[Diy_efi] measurement of tailshaft Twist

[Bill Washington]

Gents,
    A couple of questions:
    1. How would you compensate for vertical and horizontal movement of 
the tailshaft (due to engine movement) relative to the sensors? While it 
may be small I believe it could generate much larger phase errors than 
the signal that you are trying to measure.
    2. This method is only (possibly) suitable for rear wheel drive 
vehicles with an exposed tailshaft - I do not see how it could be 
implemented of front wheel drives (and even 4WDs where the torque is 
split between two - front and rear -  driveshafts) or vehicles with 
enclosed tailshafts (torque tubes).

    Thoughts???

Regards
Bill


>
>-----Original Message-----
>From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
>Behalf Of niche at iinet.net.au
>Sent: Wednesday, April 20, 2005 8:03 AM
>To: diy_efi at diy-efi.org
>Subject: [Diy_efi] RE: [offlist] Strain gauge on engine mounts
>
>
>At 07:51 AM 20/04/05, you wrote:
>  
>
>>Not sure that is such a good idea Mike ... the rubber is non
>>linear ... just like the mounts would be, and resolving the
>>edges requires some very fast counters at high speed and
>>quite big counters at low speed ... plus who wants that much
>>slop in the drivetrain ... it's not like you can swap this
>>thing in and out all that easily is it?
>>    
>>
>
>Interesting point, think I misread this initially too, way too
>many mailboxes here...
>
>I think it should be possible to do this without any rubber,
>and avoid any drivetrain slop and be fully differential
>in respect of drivetrain lateral or even axial motion... !
>
>I mean, consider this:-
>
>a.   Toothed ring gear (pitch to be determined) on tail shaft
>      close as possible to universal joint, firmly attached
>
>b.   Second toothed ring gear as above but at furthest other
>     end so max length of tailshaft between gears
>
>c.   Tailshaft balanced appropriately
>
>Question arises, would there be enough twist of the tailshaft
>over the most appropriate length for the dynamic range of
>torque measurement needed ?
>
>ie. At lowest extreme the tailshaft twist may be so low that
>there wont be much discernible phase shift for a coarse
>pitch ring gear.
>At highest extreme it may well skip a cycle if too fine pitch,
>so a sync method would be needed if one is interested in
>wide dynamic range - which obviously is fairly easy to implement...
>
>Any mech structural engineers here care to estimate degrees
>of twist for say 100 newton metres of torque over length of say
>650mm and 80mm dia... ?
>
>
>  
>
>>Regards from
>>
>>
>>Mike Massen
>>Perth, Western Australia
>>VL Commodore Fuse Rail that wont warp or melt !
>>http://niche.iinet.net.au
>>    
>>
>  
>
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