advice or help - now how torque converters etc work

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John
| Regarding the auto V the manual, what is the torque converter
| for and why does the auto have one and not the manual box.
| I would also like to know why the Auto box has different
| fluid in it compared to the manual.
You can think of a torque converter as being like two propellers facing
one another inside a bath of stiff oil. One propeller is connected to
the engine and the other to the gearbox, and when the engine turns it
rotates its propeller, which rotates the oil, which in turn rotates the
propeller connected to the gearbox.
The advantage of the system is that any difference in speed between
engine and gearbox is taken up smoothly by the oil being stirred,
effectively achieving what slipping the clutch in a manual box does; the
disadvantage is that stirring things dissipates energy in them causing
lower efficiency (=3D higher fuel consumption) and also heating - which is
why a hard-working auto box needs an extra oil cooler.
It's called a "torque converter" because its real shape allows rotation
speed to be traded off for torque. In effect the engine can spin fast at
relatively low torque, and the gearbox can be driven slowly at higher
torque. This is why most auto-box LC users only need to use low range
very occasionally, whereas we manual box folk make rather more use of
it. Also why auto gearboxes tend to have fewer gear ratios than manual
boxes.
Torque conversion is good for starting and acceleration, but not so good
for cruising at constant speed, so in cars the actual shape is a
compromise between the ideal for torque conversion and the ideal for
simple transmission of rotation. There is also a "lock up" that
effectively forces both sides to rotate at the same speed.
| Are the gears different between the two or is there another reason.
Identical in concept, but different in layout. Autos tend to use
"planetary" gearboxes where a central "sun" wheel has "planet" wheels
spinning around it. The advantage of this system is that to change gear
all you have to do is to lock up or free the rotation of different
"planet" wheels, which can be achieved by a series of clutches.
This suits the automatic system since the clutches can be hydraulically
or electronically controlled, and no gear levers have to be stirred
around. The old Sturmey Archer 3 speed gears on bicycles work this way
- think how easy they are to use.
.=2E. Which about sums up the sum total of my knowledge about auto boxes!
Christopher Bell
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Hey Christopher
Thanks for that easy to understand explanation. I can now visualise it. So
am I right in thinking the speed of the engine rotates this fly wheel which
in turn rotates the same at the gear box, which in turn changes the gears in
the box.
So the more the engine rotates its wheel the more the gear box rotates its
wheel and so the gears either change up or down. Ah its so easy, think ill
go strip it down now just to see.
If all that fluid is trapped in the torque why did Toy not have a drain plug
to get it out, after all that would make sense would it not.
John C
92HDJ 80 1HDT Rep of Ireland
 
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John
| Thanks for that easy to understand explanation. I can now
| visualise it. So am I right in thinking the speed of the
| engine rotates this fly wheel which in turn rotates the same
| at the gear box, which in turn changes the gears in the box.
| So the more the engine rotates its wheel the more the gear
| box rotates its wheel and so the gears either change up or
| down. Ah its so easy, think ill go strip it down now just to see.
| If all that fluid is trapped in the torque why did Toy not
| have a drain plug to get it out, after all that would make
| sense would it not.
You'll probably find a working diagram of it all online if you look hard
enough, which might be a tad easier than stripping the gearbox down.
Drain plug? From what I can make out changing the fluid in an auto box
is NOT a simple "drain and refill" operation - refer to our automatic
colleagues for a method if you plan to try - which might explain the
absence of this.
I've seen many anguished posts from the US over the years along the
lines of "I decided to change my auto fluid, so I took out 10 quarts,
can only get 8 back in, and now the truck won't move - help!"
If it ain't broke, don't fix it! I'd find out (Colour? Smell? Old age?)
whether your auto fluid needs changing before worrying about it. The
Haynes manual says every two years, but I find it hard to believe that
is really necessary unless you have been absolutely hammering it.
CB
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I change my ATF every three months or thereabouts. A simple drain and
refill.
Don't know or care whether that's overkill but it's neither a hard nor
time consuming job so long as you don't try to flush the whole lot out.
Pete
Christopher Bell wrote:
SNIP
 
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On 1/3/06, Peter Browning <[Email address removed]> wrote:
 
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I've heard about this auto box 'lock up' before and I don't quite
fathom it. How does it work? Is it possible to lock it manually?, or
does it please itself? Thanks.
Regards, Clive.
 
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Clive wrote:
| I've heard about this auto box 'lock up' before and I don't
| quite fathom it. How does it work? Is it possible to lock it
| manually?, or does it please itself? Thanks.
|
Have a look at http://tinyurl.com/863vj which is quite a good
description of torque converters generally, and lock-up in particular
(on page 2). Broadly when there is enough oil pressure the input and
output impellors are locked together by friction, pretty much like the
clutch in a manual gearbox.
Maybe there is a cruiser variant with a manual lock-up switch, but I
haven't seen one.
Peter wrote:
out.
Clearly you've got it all worked out - tell John how!
CB
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