Lotus Elan

4th Gear semantics

PostPost by: "Elton E. (Tony) Cla » Tue Feb 07, 2006 5:33 pm



> The Van Doorne (DAF) trasmission has been used in small Ford and
> Fiat cars. The torque of an Audi might be too much for it though.


Huge harvesting machines; combines and such, used the "shifting-sheave"
variable speed belt drive systems from the early fifties until being
supplanted by hydrostatic variable speed drives in relatively recent
years. There are a jillion snowmobiles, carts and lawn-tractors which use
the belt variable drive as well.
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PostPost by: mikecauser » Tue Feb 07, 2006 6:40 pm

On Tue, 7 Feb 2006 11:58:14 -0500 "Robert D. LaMoreaux" <***@***.***> wrote:

Then of course there used to be a car with a variable speed tranmission that
had not belts or gears. They used a spinning disk and a wheel would press
against the disk to transmit force with the speed being a function of how
far from the center of the disk the wheel was. I can't remember what car or
other details, but it was something from the teens or twenties.

Austin in the 1930s. The transmission was patented by Charles Hunt in
1877, further developed by Frank Hayes in the 1920s, and then again as
Perbury or Perbury-Hayes in the 1960s. Although it was never made to
last long in cars it apparently is still made for aircraft applications.

http://www.histomobile.com/histomob/tech/2/83.htm


Mike
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PostPost by: "Roger Sieling" » Tue Feb 07, 2006 6:40 pm

Rob,

Very, Very early International Harvester trucks had this feature, or more shall we say motorized wagons. That's also how it changed directions. Dead center was neutral, over center was reverse and could theoretically go as fast in rev as forward.

Roger

>> ***@***.*** 2/7/2006 11:58 AM >>>
As far as ratio, the ratio is between the speed of the input shaft
and the speed of the output shaft. After all, if you look at an old
Daf (anyone remember that car) transmission, there were no gears at
all, with the ratio changes due to the varying sizes of two pulleys
and a belt. I believe this is also used on some recent Audi
transmissions!


Ford started making CVTs last year for the Ford 500, Ford Freestyle, and
Mercury versions of those cars. These are large cars with 200bhp V6s and FWD
or AWD and they are 3600-4500lbs. There are other CVTs in use, but these are
currently the largest production cars that I know of with them. Of course
the modern belts are metal not rubber.

Then of course there used to be a car with a variable speed tranmission that
had not belts or gears. They used a spinning disk and a wheel would press
against the disk to transmit force with the speed being a function of how
far from the center of the disk the wheel was. I can't remember what car or
other details, but it was something from the teens or twenties.

Rob LaMoreaux

A & D Technology Inc.
4622 Runway Blvd.
Ann Arbor, MI 48108
734-822-9696
Fax 734-973-1103
Main Desk 734-973-1111
www.mtspt.com
Work email: ***@***.***
Home email: ***@***.***
"Roger Sieling"
 

PostPost by: TYPE45 at aol.com » Tue Feb 07, 2006 7:23 pm

In a message dated 2/7/06 11:05:09 AM, ***@***.***es:

<< They used a spinning disk and a wheel would press
against the disk to transmit force with the speed being a function of how
far from the center of the disk the wheel was. >>

This is similar to the transmission design common in snow blowers. The two
disks are perpendicular to each other and are infinitely adjustable, limited
only by the number of notches the manufacturer puts on the shift gate. Mine has
three possible positions, thus it's a 3 speed which is plenty. I've seen as
many as 7 notches on other models which is nothing but a marketing tool.
Unfortunately, my snow blower averages more engine hours per year than my Elan
does. On the other hand, due in part to automatic decompression, it always
starts on the first pull. I guess that makes me the human Super Starter!

Frank Howard
'71 Elan S4 SE (4 speed + reverse)
"84 Honda HS55 Snow Blower (3 speed + reverse)
Minnesota
TYPE45 at aol.com
 

PostPost by: elansprint71 » Tue Feb 07, 2006 8:17 pm

Rich,
If you have plenty of time look at this variable transmission- I'm not
sure that it has been used in a car but I have (many, many tears ago)
serviced them in industrial applications:

http://www.allspeeds.co.uk/kopp.html

Enjoy!

Pete.


Richard Boyd wrote:

Thanks for the responses to my 4th gear rambling. Just stirring up
symantic trouble.

Bill,
Yes. Too much free time. Where did I put the car wax.

