface hardening was used after tempering as well to increase the wear properties too.

The ASM handbook volume 4 is a great resource on heat treatment.

In terms of bearings, they were deep groove ball bearings with 6-10 balls per bearing and ID's of around 25mm. You can look up equivalent load ratings on SKF or Timken if you want.

Don't take my word for it though, these were just observations I made from looking at the dismantled F4i's in the shop.

Hope this helps.

[Drew Price]

I don't think anyone is going to have that specific information, in my experience the OEM's will:

1) Be extremely protective of such information,

2) Not use commercially available materials and processes for something so specialized, they will have developed their own stuff for it.

For any project I did at school, if you assume reasonable things for the material, treatment, pitch circle, fatigue life, etc., you will fine for any questions the prof. will have.

Best,
Drew

[Demon Of Speed]

To find the chemical composition (which is only part of the story) you can use an arc-spectrometer. Most schools should have one.

Most Gears are also Case hardened and/or carbarised. This gives a good wear surface, and allow the gear to not be to brittle. There are multiple ways to determine the after treatment. A general hardness testing (testing a part inside the gear at lease 0.1 in) will give some idea of the heat treatment used (and strength of the material, kind of). A Micro-hardness test will show if any surface treatment has been done. Additionally, looking a a test specimen under a microscope some help you determine the structure of the material. Some of the test are destructive, so use a broken/warn-out gear.

There is a chance that not all the gear are the same. I would guess same base material, but different after treatment. 1st gear takes a lot more abuse than 5th.