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Re: [TR] OD Testing

To: "Eureka Saws Co, Inc." <>,
Subject: Re: [TR] OD Testing
From: "Michael Marr" <>
Date: Sat, 4 Nov 2006 12:48:32 -0600
> OK, here's what we got. Switch lever up. (off) Start car, shift to 4th 
> gear.
> RPM's = 2000 (just +), speed is 40 mph. Holding the gas pedal constant and
> engaging switch lever (down), rpm's stay the same and the speed goes to 50
> mph. Switch lever back to up position speed drops back to 40 mph. Sounds
> like a wiring issue. Reversed but where? Switch is colored coded so can't 
> be
> there.

What you have described is exactly what should happen in the configuration 
you have described (i.e. constant engine speed, wheels in air with no 
resistance).  In this configuration, when OD is switched on, the rotating 
element with the greater moment of inertia will maintain its speed and the 
rotating element with tyhe lesser moment of interia will change its speed. 
If you look at the rotating masses and their moments in the 
engine/flywheel/geartrain pre O/D, vs the drive shaft, diff, half shafts and 
wheels, it makes sense that the engine speed will stay the same and the post 
O/D drivetrain will accelerate, particularly when the engine is under power. 
Somebody that remembers their machine design classes better than I can do 
the math!

Michael Marr
1960 TR3A
Plainfield, IL 

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