Mike,
Now I know: roost, not battery. I'll use gallery instead of artery, etc.
I like your suggestion: use "speed" (vitesse) instead of "gear." 4th
speed from now on.

Tim,
Your description of a Hydramatic sounds really interesting. Looking
into the shifting vane position will consume some of that excess free
time that Bill says I have.

Art,
Gotta disagree: shifting into 4th speed does indeed couple the input
shaft to the output shaft. No power goes through any gear set.
Two-shaft transmissions (motorcycles, some transaxles, etc.) can't do
this, but most (all?) three-shaft transmissions employ this direct
drive system. BMW had a direct drive 5th speed, even though the shift
knob moves forward to select 5th. BMW has a bell crank inside the
trans to reverse shift lever direction (at bottom of lever) so that
the synchro can slide forward for 5th.
Yes, 1:1 is a ratio. But a ratio between what two things? Not a ratio
between two gears (or any combination of gears); not in 4th. That was
my point.

Rich Boyd

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PostPost by: richboyd » Wed Feb 08, 2006 6:34 am

I like the wide variety of responses. Let me propose my original
question again, but in the context of CVT transmissions. What is
ratio? What does "gear" mean?
In a CVT, you certainly have a continuum* of ratios, but do the
ratios refer to shaft speeds (angular velocity), or to "gear ratios"?
Are there "gears" in a CVT? You have to love a car that is called a
Dafodill (I really appreciate the DAF history contributions. Thank you).

What contsitutes a "gear ratio?" Does 4th speed in an Elan qualify
for a "gear?" Does a CVT have gear ratios? Or just transmission
ratios? Or shaft ratios?

Rich Boyd

*other than continuum, only vacuum has the remants of U-U instead of
the modern joining of U's : W.
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PostPost by: c.beijersbergen » Wed Feb 08, 2006 9:56 am

Hello Richard,

You wrote:
'I like the wide variety of responses. Let me propose my original
question again, but in the context of CVT transmissions. What is
ratio? What does "gear" mean?
In a CVT, you certainly have a continuum* of ratios, but do the
ratios refer to shaft speeds (angular velocity), or to "gear ratios"?
Are there "gears" in a CVT? You have to love a car that is called a
Dafodill (I really appreciate the DAF history contributions. Thank you).

What contsitutes a "gear ratio?" Does 4th speed in an Elan qualify
for a "gear?" Does a CVT have gear ratios? Or just transmission
ratios? Or shaft ratios?

Rich Boyd'



A transmission has as sole function to mate the characteristics of a power producer (in a car: engine) to the chracteristics of a power consumer (in a car: driven wheels). The characteristics consist of the relation between rotation speed and torque. The transmission can have fixed ratios of speed and torque between ingoing and outgoing shafts or it can have a variable ratio. Transmissions with fixed ratios are gearboxes (with gears with teeth), toothed belt systems and chain systems. In all these solutions the speed ratios are directly related to the ratios between number of teeth on the active gears, the number of teeth on toothed belt wheels and on the relation of the teeth on the chain sprockets. But essential for the function of a transmission is the speed ratio.
In a CVT the variable part of the speed ratio is not done by gear wheels, but mostly by friction on cone shaped surfaces. So CVT's do not have 'gear ratios' that are of any significance but the have speed ratios that are within a band of usable numbers. Sometimes they only a limited number of values is being used so the CVT behaves like a manual box, sometimes all values are being used where behaviour really becomes continious.

BTW, I do have the impression that this semantic question only exists in english. In german 4th gear is '4en Gang', which means something like fourth speed ratio, in dutch it is 'vierde versnelling' where 'versnelling' has the reverse meaning of 'speed reduction' and in french it is '4eme vitesse' as mentioned before by someone.
Is there any other language that knows words like gearbox or fourth gear?


DAF made a terrible marketing error at the introduction of its line of small cars that all had the variable belt drive. The did put al lot of empasis on the fact that these cars were very well suited to elderly or invalid people. So nobody that considered himself or herself to be young and healthy was pepared to be seen near any of these DAF's. It became even worse when one of the models was called Daffodil. Only young students who discovered how fast the cars could be driven once one mastered the required driving style could be seen racing in the streets.
The bad image was the reason for DAF to become active in racing (F3) and rallying. DAF never managed to produce more than 100.000 cars a year.

But now for a semantic contribution. If the term 'fourth gear' is not right because no gears are being used, is then 'third gear' not also wrong, because it is not one gear thast is being used, but at least two? Should the term 'gear' here not been seen seperated from its technical form, but only in its function, like the german 'Gang'?



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