X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from nz-out-0506.google.com ([64.233.162.225] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTP id 2220178 for flyrotary@lancaironline.net; Mon, 30 Jul 2007 11:01:57 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.233.162.225; envelope-from=rwstracy@gmail.com Received: by nz-out-0506.google.com with SMTP id n29so870360nzf for ; Mon, 30 Jul 2007 08:01:18 -0700 (PDT) DKIM-Signature: a=rsa-sha1; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:sender:to:subject:in-reply-to:mime-version:content-type:references:x-google-sender-auth; b=eXZFPsYiZaM6B8c+BB75VIqzYYuA3WlJrDSZsJIzzSh22rXDvJuf3BYPz6nFQCxwxjwIKjRcKfH5yMXWK08xf/G9vfdGXCw+Gnnj3H+zS8sudIclPMfdPO28jk4urA7TRE0L6IuV3GjdwxH2TWL9JQYo1FD5rJA7U+UQUAqiS2s= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:sender:to:subject:in-reply-to:mime-version:content-type:references:x-google-sender-auth; b=QsHqLVlwOPN/DRJS7uKRof0Zk3j0vC6nQlsclGG3eqQqEeqfgobKQjkeb0+PnImkyV/Sk/QuYmnT/yq1uLFDoTuqrBpuon/lsphpRvIJwO7YRB+HH7OED2SCbor03bEIsAsF9CfXGdnG9QTPX7gMb0JlrPr1TQPjFCVtb+BRybw= Received: by 10.142.104.9 with SMTP id b9mr304981wfc.1185807677442; Mon, 30 Jul 2007 08:01:17 -0700 (PDT) Received: by 10.142.115.16 with HTTP; Mon, 30 Jul 2007 08:01:17 -0700 (PDT) Message-ID: <1b4b137c0707300801w5891e76bjb9f7389c4f8f7691@mail.gmail.com> Date: Mon, 30 Jul 2007 11:01:17 -0400 From: "Tracy Crook" Sender: rwstracy@gmail.com To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Gear mesh area? Was [FlyRotary] Re: Gear redrives.com In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_32689_24269169.1185807677397" References: X-Google-Sender-Auth: a915de232a06fc5e ------=_Part_32689_24269169.1185807677397 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline The formal definition of a spur gear is one that meshes in the same plane a= s the mating gear (as opposed to different planes, as in bevel, hypoid or worm gears). In this respect, straight cut gears and helical gears are both spur gears. It is the application of the gears that we are comparing, not whether they are straight or helical cut. That is indeed a different discussion. For the purposes of this discussion, I had assumed that "spur gear" meant the use of a single gear vs multiple gears (as in planetary) for the torque path. That is the slang that has been been generally accepted in the aviation community. Tracy On 7/29/07, Al Gietzen wrote: > > Caution; trying to claim 100% right on either end of the spectrum can be > equally wrong. > > > > Let's not mix up to two issues of spur gears vs helical; planetary vs > non-planetary. Note that most of those big WWII engines used planetary, = but > they used spur gears. Helical gear were developed and used primarily for = the > lack of noise. We don't like whining noises in our commercial vehicles. > Helical gearing has the disadvantage of significant axial loads which add > both stress and the friction. Contact area, even when computed correctly > (looking at how many teeth are in contact, and the area of contact on eac= h) > is only one factor in a more complex design process. > > > > Using a planetary for a compact, lightweight design is a good idea. We us= e > helical gears because they are readily available at a very reasonable > price. Using a custom designed spur gear planetary in our case could be = a > better approach, but at what cost? It could maybe eliminate some of the l= ost > power that goes into heating of the gears and oil =96 not much, but > something. When I disassembled my drive after about 40 hours, the only > evident wear was where the thrust bearing bears onto the mounting plate, = and > evidence of heat on the nylon snubber washers =96 the things that take th= e > axial loads from the helical gears. > > > > And I would think most gear designers would agree that using a lubricant > optimized to the gears could be better than using engine oil. But it > certainly adds complexity, and is it worth it? > > > > FWIW, just another point of view. > > > > Al > > > > > > > > > > -----Original Message----- > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] *O= n > Behalf Of *Ed Anderson > *Sent:* Saturday, July 28, 2007 5:27 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Gear mesh area? Was [FlyRotary] Re: Gear > redrives.com > > > > Thanks, Tracy > > > > Suspicions confirmed! It just seem a more sophisticated method of > transferring power from shaft to shaft than a Spur gear. But, as you > mentioned, as long as it is designed to me the loads, conditions and > environment, any number of methods of power transfer work, belts, gears, > hydraulic, turbine wheels, etc. However, for simplicity, weight and cost= , > its hard to beat a planetary gear set. Just my opinion of course. > > > > Ed > > ----- Original Message ----- > > *From:* Tracy Crook > > *To:* Rotary motors in aircraft > > *Sent:* Saturday, July 28, 2007 6:57 PM > > *Subject:* [FlyRotary] Re: Gear mesh area? Was [FlyRotary] Re: Gear > redrives.com > > > > Hi Ed, > > My quick & dirty answer is that the 6 pinion planet set is equivalent to = a > spur gear drive with a gear width totaling the width of all 6 planets. T= hat > would be: > > > > 6 * .785" =3D 4.71" Thats a mighty big & heavy spur gear! > > > > That's bigger than the one in a P-51 R.R. Merlin engine I think. Not an > apples to apples comparison due to the difference in bending strength of = the > tooth root but the biggie factor in power handling capability is indeed t= he > gear contact patch. > > > > Tracy > > > > On 7/28/07, *Ed Anderson* wrote: > > Well, Tracy, its sort of like flying 400 hours with a "Plugs Up" > installation - can't possibly work - the "experts" have said so {:>). > > > > It continues to amaze me (as it does you) how people can just accept > something sprouted out by some little (or unknown) self-styled expert > without attempt to ascertain whether there are any independent > sources/ facts supporting that position. > > > > As several individuals have pointed out most high powered (1500+) engines > of WWII had planetary gear boxes not to mention the dozens of different > turboprop engines. But, I guess all of that evidence does not out-weigh > the opinions of "experts". > > > > I have not done this but it would be interesting to calculate the teeth > mesh area of one of the spur gear PSRU and then compare it to the area of > the six pinion sun and planetary gear area engaged to transfer a similar > amount of power. I could be wrong, but my gut feel is that the sun and > planetary probably have more metal to metal contact area for transferring > power than the Sun gear. > > > > But, like I said - just a hunch, would be interesting to know. Anybody > have a quick answer?? > > > > > > > > Ed > > > > > > ----- Original Message ----- > > *From:* Tracy Crook > > *To:* Rotary motors in aircraft > > *Sent:* Saturday, July 28, 2007 1:47 PM > > *Subject:* [FlyRotary] Re: Gear redrives.com > > > > > Thought I'd see what else I was doing wrong so took a fresh look at the > geareddrives.com website. > > > > The kiss of death for a set of gears is in not using the proper* *lubrica= tion. > Separate lubrication systems are required for safety and for proper engin= e > and gear function. Sharing engine oil with the PSRU is asking for engine > and/or PSRU failure in advance. > > There is absolutely nothing I'm doing right! > > > > But the company does not look like it is for sale though. But Gershwinde= r > (Sp?) drive company is for sale now. Their chain drives were among the b= est > I've seen. > > > > Tracy > > > > ------=_Part_32689_24269169.1185807677397 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
The formal definition of a spur gear is one that meshes in the sa= me plane as the mating gear (as opposed to different planes,  as in be= vel, hypoid or worm gears).
 
