I have a customer that among other things, rewinds obsolete air coil
electric motors. He has asked me about building a dyno so he can test
motors to something other than 'yep, it turns' under power.

Looking through SIC I only find one article on building a dyno. It looks
to be a fair bit of work. As he called me while on the road today and
the connection was bad, we couldn't really get into details. I am unsure
what HP and torque the motors develop, though it's not a lot. I also
don't know what rpm range he wants to test.
Did a bit of Googling and didn't find a whole lot on small model engine
sized dyno building.

Anyone know about web resources for different approaches?


Thanks,

Jon Anderson

Jon

I recently built a dyno for testing 3 phase motors. It'll probably
handle 10 HP. It uses a spinning aluminum disc for the load. I mounted an
electromagnet that is free to rotate about the disc's axis. As the
magnetic field strength is increased, the spinning disc tries to force the
magnet to rotate. Its rotation is restricted by a pressure sensor.
I use a couple of multimeters to record the pressure and RPM then let
Excel do all the HP computational work.

It seems real easy, now that I have finished it. Fitch got me started and
showed me how to use Excel. Then Don Foreman was patient enough to guide me
thru the refinement of this dyno till he finally got me to do it right.

If your friend wants to know about dyno design, get in contact with Don
Foreman. If your friend wants pictures, I can show him what I have here.

Jerry

"Jon Anderson" wrote in message
...
I have a customer that among other things, rewinds obsolete air coil
electric motors. He has asked me about building a dyno so he can test
motors to something other than 'yep, it turns' under power.

Looking through SIC I only find one article on building a dyno. It looks
to be a fair bit of work. As he called me while on the road today and
the connection was bad, we couldn't really get into details. I am unsure
what HP and torque the motors develop, though it's not a lot. I also
don't know what rpm range he wants to test.
Did a bit of Googling and didn't find a whole lot on small model engine
sized dyno building.

Anyone know about web resources for different approaches?


Thanks,

Jon Anderson

On Fri, 03 Sep 2004 18:14:07 -0700, Jon Anderson
wrote:

I have a customer that among other things, rewinds obsolete air coil
electric motors. He has asked me about building a dyno so he can test
motors to something other than 'yep, it turns' under power.

But you don't necessarily need to know what the precise horsepower
output is? Provided that it is 'as good as the other ones we fixed'?

I don't know about the kind of motor you are working with, but many
electric motors when turned work as generators. Could you make up a
load bank of band iron strips and test the rewound motors by coupling
them to a generator (motor) whose output can be measured as this many
watts therefor that much horsepower?

Can't help much without knowing some parameters like:

range of speeds
range of power in watts or HP
required (or hoped-for) accuracy
available skills (machining, welding, building electronics, etc)
budget -- time and $

Speed and power range would narrow down the choices of the several
ways one could make a dyno. Hoped-for accuracy, available skills and
budget could save a lot of time if expectations for given resources
are clearly not consistent.

Another poster suggests a DCPM motor and load resistor. If just a
"go-nogo" test is sought, that would be a good solution with the
addition of an inexpensive voltmeter.



On Fri, 03 Sep 2004 18:14:07 -0700, Jon Anderson
wrote:

I have a customer that among other things, rewinds obsolete air coil
electric motors. He has asked me about building a dyno so he can test
motors to something other than 'yep, it turns' under power.

Looking through SIC I only find one article on building a dyno. It looks
to be a fair bit of work. As he called me while on the road today and
the connection was bad, we couldn't really get into details. I am unsure
what HP and torque the motors develop, though it's not a lot. I also
don't know what rpm range he wants to test.
Did a bit of Googling and didn't find a whole lot on small model engine
sized dyno building.

Anyone know about web resources for different approaches?


Thanks,

Jon Anderson

John,

Cell phone connection was very bad, so we couldn't discuss details. He'd
first mentioned it last week and I'd gotten as far as some Google work
and finding the SIC article. He called today as he just found out he has
a couple warranty motors coming back. It's rare for him to get a
warranty return and bugs him a great deal, he wants to get to the root
of the problem. Currently has no means to quantify performance.
They are, his description, air coil, or ironless rotor motors. Fast
response, low inertia, low HP. While he has known good motors (not
rebuilt), I don't know if he also has any specs.
I'll know more when my customer gets back next week. Did tell him I
needed to know what he was trying to measure. Going to complicate things
if he needs to measure say, rate of acceleration, etc...

