Is hyraulic drive posible?

Isn't this country wonderful. I've been here since nine and I can
really appreciate it.

Bryan "The Monk" Chaisone

ChuckSlusarczyk wrote in message ...
In article , Richard Riley says...


:That's my dad's quote. He told me there is no limit to what a man can
:do. I'm from Thailand, but I tell my employees (mostly latinos) the
:same thing, "Este es Estados Unidos, todos es possible".

HA! A latino friend of mine says the same thing to his (all latino)
employees - but he says "Este es *United States,* totos es possible."

My Polish Grandfather ...in fact everybody in the Polish ghetto where I grew up
used to say "we're in America now learn to talk english". That's why everything
was possible,we all learned english as the common language and we all became
Americans. Not so anymore.

Chuck( I never saw a voting ballot in Polish)S

Andy Asberry wrote:
Maybe you can answer a question I've had for sometime. What is the
relative efficiency of hydraulics, belts, gears and chain drive?
You've given the hydraulic answer. Care to take a stab at the others,
please?

Andy,
One thing to keep in mind with every power transmission apparatus is:
Every watt of power that goes into it comes out either as power at the
working end, or heat somewhere along the way. So the more heat the
apparatus sheds (as a percentage of input power), the less efficient it is.

Russell Kent

GeorgeB wrote in message . ..
On Thu, 08 Jul 2004 02:52:48 GMT, Andy Asberry
wrote:

I design and provide technical support for electrohydraulic systems
for a living, and this is not a place that I owuld recommend their
use.

George

Maybe you can answer a question I've had for sometime. What is the
relative efficiency of hydraulics, belts, gears and chain drive?
You've given the hydraulic answer. Care to take a stab at the others,
please?

STAB, yes ... feelings based on things I have seen and heard ... NO
HARD FACTS to back this up. (I looked and failed to find support)

hydraulics TOTAL ... ~80%
v belt, 90-95%
tooth belt, 92-97%
spur/bevel gear, 96-98%
worm gear, 25-80%
chain. 96-98%

lesser ratios (nearer 1:1) are more efficient.

Based on what I recall from my mechanical engineering days
spur gears will be the most efficient. This is because
spur gear teeth have a curvature called an involute which
permits rolling contact between the tooth surfaces. Still,
I think 95% is about the best you get with spur gears, I
wonder if I can still find my old texts...

Bevel gears have some sliding contact between the teeth and
so more friction less efficiency than spur gears. But they
have more surface in contact between meshing teath so they
can handle larger loads for their size. Typical worm drives
with a small worm and a large worm gear for a large speed
reduction and large torque gain will be the least efficient,
down around 5%, IIRC.

V-belts are probably the trickiest to optimize. Too little
tension and energy is lost in slippage, too much and energy
is lost in elastic deformation of the belt. Cog belts allow
you to reduce the tension on the belt without slippage.

The other drive mechanisms tend to have their highest efficiency
with a slightly 'sloppy fit' that minimizes elastic deformation
but also introduces other problems like backlash, vibration and
so on.

--

FF

(Harry K) wrote in message . com...

I am much of a lurker here but...It seems to me that a lot of the
naysayers are missing the point that you are proposing to drive -two-
props with -one- motor. There should be at least a break even if not
a savings in weight over -two- motors driving two props. I like
considering off the wall projects and have attempted a few myself,
mostly failures.


Actually, I'd charaterize it as driving two props with three motors.
Two hydraulic motors direct driving the props and one motor driving
the hydraulics.

I think a mechanical drive, like the chain drive the Wright Bros used,
would be more efficient.

--

FF

Fred the Red Shirt wrote:

GeorgeB wrote in message . ..

On Thu, 08 Jul 2004 02:52:48 GMT, Andy Asberry
wrote:


I design and provide technical support for electrohydraulic systems
for a living, and this is not a place that I owuld recommend their
use.

George

Maybe you can answer a question I've had for sometime. What is the
relative efficiency of hydraulics, belts, gears and chain drive?
You've given the hydraulic answer. Care to take a stab at the others,
please?

STAB, yes ... feelings based on things I have seen and heard ... NO
HARD FACTS to back this up. (I looked and failed to find support)

hydraulics TOTAL ... ~80%
v belt, 90-95%
tooth belt, 92-97%
spur/bevel gear, 96-98%
worm gear, 25-80%
chain. 96-98%

lesser ratios (nearer 1:1) are more efficient.


Based on what I recall from my mechanical engineering days
spur gears will be the most efficient. This is because
spur gear teeth have a curvature called an involute which
permits rolling contact between the tooth surfaces. Still,
I think 95% is about the best you get with spur gears, I
wonder if I can still find my old texts...

Bevel gears have some sliding contact between the teeth and
so more friction less efficiency than spur gears. But they
have more surface in contact between meshing teath so they
can handle larger loads for their size. Typical worm drives
with a small worm and a large worm gear for a large speed
reduction and large torque gain will be the least efficient,
down around 5%, IIRC.

You are saying that 95% of the power is lost in the gear set? I find
that really hard to believe. If you put 100 HP in and lost 95HP in the
gears, that amount of heat would likely melt them down in short order.