In this respect, straight cut gears and helical gears are both spur ge= ars.  It is the application of the gears that we are comparing, n= ot whether they are straight or helical cut.  That is indeed a differe= nt discussion.
 
For the purposes of this discussion, I had assumed that "spu= r gear" meant the use of a single gear vs multiple gears (as in planet= ary) for the torque path.   That is the slang that has been = been generally accepted in the aviation community.
 
Tracy
 
 

 
On 7/29/07, = Al Gietzen <ALVentures@cox.net= > wrote:

Caution; trying to claim 100% r= ight on either end of the spectrum can be equally wrong.

 

Let's not mix up to two issues = of spur gears vs helical; planetary vs non-planetary.  Note that most = of those big WWII engines used planetary, but they used spur gears. Helical= gear were developed and used primarily for the lack of noise.  We don= 't like whining noises in our commercial vehicles.  Helical gearing ha= s the disadvantage of significant axial loads which add both stress and the= friction. Contact area, even when computed correctly (looking at how many = teeth are in contact, and the area of contact on each) is only one factor i= n a more complex design process.

 

Using a planetary for a compact= , lightweight design is a good idea. We use helical gears because they are = readily available at a very reasonable price.  Using a custom designed= spur gear planetary in our case could be a better approach, but at what co= st? It could maybe eliminate some of the lost power that goes into heating = of the gears and oil =96 not much, but something.  When I disassembled= my drive after about 40 hours, the only evident wear was where the thrust = bearing bears onto the mounting plate, and evidence of heat on the nylon sn= ubber washers =96 the things that take the axial loads from the helical gea= rs. =20

 

And I would think most gear des= igners would agree that using a lubricant optimized to the gears could be b= etter than using engine oil. But it certainly adds complexity, and is it wo= rth it?