At the bottom of the learning curve,

Jon

Jerry,

I'd love to see a pic, I'm the one that's going to be building whatever
he ends up using, and I'll be showing him the pic when he comes by next
week.

Will be contacting Don directly, thanks for the referral!

Jon

Don,

Ahh, my email and your post crossed on the wires!
Will have some specs when he gets back, until then I'm just trying to do
some basic research.
As far as skills, I can machine and weld up most anything needed, but
electronics theory is a real weak point. I can build simple circuits
from schematics but if something doesn't work, I'll probably never
figure out why by myself.

Thanks,

Jon

i have a homebrew rolling road dyno.
There are a couple out there for RC boat motors, etc.
Mine is at http://pages.quicksilver.net.nz/geoffm/ with some how-to-do
it info.
Geoff

On Fri, 03 Sep 2004 18:14:07 -0700, Jon Anderson wrote:
I have a customer that among other things, rewinds obsolete air coil
electric motors. He has asked me about building a dyno so he can test
motors to something other than 'yep, it turns' under power.

Looking through SIC I only find one article on building a dyno. It looks
to be a fair bit of work. As he called me while on the road today and
the connection was bad, we couldn't really get into details. I am unsure
what HP and torque the motors develop, though it's not a lot. I also
don't know what rpm range he wants to test.
Did a bit of Googling and didn't find a whole lot on small model engine
sized dyno building.

Anyone know about web resources for different approaches?

I don't have a URL for you, but I can give a verbal description of a
simple brake dyno. It is simply a brake disc which can be directly
coupled to the motor output shaft. A brake caliper is mounted on
a lever which pivots from the shaft and is restrained at the far end
by a spring scale. If the lever is 1 foot, the scale can be read directly
in foot pounds. If longer or shorter, you have to do a bit of simple
math to convert the reading to foot pounds.

To use, simply apply hydraulic pressure to the caliper until the
motor slows to the desired RPM. Read the spring scale. That's
the motor torque at that RPM. RPM times torque equals power.

By braking to a number of different RPMs and taking readings,
you can construct a graph of torque and power versus RPM
just like the big guys with the expensive engine dynos do. If
you add a current shunt to monitor motor current, you can
also plot motor current at various loads.

For motors up to several hp, you can cobble this together from
junk car parts (rotor, caliper, master cylinder) and a household
scale. Note, when braking heavily, the brake will get hot. Don't
fool around, take your reading then let off on brake pressure
and let it spin to cool.

For fractional hp motors, a motorcycle brake, or even a bicycle
caliper brake, can be used instead of an auto brake. A smaller
spring scale can be used too.

Gary

OK, no problem. We can sort out the elex, may not even need any.
Jerry uses a couple of Extech multimeters that interface to his PC.
Instrumentation is an Omega LCL series loadcell (0 to 20 lb), and
speed sensing is done by sensing teeth in a gearlike disc and logging
the frequency with an Extech. Excel does the math.

A dyno consists three key elements: something that produces drag,
something that senses torque and something that senses speed.
Torque could be sense with something as simple as a spring scale,
relative speed by the voltage output of a little DCPM motor. How the
drag part get done depends a lot on speed and power. For fractional
HP if speed is high enough, the simplest way is probably a larger
DCPM motor with a resistive load.


On Fri, 03 Sep 2004 21:21:22 -0700, Jon Anderson
wrote:

Don,

Ahh, my email and your post crossed on the wires!
Will have some specs when he gets back, until then I'm just trying to do
some basic research.
As far as skills, I can machine and weld up most anything needed, but
electronics theory is a real weak point. I can build simple circuits
from schematics but if something doesn't work, I'll probably never
figure out why by myself.

Thanks,

Jon

Disc brakes have their problems for a motor testing dyno, particularly
in testing induction motors. Speed must be maintained very closely
because the torque-speed is so steep -- 0 to rated horsepower in a
range of about 75 RPM or about 4%. The slightest bit of chatter can
really screw things up, even with a newly turned disc and new pads.
We solved that problem on Jerry's dyno by going to eddy current
braking in an aluminum disc. That was very easy to control and it was
more stable than a disc brake because it's more "viscous": drag
increases with increasing speed. A DCPM motor with external
resistive load would have that characteristic as well.