Matt

On Thu, 08 Jul 2004 14:38:45 -0400, GeorgeB wrote:

On Thu, 08 Jul 2004 02:52:48 GMT, Andy Asberry
wrote:

I design and provide technical support for electrohydraulic systems
for a living, and this is not a place that I owuld recommend their
use.

George

Maybe you can answer a question I've had for sometime. What is the
relative efficiency of hydraulics, belts, gears and chain drive?
You've given the hydraulic answer. Care to take a stab at the others,
please?

STAB, yes ... feelings based on things I have seen and heard ... NO
HARD FACTS to back this up. (I looked and failed to find support)

hydraulics TOTAL ... ~80%
v belt, 90-95%
tooth belt, 92-97%
spur/bevel gear, 96-98%
worm gear, 25-80%
chain. 96-98%

lesser ratios (nearer 1:1) are more efficient.
Thanks.

Matt Whiting wrote in message ...

Typical worm drives
with a small worm and a large worm gear for a large speed
reduction and large torque gain will be the least efficient,
down around 5%, IIRC.

You are saying that 95% of the power is lost in the gear set? I find
that really hard to believe. If you put 100 HP in and lost 95HP in the
gears, that amount of heat would likely melt them down in short order.


Yes, it would. I suggest that you avoid worm drives for transmissions
that handle 100 hp continuous duty. Worm drives are used where you
need a huge torque increase and can afford a huge power loss better
than you can afford the space complexity and expense of a planetary
gearbox or a battery (Damn it's late at night what do you call these?)
of spur gears.

Typical worm drives are very low speed, or have a very short duty
cycle. In most of the systems I have seen the worm only turns
at a fraction of an rpm in continuous duty (IIRC 1/15 rpm is common
for the worm in a telescope clock drive with a worm wheel with 96 teeth).
When slewing the telescope they may turn several rpm but only for
a minute or so. If those worms were run continuously at a few
hundred rpm they would certainly coke out the grease in a couple
of minutes.

There are some big-assed worm drives that do things like rotate the
turrets on cranes fairly quickly but they operate intermittently
and that HUGE worm wheel soaks up and dissipates a lot of heat.

I am less than 100% certain of the 5% figure, but will stick by it for
now.

--

FF

"Russell Kent" wrote in message ...
Andy Asberry wrote:
Maybe you can answer a question I've had for sometime. What is the
relative efficiency of hydraulics, belts, gears and chain drive?
You've given the hydraulic answer. Care to take a stab at the others,
please?

Andy,
One thing to keep in mind with every power transmission apparatus is:
Every watt of power that goes into it comes out either as power at the
working end, or heat somewhere along the way. So the more heat the
apparatus sheds (as a percentage of input power), the less efficient it is.


Tis true of all devices which is why all electrical resistance heaters
have the same efficiency--the 'waste' heat is indistinguishible from
the 'product' heat.

--

FF

Matt Whiting wrote in message ...
Fred the Red Shirt wrote:

GeorgeB wrote in message . ..

On Thu, 08 Jul 2004 02:52:48 GMT, Andy Asberry
wrote:


I design and provide technical support for electrohydraulic systems
for a living, and this is not a place that I owuld recommend their
use.

George

Maybe you can answer a question I've had for sometime. What is the
relative efficiency of hydraulics, belts, gears and chain drive?
You've given the hydraulic answer. Care to take a stab at the others,
please?

STAB, yes ... feelings based on things I have seen and heard ... NO
HARD FACTS to back this up. (I looked and failed to find support)

hydraulics TOTAL ... ~80%
v belt, 90-95%
tooth belt, 92-97%
spur/bevel gear, 96-98%
worm gear, 25-80%
chain. 96-98%

lesser ratios (nearer 1:1) are more efficient.


Based on what I recall from my mechanical engineering days
spur gears will be the most efficient. This is because
spur gear teeth have a curvature called an involute which
permits rolling contact between the tooth surfaces. Still,
I think 95% is about the best you get with spur gears, I
wonder if I can still find my old texts...

Bevel gears have some sliding contact between the teeth and
so more friction less efficiency than spur gears. But they
have more surface in contact between meshing teath so they
can handle larger loads for their size. Typical worm drives
with a small worm and a large worm gear for a large speed
reduction and large torque gain will be the least efficient,
down around 5%, IIRC.

You are saying that 95% of the power is lost in the gear set? I find
that really hard to believe. If you put 100 HP in and lost 95HP in the
gears, that amount of heat would likely melt them down in short order.


Matt

Ah, here's a page that compares some worm drives to geared
transmissions, the highest they show is for a measely 60:1
speed reduction. But t looks like a 96:1 worm drive would
typically be not a lot better than 50% efficient. So it seems
I was off by about a factor of 10 - 12 on the efficiency, but
only a factor of 2 on the waste heat so you still better not
run 100 hp through one it unless it is actively cooled or uses
huge gears.

http://www.falkcorp.com/tech-info/wormgear.asp

Not something you'd use to drive a propeller, in any case.

--

FF