X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [64.12.137.3] (HELO imo-m22.mail.aol.com) by logan.com (CommuniGate Pro SMTP 5.2.0) with ESMTP id 2786320 for flyrotary@lancaironline.net; Tue, 11 Mar 2008 00:48:55 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.3; envelope-from=Lehanover@aol.com Received: from Lehanover@aol.com by imo-m22.mx.aol.com (mail_out_v38_r9.3.) id q.c04.2febbdee (14502) for ; Tue, 11 Mar 2008 00:48:14 -0400 (EDT) From: Lehanover@aol.com Message-ID: Date: Tue, 11 Mar 2008 00:48:14 EDT Subject: Re: [FlyRotary] Thrust on E-shaft To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1205210894" X-Mailer: Unknown sub 36 X-Spam-Flag: NO -------------------------------1205210894 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit If the taper is part of a fastening system and the isolators are not free to move on the taper, it seems unlikely that it will generate thrust and load the engines crank shaft. In any case, make sure the freeplay of the engine crank shaft is available to measure with a magnetic base dial indicator. Loosen the belts. Set up the indicator on the adaptor plate, and place the dial shaft in parallel with the crank. You may have to clamp a bit of material the flex plate to get a target for the dial. Gently pry the front pulley forward with a pry bar or big screw driver. Then set the dial to zero. Pry the flywheel (flex plate) in the opposite direction (gently) and look at the indicator. You should have the same measurement as when the engine was assembled. .0015" to .0035". If it requires that you pry a bit harder in one direction over the other to get your reading, or you need only pry in one direction to get the measurement, then the assembly is preloaded as it sits and requires modification to adjust away that preload. Be very careful doing this, as the thrust plate is more flexible than some folks imagine. Typically one side or the other of the drive system would run on a set of splines that would accommodate the depth of installation and allow the freeplay to center up in operation. A very small amount of antisieze compound will keep the splined section working. The exact same thinking as the splines in the clutch disc center on the car. If the tapered pins just engage holes in the pucks and the pucks are free to move on the pins, then it is likely that a mild thrust load will be imparted to the crankshaft. So, because of the taper, when the engine imparts torque into the isolators they will try to slide off of the pins and generate a small amount of thrust. If the pins are free to move, inside the isolators, but are not tapered, then it is unlikely there is a problem. The engine crank should be free to move in the above amount. It would not hurt to check the crank freeplay on a regular basis. Very closely in the first few hours of operation. Loosen the belts, grab the front pulley and shove it back and forth. You will be able to feel the movement with a bit of practice. Once a record of good performance is established just make it a phase dock check or annual, or 100 hour, whatever you do inspection wise. The thrust preload problem would be a problem with any auto engine installation. The thrust bearings in car engines are very small and cannot share any of the propeller loads or a constant load for any length of time. It would not be just a rotary problem. Lynn E. Hanover In a message dated 3/10/2008 10:00:04 P.M. Eastern Daylight Time, downing.j@sbcglobal.net writes: Lynn, I have a Marcotte Redrive and the drive disc has 5 pins that appear to have a taper similar to a Morse Taper and the driven disc has isolator bushings, which are internally tapered to fit the pins, of some type to absorb the torsional vibrations. Will this setup cause an undesirable load on the thrust bearings. I was hoping to get a first start when the snow goes, now this question comes up. JohnD **************It's Tax Time! Get tips, forms, and advice on AOL Money & Finance. (http://money.aol.com/tax?NCID=aolprf00030000000001) -------------------------------1205210894 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
If the taper is part of a fastening system and the isolators are not fr= ee=20 to move on the taper, it seems unlikely that it will generate thrust and loa= d=20 the engines crank shaft. In any case, make sure the freeplay of the engine c= rank=20 shaft is available to measure with a magnetic base dial indicator. Loosen th= e=20 belts. Set up the indicator on the adaptor plate, and place the dial shaft i= n=20 parallel with the crank. You may have to clamp a bit of material the flex pl= ate=20 to get a target for the dial. Gently pry the front pulley forward with a pry= bar=20 or big screw driver. Then set the dial to zero. Pry the flywheel (flex=20 plate) in the opposite direction (gently) and look at the indicator. Yo= u=20 should have the same measurement as when the engine was assembled. .0015" to= =20 .0035".
 
If it requires that you pry a bit harder in one direction over the othe= r to=20 get your reading, or you need only pry in one direction to get the measureme= nt,=20 then the assembly is preloaded as it sits and requires modification to adjus= t=20 away that preload. Be very careful doing this, as the thrust plate is m= ore=20 flexible than some folks imagine.
 
 Typically one side or the other of the drive system would ru= n on=20 a set of splines that would accommodate the depth of installation and allow=20= the=20 freeplay to center up in operation. A very small amount of antisieze compoun= d=20 will keep the splined section working. The exact same thinking as the spline= s in=20 the clutch disc center on the car.
 
If the tapered pins just engage holes in the pucks and the pucks a= re=20 free to move on the pins, then it is likely that a mild thrust load will be=20 imparted to the crankshaft. So, because of the taper, when the engine=20 imparts torque into the isolators they will try to slide off of the pins and= =20 generate a small amount of thrust. 
 
If the pins are free to move, inside the isolators, but are not tapered= ,=20 then it is unlikely there is a problem. The engine crank should be free to m= ove=20 in the above amount. It would not hurt to check the crank freeplay on a regu= lar=20 basis.  Very closely  in the first few hours of operation. Loosen=20= the=20 belts, grab the front pulley and shove it back and forth. You will be able t= o=20 feel the movement with a bit of practice. Once a record of good performance=20= is=20 established just make it a phase dock check or annual, or 100 hour, whatever= you=20 do inspection wise.
 
The thrust preload problem would be a problem with any auto engine= =20 installation. The thrust bearings in car engines are very small and cannot=20 share any of the propeller loads or a constant load for any length of t= ime.=20 It would not be just a rotary problem. 
 
Lynn E. Hanover
 
 
 
In a message dated 3/10/2008 10:00:04 P.M. Eastern Daylight Time,=20 downing.j@sbcglobal.net writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Lynn, I have a Marcotte Redrive and the d= rive=20 disc has 5 pins that appear to have a taper similar to a Morse Taper and t= he=20 driven disc has isolator bushings, which are internally tapered to fit the= =20 pins, of some type to absorb the torsional vibrations.  Will this set= up=20 cause an undesirable load on the thrust bearings.  I was hoping to ge= t a=20 first start when the snow goes, now this question comes up. =20 JohnD



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