The 3 planets are aligned with the marks in the same axis as each gears
center point such that the marks are exposed at the outer most edge of the
carrier. These teeth are relieved to allow easy installation. Nothing more.
dave
frogeye@porterscustom.com
Porter Customs 2909 Arno NE
Albuquerque, NM USA 87107
505-352-1378
1954 BN2 1959 AN5
Porter Custom Bicycles
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-----Original Message-----
From: healeys-bounces@autox.team.net [mailto:healeys-bounces@autox.team.net]
On Behalf Of Ed Woods
Sent: Monday, April 19, 2010 3:55 PM
To: healeys@autox.team.net
Subject: [Healeys] Fw: [TR] 'A' type overdrive question
>From a guru, Randall, on the Triumph List. Applicable to all Big Healeys
with overdrive.
Subject: Re: [TR] 'A' type overdrive question
>> The 3 gears on the planetary set are marked so that they are in a
>> specific
>> position relative to one another when the sunwheel is engaged.
>>
>> Why is this so? In other words, why is their position critical?
>
> I'm not sure I can explain this clearly, so bear with me.
>
> The number of teeth on the annulus is not a multiple of the number of
> teeth
> on the sun gear. Thus, if you draw an imaginary line from the center of
> rotation of the sunwheel, through the center of each planetary gear, it
> will
> hit both the sunwheel tooth and the annulus tooth in different positions.
> The two gears that are joined together to create each planetary gear are
> offset to match this "phase shift", but only in a certain position (since
> they also have different numbers of teeth).
>
> Some positions of the marks are simply impossible (the teeth won't mesh);
> but in some cases there is enough accumulated clearance to allow them to
> slide into engagement. That will pull the planetary carrier and sun gear
> off-center to some extent, leading to vibration in operation. It also
> causes most of the load to be carried by one planetary gear instead of
> evenly divided between 3 of them, so increased wear and even potentially
> tooth breakage could ensue.
>
>> If the gears were not marked for some reason, how could proper
>> alignment be determined?
>
> If the gears were not marked for some reason, I think I'd want to look for
> another set of gears. At any rate, I can't think of a guaranteed method
> of
> lining them up, short of cutting apart an annulus so the tooth engagement
> could be examined in situ. However, you might be able to do a setup
> without
> the housing, and check that everything is running on the same center,
> which
> _might_ be good enough.
>
> -- Randall
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