REM Polishing transmission gears and final drive?
REM Polishing transmission gears and final drive?
(OP)
Has anyone seen objective data re driveline loss reduction via the so-called "REM" micropolishing of transmission or final drive gears?
I've seen some claims that are kind of hard to believe, and wonder if anyone here has any actual data?
I'm rebuilding a fwd transaxle for road racing and considering this, but doubting that any really significant gains are to be had.
I can see durability gains from eliminating stress risers, but my power level is low enough that I don't foresee fatiguing the teeth. I can see possible significant reductions in a hypoid gearset, as I believe that that tooth pair type has significant sliding - but my R&P are simple helical gears.
Thanks in advance!
Al Seim
I've seen some claims that are kind of hard to believe, and wonder if anyone here has any actual data?
I'm rebuilding a fwd transaxle for road racing and considering this, but doubting that any really significant gains are to be had.
I can see durability gains from eliminating stress risers, but my power level is low enough that I don't foresee fatiguing the teeth. I can see possible significant reductions in a hypoid gearset, as I believe that that tooth pair type has significant sliding - but my R&P are simple helical gears.
Thanks in advance!
Al Seim





RE: REM Polishing transmission gears and final drive?
http://
http://ammtiac.alionscience.com/pdf/AMPQ7_1.pdf
RE: REM Polishing transmission gears and final drive?
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RE: REM Polishing transmission gears and final drive?
Thanks!
I've contacted REM for their tech info.
An obvious fear re the REM data is that, given the large scatter of automotive dyno results, it is so easy to "cherry pick" an outstanding result. And no marketing department worth its salt would fail to do so, at least to some extent!
It will be interesting to see what they have to say, and if they can cite any independent testing.
Skimming the papers referenced in your links - they look quite convincing on the subject of fatigue life, but barely touch on the subject of power loss. There is one mention of a known 30% reduction in frictional loss, which is intriguing. But I have no idea how significant the frictional loss is in a typical helical gear application. I think that it is significant in a hypoid gear.
(It is interesting that the authors of the paper attribute part of the fatigue life increase to friction reduction, not just to removal of stress risers.)
Anyway, thanks again.
Al Seim
RE: REM Polishing transmission gears and final drive?
RE: REM Polishing transmission gears and final drive?
It might be an improvement. But even if so, it is not likely to be one you can feel or point to. It is likely that your money and time would be better spent elsewhere.
RE: REM Polishing transmission gears and final drive?
SKF and FAG both predict "infinite" fatigue life in place of L10 calculated life for their ball and roller bearings below a certain contact stress >>IF<< some lubrication conditions can be met. One condition is that true ElastoHydroDynamic (EHD) operation be attained. One of the main requirements for EHD is sufficient lube viscosity for conditions.
Surface roughness undermines EHD (similar to hydroplaning) and would revert to the much shorter L10 predictions. Assignment or prediction of surface VS subsurface failures are not easy
RE: REM Polishing transmission gears and final drive?
As one of the folks working to implement this technology within the military helicopter community I can tell you "ISF'ing" your gears is the least inexpensive insurance policy you can buy. Navy data obtained two weeks ago shows used gears outperform new gears in terms of lower operating temperature, single tooth bending fatigue, pitting and scoring......all without any detrimental change in gear geometry. We are currently qualifying this for use on three exisiting aircraft and even the most pessimistic among our group have found NOTHING to complain or take exception with.
If you can find a cheaper, easier or less risky means by which to improve a gear...........let me know.......... because right now, ISF wins hands down!
RE: REM Polishing transmission gears and final drive?
Those among our group have found nothing to complain or take exception with.
RE: REM Polishing transmission gears and final drive?
RE: REM Polishing transmission gears and final drive?
RE: REM Polishing transmission gears and final drive?
RE: REM Polishing transmission gears and final drive?
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: REM Polishing transmission gears and final drive?
Dave
RE: REM Polishing transmission gears and final drive?
RE: REM Polishing transmission gears and final drive?
RE: REM Polishing transmission gears and final drive?
I would tend to question the comparing of a FWD transaxle to most other setups, especially with all but the final drive being planetary. Differences among things such as shock load, impact, lubrication, deflection, etc., are quite significant.
RE: REM Polishing transmission gears and final drive?
RE: REM Polishing transmission gears and final drive?
I'm convinced through reading that REM finishing does an excellent job in dramatically increasing fatigue life, and most probably significantly reduces loss in a typical hypoid (RWD) final drive.
What I'm not sure of is whether it would reduce loss measurably in an application like mine, ie all shallow angle parallel shaft helical gears, since friction loss is pretty small to start with.
Having said that, I've had several friends swear that they have seen ~2% gains on a chassis dyno using this. My problem is that I have trouble believing that chassis dynos, especially "casually used", repeat well enough to see a 2% gain - there are an awful lot of variables. A true transmission dyno would probably pick it up, but of course (??) the best test would be to use a transmission dyno but judge the results from trans temperature rise. But I've never heard of anyone doing that.
Al Seim
RE: REM Polishing transmission gears and final drive?
That's how Dana measure diff efficiency. I think there is an SAE paper on it
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: REM Polishing transmission gears and final drive?
RE: REM Polishing transmission gears and final drive?