 

FWIW, just another point of vie= w.

 

Al

 

 

 

 

-----Original = Message-----
From: Rotary motors in aircraft [mailto: flyrotary@lancaironline.net] On Be= half Of Ed Anderson
Sent= : Saturday, July 28, 2007 5:27 PM
To: <= /span> Rotary motors in aircraft=20


Subject: [FlyRotary] Re: Gear mesh a= rea? Was [FlyRotary] Re: Gear=20 redrives.com

<= span style=3D"FONT-SIZE: 12pt"> 

Thanks, Tracy

<= span style=3D"FONT-SIZE: 12pt"> 

Suspicions confirmed!  It jus= t seem a more sophisticated method of transferring power from shaft to shaf= t than a Spur gear.  But, as you mentioned, as long as it is designed = to me the loads, conditions and environment, any number of methods of power= transfer work, belts, gears, hydraulic, turbine wheels, etc.  However= , for simplicity, weight and cost, its hard to beat a planetary gear set. J= ust my opinion of course.

<= span style=3D"FONT-SIZE: 12pt"> 

Ed

----- Original Message -----

From: Tracy Crook

Sent:= Saturday, July 28, 2007 6:57 PM

Subject: [FlyRotary] Re: Gear mesh area? Was [FlyRotary] Re: Gear redrives.com

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt">Hi Ed,

<= span style=3D"FONT-SIZE: 12pt">My quick & dirty answer is that the 6 pi= nion planet set is equivalent to a spur gear drive with a gear width totali= ng the width of all 6 planets.  That would be:

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt">6 * .785" =3D 4.71"  &nb= sp; Thats a mighty big & heavy spur gear!  

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt">That's bigger than the one in a P-51 R.R= . Merlin engine I think.  Not an apples to apples comparison due to th= e difference in bending strength of the tooth root but the biggie fact= or in power handling capability is indeed the gear contact patch.=20

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt">Tracy

 

On 7/28/07, Ed Anderson < eanderson@carolina.rr.com> wrote:

 Well, Tracy, its sort of lik= e flying 400 hours with a "Plugs Up" installation - can't pos= sibly work - the "experts" have said so {:>).

<= span style=3D"FONT-SIZE: 12pt"> 

  It continues to amaze me (a= s it does you) how people can just accept something sprouted out by some li= ttle (or unknown)  self-styled expert without attempt to ascertain whe= ther there are  any independent sources/ facts supporting th= at position. =20

<= span style=3D"FONT-SIZE: 12pt"> 

As several individuals have pointe= d out most high powered (1500+) engines of WWII had planetary gear boxes no= t to mention the dozens of different  turboprop engines.  But, I = guess all of that evidence does not out-weigh the opinions of "experts= ". =20

<= span style=3D"FONT-SIZE: 12pt"> 

I have not done this but it would = be interesting to calculate the teeth mesh area of one of the spur gea= r PSRU and then compare it to the area of the six pinion sun and planetary = gear area engaged to transfer a similar amount of power.  I = could be wrong, but my gut feel is that the sun and planetary probably have= more metal to metal contact area for transferring power than the Sun gear.=  =20

<= span style=3D"FONT-SIZE: 12pt"> 

 But, like I said - just a hu= nch, would be interesting to know.  Anybody have a quick answer??

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt"> 

Ed

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt"> 

----- Original Message -----

Sent:= Saturday, July 28, 2007 1:47 PM

Subject: [FlyRotary] Re: Gear redrives.com

<= span style=3D"FONT-SIZE: 12pt">
 

<= span style=3D"FONT-SIZE: 12pt">Thought I'd see what else I was doing wr= ong so took a fresh look at the geareddrives.com website.

<= span style=3D"FONT-SIZE: 12pt"> 

The kiss of death = for a set of gears is in not using the proper lubrication. Separate lubrication systems are required for safe= ty and for proper engine and gear function. Sharing engine oil with the PSR= U is asking for engine and/or PSRU failure in advance.

There is absol= utely nothing I'm doing right!

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt">But the company does not look like it is for= sale though.  But Gershwinder (Sp?) drive company is for sale now.&nb= sp; Their chain drives were among the best I've seen. 

<= span style=3D"FONT-SIZE: 12pt"> 

<= span style=3D"FONT-SIZE: 12pt">Tracy

<= span style=3D"FONT-SIZE: 12pt"> 

=


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