Improving efficiency

Ray Heindl said:

Parker-Hannifin is running a competition among college students to
design a hydraulic drivetrain for bikes that's more efficient than
chain drive. "The challenge is to make the bike more efficient using
improved power transmission and energy recovery..."

<http://tinyurl.com/5q32l> Feel free to lie about where you're
located.

Excerpt:
"A hydraulic system has potential for capturing and storing energy as
the bike goes downhill. The pump forces the fluid into a chamber called
an accumulator that later is released to provide a burst of power in
going uphill."

I'm thinking about a different kind of BURST of power one might get.

Don't think I'm gonna wanna ride one of these.

Mark Janeba

Per Mark Janeba:

Quoted message said:

Excerpt:
"A hydraulic system has potential for capturing and storing energy as
the bike goes downhill. The pump forces the fluid into a chamber called
an accumulator that later is released to provide a burst of power in
going uphill."

Wasn't this the stuff of an April Fool's joke in one of the bike mags some years
back?
--
PeteCresswell

Mark Janeba said:

Ray Heindl said:

Parker-Hannifin is running a competition among college students to
design a hydraulic drivetrain for bikes that's more efficient than
chain drive. "The challenge is to make the bike more efficient using
improved power transmission and energy recovery..."

<http://tinyurl.com/5q32l> Feel free to lie about where you're
located.

Excerpt:
"A hydraulic system has potential for capturing and storing energy as
the bike goes downhill. The pump forces the fluid into a chamber called
an accumulator that later is released to provide a burst of power in
going uphill."

I'm thinking about a different kind of BURST of power one might get.

Don't think I'm gonna wanna ride one of these.

Mark Janeba

Dear Mark,

Actually, accumulators are quite safe, though a tad
heavy--look into the hydraulic ram pump invented by
MontFogelir--er, Montgolfier.

http://science.howstuffworks.com/question318.htm

Regrettably, I can't find the site with the really elegant
picture of a j-bend pipe with a cannon-ball that makes the
operation of these impossibly simple pumps clear even to me.

Joe Montgolfier

Accumulators are a mature 'technology' at much higher power levels than
appropriate to bicycles. If there is a hazard then it is due to the
particular design.

I don't intend to visit the site but their project specifications will be
interesting if they really expect to improve on the chain/cog system. For
instance, the below, "power transmission and energy recovery..."

"Mark Janeba" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Ray Heindl said:

Parker-Hannifin is running a competition among college students to design
a hydraulic drivetrain for bikes that's more efficient than chain drive.
"The challenge is to make the bike more efficient using improved power
transmission and energy recovery..."

<http://tinyurl.com/5q32l> Feel free to lie about where you're located.

Excerpt:
"A hydraulic system has potential for capturing and storing energy as the
bike goes downhill. The pump forces the fluid into a chamber called an
accumulator that later is released to provide a burst of power in going
uphill."

I'm thinking about a different kind of BURST of power one might get.

Don't think I'm gonna wanna ride one of these.

Mark Janeba

Quoted message said:

Mark Janeba said:

Ray Heindl said:

Parker-Hannifin is running a competition among college students to
design a hydraulic drivetrain for bikes ...

Excerpt:
"A hydraulic system has potential for capturing and storing energy as
the bike goes downhill. The pump forces the fluid into a chamber called
an accumulator that later is released to provide a burst of power in
going uphill."

I'm thinking about a different kind of BURST of power one might get.

Don't think I'm gonna wanna ride one of these.

Dear Mark,

Actually, accumulators are quite safe, though a tad
heavy...

I'm trying to imagine one that is **light enough** to be practical on a
bicycle - it still adds up to BOOM!, at least IMHO.

Side note to "Junkyard Wars" viewers - did you ever notice how the
hydraulic designs almost always lose - not because hydraulics are
inherently a bad idea, there's just some things they weren't meant for -
I think bikes and bodge jobs go in this category.

Mark Janeba

Mark Janeba said:

Quoted message said:

Mark Janeba said:

Ray Heindl wrote:

>Parker-Hannifin is running a competition among college students to
>design a hydraulic drivetrain for bikes ...

Excerpt:
"A hydraulic system has potential for capturing and storing energy as
the bike goes downhill. The pump forces the fluid into a chamber called
an accumulator that later is released to provide a burst of power in
going uphill."

I'm thinking about a different kind of BURST of power one might get.

