REFLECTOR: Franklin Accessory Gears

[John Dibble]

Larry,

Thanks for the comments.  All the gears have the numbers that look like 
they were hand written which I understand are found only on PZL parts, 
so I believe they are all PZL.  The coloration on both the alternator 
and fuel pump gears suggest that both were short by 1/16" from fully 
meshing with the drive gear.  The play between the driven gears and the 
housings are also about 1/16".  I plan to replace all with the American 
gears.

John

On 4/28/2012 5:47 PM, Laurence Coen wrote:
> John,
>
> That gear is what is known as a helical cut gear and should not 
> produce end thrust.  There was an AD issued for Franklin engines that 
> warned against using American made gears mating with PZL built gears 
> or visa-versa.  Since your gears need replacing that could be the real 
> problem.   The US built gears were made from cast iron blanks and the 
> PZL were steel.  They were also machined on different gear cutting 
> machines.
>
> Larry Coen
> N136LC
>
> --------------------------------------------------
> From: "John Dibble" <aminetech at bluefrog.com>
> Sent: Saturday, April 28, 2012 1:32 PM
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Subject: Re: REFLECTOR: Franklin Accessory Gears
>
>> On 4/28/2012 10:45 AM, Laurence Coen wrote:
>>> John,
>>>
>>> There shouldn't be wear between the gear and the housing under 
>>> normal circumstances.
>> Are you saying that the gear should not touch the housing?  Mine does 
>> and the bevel of the gear forces the gear against the housing making 
>> wear inevitable.
>>
>>>   Check for proper alignment of the alternator and the drive 
>>> pulley.  I think that bronze is the proper material to use for a 
>>> shim.  If the bronze wears down you have to replace the shim.  If 
>>> you use steel and the shim spins with the shaft the housing will 
>>> wear.  Replace the shim or replace the housing? Your choice.  Think 
>>> of the crank which is steel and is supported by soft bearing material.
>>
>> That's the other area I'm concerned about.  I'm hoping the metal 
>> analysis will indicate if the bearings are wearing.
>>>   Any wear that takes place is of the bearing not the crank.
>>>
>>> Larry Coen
>>> N136LC
>>>
>>> --------------------------------------------------
>>> From: "John Dibble" <aminetech at bluefrog.com>
>>> Sent: Friday, April 27, 2012 5:47 PM
>>> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>>> Subject: REFLECTOR: Franklin Accessory Gears
>>>
>>>> During my last oil change I got a big surprise, finding a lot of 
>>>> metal on my ADC oil filter screen.  This is a great filter and lets 
>>>> me see everything that's filtered from my oil. A magnet indicates 
>>>> that it is mostly steel.  There are shiny aluminum particles also.  
>>>> My Franklin mechanic told me that the gears are the most likely 
>>>> problem, so I have removed them.  A local mechanic told me that the 
>>>> gears need replacing. He checked the cam and that looks good.  I 
>>>> sent the metal from the filter for analysis so I can make a final 
>>>> determination if I need to look for any thing else.  I took apart 
>>>> the alternator gear and there is wear between the gear and the 
>>>> housing.  I want to install a shim washer between the gear and the 
>>>> housing.  Bronze was suggested, but after seeing the wear, I think 
>>>> bronze will get eaten up fast, so I'm thinking of mild steel.  Any 
>>>> comments or ideas will be appreciated.
>>>>
>>>> John
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>>
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> _______________________________________________
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