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Re: OD bench temperature measurements

To: 6pack@autox.team.net
Subject: Re: OD bench temperature measurements
From: Timothy Holbrook <tjh173@yahoo.com>
Date: Tue, 31 Jul 2001 10:04:59 -0700 (PDT)
Interesting data, but I'm a little confused on one point.  I thought
that the J type solenoid consumed LESS power than an A type.  Isn't
that why the A type requires a relay in it's circuits, and the J type
doesn't?  The A type takes more current, which a switch cannot handle,
and thus a relay is required.  The J type takes less current to
operate, and therefore needs no relay.  Therefore, since watts = volts
x amps, and voltage is constant (around 12-14 volts produced by
alternator), the higher current A type solenoid should consume more
watts.  Right?  Am I missing something here?

Tim Holbrook
1971 TR6 


--- Nelson  Riedel <nriedel@nextek.net> wrote:
> While testing a J type OD we noticed it seemed to get hotter than the
> A type we
> had tested earlier so we set up a comparison test as follows:  We ran
> both units
> in a test stand at ~2600 RPM output (~54 mph) in high gear with OD
> engaged.
> Near the end of the run we elevated the gearbox front for two minutes
> at a 12
> degree angle, then did the same to the back and then let run level
> for a few
> minutes.  This was to mix the oil from the front and back in an
> attempt to
> equalize the temperature of the oil. We then measured the temperature
> of the oil
> in the gearbox.
> 
> The oil temperate in both units was 138 degrees F.   The fact that
> the
> temperature in both gearboxes rose to the same final temperature is a
> coincidence.  The ambient temperature was a few degrees warmer (~80
> vs. 75) when
> the A Type was tested because we had the widow open to disperse the
> fumes from
> curing powder coating.   There were probably a half dozen other
> parameters that
> affected the results so all that we can say is that the temperature
> rise is
> similar, a little over 1 degree F per mph.  There are all kinds of
> other effects
> when the gearbox is in operation carrying a load.  For example, the
> surrounding
> temperature is much higher  because of engine & exhaust heat, there
> is much
> better ventilation when one is going down the road at  60 mph, the
> bearing load
> is higher when transferring power through the gearbox/OD, etc. 
> However, FT's
> earlier observation that his A type was hot enough to fry an egg is
> probably a
> typical temperature --- 100 degrees ambient in VA, and going 100 MPH
> -- that
> makes it about 212 degrees F, could boil water on it.
> 
> We also found the J type solenoid seemed hotter than the A type so we
> computed
> the power for each:
>     A type solenoid consumed 12 watts
>      J type  solenoid consumed 21 watts
> This explained why the J type solenoid was much hotter.
> 
> Nelson Riedel
> Granville, OH
> 76 TR6 - J OD (repairing damage from fender bender)
> 68 TR250 - A OD  (next project - new paint)
> 70 TR6 - A OD (all the parts in a pile ready to assemble)
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