On 2/02/2015 6:54 PM, dbr wrote:
> Xeno wrote:
<snip>
>
>> Q3 If work is being performed, what is the result (output)?
>
> Think I covered that one
>
> I am amazed that a simple concept like differential gear set operation
> can again create so much argument. Torque may be what you are trying to
> determine but in a moving diff how can you not include the rotation if
> you are trying to work out the torque balance when cornering. Is it not
> this balance that goes to the heart of the original question.
I am not sure what the original question even was. I wasn't there, I
wasn't involved in any way in the discussion. With THIS thread, there
isn't even a QUESTION, just a statement. Anyone who has done higher
order learning (or research) would recognise it in an instant. It is
therefore up to, as Sylvia put it, the others to "have at it". I know
what she means, I know what she would expect to see as a "proof", I also
know I cannot provide that. There are a multitude of reasons for this
but prime amongst them is the fact that it's been a very long time since
I needed to delve into mechanical theory to any great depth. It was
certainly not required when teaching motor mechanic apprentices in
Victoria for the past 3 or 4 decades.
>
> With my very limited grasp on physics from my year 11 trade school
> education power as it relates to the diff operation is a combination of
> torque and rpm. The torque applied to the diff output axles is equal. As
> 1 wheel speeds up and the other slows to allow cornering the rpm of each
> axle changes. This will mean that a different amount of power is sent to
> the two axles but the torque will still be equal.
The level of understanding that you have is acceptable for a general
motor mechanic of today. When I was an apprentice, we used the earlier
versions of these 2 books or similar ones;
http://tinyurl.com/oyr3a8d
I recall some of the subjects we had to complete.
Motor mechanics theory I, II & III. Each of those was studied over a 1
year period. As well, we also had Motor mech calculations, motor mech
science and Technical drawing, again each subject being of a 1 year
duration. We didn't delve into the above books into great depth.
One of the requirements to get into trade teaching was, at least for the
automotive trade in Victoria, an "Automotive Technicians Certificate".
It wasn't mandatory to have it (I didn't possess it) but it was regarded
very favourably. The Technician's Certificate no longer exists but it
was initially begun at Richmond TAFE by the HOD at the time. It was seen
as filling a gap in the trade. It would have been the equivalent of what
is now the "Associate Diploma of Mechanical Engineering" but with much
more relevance to the automotive industry. Anyway, if you were studying
the Technicians Certificate, you would be delving into the above books
much more deeply. Most of the subjects in the Technicians Certificate
were much more advanced versions of the apprentice syllabus but there
were niceties like "Heat Engines I & II" and "Advanced Diesel". That's
where the engine dyno, the one Noddy says is a genset, came in very
useful as it involved determining the performance of an engine by
calculation, then testing the veracity of the calculations by testing
the engine on the dyno.
>
> I do know however this balance is affected by frictional forces
> within the diff. If you add some clutch packs behind the side gears you
> will end up with a limited slip diff and the statement of the torque
> being equal on both axles may no longer be true
>
> The other thing I have missed in this post is the apparent desire
> to ridicule others rather than understand the workings of the gear set
> in question. This is a game I in which I may have to surrender as I was
> never that good at it; But please do continue as it can be amusing at times
>
> Darren
>
What gets me are those who ridicule people with a higher order level of
comprehension than they themselves possess. I number among my long term
friends a number of engineers, some unfortunately deceased, and they
cover a range of disciplines; civil, mechanical, electrical and
electronic. Some of those engineers excel at the theoretical and the
practical, some just the theoretical. Regardless, I would never ridicule
them for their theoretical abilities. Rather, I respect them. In fact, I
envy them for their talent as I would have loved to have taken on
engineering myself. I did try but maths was my limitation. I seem to
have inherited my mother's "talent" for maths. Had I inherited my
father's maths abilities it might have been a different story.
--
Xeno.