Don't think I'm gonna wanna ride one of these.

Dear Mark,

Actually, accumulators are quite safe, though a tad
heavy...

I'm trying to imagine one that is **light enough** to be practical on a
bicycle - it still adds up to BOOM!, at least IMHO.

Side note to "Junkyard Wars" viewers - did you ever notice how the
hydraulic designs almost always lose - not because hydraulics are
inherently a bad idea, there's just some things they weren't meant for -
I think bikes and bodge jobs go in this category.

Mark Janeba

Dear Mark,

If you're going to try to drag this hydraulic bicycle drive
train thread off into the weeds of "practical," then I for
one refuse to pursue it!

Indignantly,

Carl Fogel

Per Mark Janeba:

Quoted message said:

Side note to "Junkyard Wars" viewers - did you ever notice how the
hydraulic designs almost always lose - not because hydraulics are
inherently a bad idea, there's just some things they weren't meant for -

Can anybody offer a ballpark figure for hydraulic drive efficiency vs gear?

It always seemed to me like the ideal multi-use walkbehind garden tractor would
be hydraulic drive and hydraulic PTO...

Drive bc brakes/power could be integrated into a single handgrip for each wheel
(as belt systems are today...)

PTO bc it would enable separating the accessory-joining mechanism from the PTO
power transfer mechanism - enabling a vastly simpler more trouble-free docking
system.

But nobody's doing that - and my first thought is that hydraulic systems just
soak up too many horsepower for small applications.
--
PeteCresswell

On Mon, 24 Jan 2005 00:47:41 GMT, "(Pete Cresswell)" <[email hidden]>

Quoted message said:

Per Mark Janeba:

Quoted message said:

Side note to "Junkyard Wars" viewers - did you ever notice how the
hydraulic designs almost always lose - not because hydraulics are
inherently a bad idea, there's just some things they weren't meant for -

Can anybody offer a ballpark figure for hydraulic drive efficiency vs gear?

It always seemed to me like the ideal multi-use walkbehind garden tractor would
be hydraulic drive and hydraulic PTO...

Drive bc brakes/power could be integrated into a single handgrip for each wheel
(as belt systems are today...)

PTO bc it would enable separating the accessory-joining mechanism from the PTO
power transfer mechanism - enabling a vastly simpler more trouble-free docking
system.

But nobody's doing that - and my first thought is that hydraulic systems just
soak up too many horsepower for small applications.

Dear Pete,

While this page is probably discussing engines much larger
than bicycles (40 horsepower), it finds 60-85% overall
efficiency for hydraulic drives (see section 4.3):

http://www.omax.com/drive_pump.html

Derailleur-style bicycle chains have been tested at 90% to
95% efficiency:

http://www.ihpva.org/pubs/HP52.pdf

Carl Fogel

Mark Janeba said:

Quoted message said:

Mark Janeba said:

Ray Heindl wrote:

>Parker-Hannifin is running a competition among college students to
>design a hydraulic drivetrain for bikes ...

Excerpt:
"A hydraulic system has potential for capturing and storing energy as
the bike goes downhill. The pump forces the fluid into a chamber called
an accumulator that later is released to provide a burst of power in
going uphill."

I'm thinking about a different kind of BURST of power one might get.

Don't think I'm gonna wanna ride one of these.

Dear Mark,

Actually, accumulators are quite safe, though a tad
heavy...

I'm trying to imagine one that is **light enough** to be practical on a
bicycle - it still adds up to BOOM!, at least IMHO.

Side note to "Junkyard Wars" viewers - did you ever notice how the
hydraulic designs almost always lose - not because hydraulics are
inherently a bad idea, there's just some things they weren't meant for -
I think bikes and bodge jobs go in this category.

I also notice that the junkyard teams using pneumatics and hydraulics always get
fresh plumbing, fitments and nubbins.

Ron

"Ray Heindl" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Parker-Hannifin is running a competition among college students to
design a hydraulic drivetrain for bikes that's more efficient than
chain drive. "The challenge is to make the bike more efficient using
improved power transmission and energy recovery..."

Ray, thankfully for the contestants I did not see anything in the article
about having to surpass the efficiency of a chain and sprocket drive system
in order to win this competition. This is all about teaching college
students the design to prototype development process for low power hydraulic
systems which employ energy recovery. It is not about shaping the future of
the Tour de France.

Dave