Black FP Transmission Gears

Hey Cd,

I was looking for the specs on the gears that inside the “2009 Black FP KOP Transmission”. I don’t have access to the shop till next week, but a local team needed some plates machined out because their banebot planetaries finally kicked the bucket. All the gears were grinded and worn out, very kewl to see. I just needed the teeth count and the DP/module of each gear.

Thanks,

-RC

If you can wait until Tuesday evening and want to PM me an email address, I can send you a picture of the gears and you can count teeth. I’ll also measure the OD of each gear and you can work backwards to the rest. Unfortunately, that’s about the best I can do for you.

Ivan

I would love that.

Thank you,

-RC

RC,

Here are the ODs of the gears and the tooth counts. As far as I acn tell, all of the gears in the FPs are the same regardless of color. The motor pinion may change. In the 2009 KoP I think the motor pinion had 16 teeth. The other option is 19 teeth. I don’t have a 16 to measure, but the 19 tooth one measures .673" OD.

            Large OD            Count	                Small OD      Count

Gear #1 2.283” 72 teeth .870” 25 teeth
Gear #2 2.510” 79 teeth .919” 19 teeth
Gear #3 2.634” 62 teeth 1.300” 12 teeth
Gear #4 3.501” 38 teeth

Hope this helps,

Ivan

I’m pretty sure the FP gears are .8 Mod. (Based on my recollection that stock FP pinions are 31.75 DP, aka ~32 DP. Knowing DP = 25.4/Mod you can solve and get .8 Mod)

Pitch Diameter (mm) is Mod x Toothcount.

So, for the 72T gear.

PD (mm) = 72 * .8 = 57.6 mm

PD (in) = 57.6 mm x (1 in / 25.4 mm) = 2.268 in (although I imagine it’d be more accurate to just enter the metric units into SW)

I know you already know how to get C-C distances, so that should cover it for you.

Thank you Ivan and Adam, big help there. Now I can get to CAD’ing that gearbox.

-RC

Adam is probably right about the .8 mod but that would only be correct for the pinion and the first 2 plastic gears. Second to third is a larger tooth and third to fourth is larger yet.

Here are some approximate CC distances measured from the one in my basement:

Motor to #1 1.375” approximately
#1 to #2 1.630” measured across the idler shafts and subtracted .375”
#2 to #3 1.707” also measured across the shafts.
#3 to #4 2.247” approximately because there isn’t much to measure to on the last gear.

Ivan

1and2.jpg
3and4.jpg


1and2.jpg
3and4.jpg

Ivan is totally right, I’m an idiot. Of course the Mod would increase as the reductions do.

I guess set up some formulas to get an approximate mod based on those C-C, then round the Mod to the nearest actual (it should be pretty darn close), then calc a precise C-C from that.