Even an ordinary induction motor with DC on its windings can work
well as a brake, , though it'll get hot if run very long.

On Sat, 04 Sep 2004 16:09:28 -0400, Gary Coffman
wrote:

On Fri, 03 Sep 2004 18:14:07 -0700, Jon Anderson wrote:
I have a customer that among other things, rewinds obsolete air coil
electric motors. He has asked me about building a dyno so he can test
motors to something other than 'yep, it turns' under power.

Looking through SIC I only find one article on building a dyno. It looks
to be a fair bit of work. As he called me while on the road today and
the connection was bad, we couldn't really get into details. I am unsure
what HP and torque the motors develop, though it's not a lot. I also
don't know what rpm range he wants to test.
Did a bit of Googling and didn't find a whole lot on small model engine
sized dyno building.

Anyone know about web resources for different approaches?

I don't have a URL for you, but I can give a verbal description of a
simple brake dyno. It is simply a brake disc which can be directly
coupled to the motor output shaft. A brake caliper is mounted on
a lever which pivots from the shaft and is restrained at the far end
by a spring scale. If the lever is 1 foot, the scale can be read directly
in foot pounds. If longer or shorter, you have to do a bit of simple
math to convert the reading to foot pounds.

To use, simply apply hydraulic pressure to the caliper until the
motor slows to the desired RPM. Read the spring scale. That's
the motor torque at that RPM. RPM times torque equals power.

By braking to a number of different RPMs and taking readings,
you can construct a graph of torque and power versus RPM
just like the big guys with the expensive engine dynos do. If
you add a current shunt to monitor motor current, you can
also plot motor current at various loads.

For motors up to several hp, you can cobble this together from
junk car parts (rotor, caliper, master cylinder) and a household
scale. Note, when braking heavily, the brake will get hot. Don't
fool around, take your reading then let off on brake pressure
and let it spin to cool.

For fractional hp motors, a motorcycle brake, or even a bicycle
caliper brake, can be used instead of an auto brake. A smaller
spring scale can be used too.

Gary

In article ,
Jon Anderson wrote:

I have a customer that among other things, rewinds obsolete air coil
electric motors. He has asked me about building a dyno so he can test
motors to something other than 'yep, it turns' under power.

Looking through SIC I only find one article on building a dyno. It looks
to be a fair bit of work. As he called me while on the road today and
the connection was bad, we couldn't really get into details. I am unsure
what HP and torque the motors develop, though it's not a lot. I also
don't know what rpm range he wants to test.
Did a bit of Googling and didn't find a whole lot on small model engine
sized dyno building.

Anyone know about web resources for different approaches?


Thanks,

Jon Anderson

I had a teacher who built a dyno with a hydraulic pump & a flow
meter. He'd use a valve to build up back pressure and monitor the flow.
After allowing for pump efficiency he could calculate the horsepower
running through the system. Knowing pump displacement he could
calculate RPM.
Simple and scalable to just about any size you need.

--
B.B. --I am not a goat! thegoat4 at airmail.net

In article ,
Jon Anderson wrote:
John,

[ ... ]

Currently has no means to quantify performance.
They are, his description, air coil, or ironless rotor motors. Fast
response, low inertia, low HP.

These sound like the servo motors used in CNC machine tools.
The low rotating mass leaves you with only the mass of the table and
workpiece (or whatever else is being moved) to tune.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"B.B." u wrote in message
news
In article ,
Jon Anderson wrote:

I have a customer that among other things, rewinds obsolete air coil
electric motors. He has asked me about building a dyno so he can test
motors to something other than 'yep, it turns' under power.

Looking through SIC I only find one article on building a dyno. It looks
to be a fair bit of work. As he called me while on the road today and
the connection was bad, we couldn't really get into details. I am unsure
what HP and torque the motors develop, though it's not a lot. I also
don't know what rpm range he wants to test.
Did a bit of Googling and didn't find a whole lot on small model engine
sized dyno building.

Anyone know about web resources for different approaches?


Thanks,

Jon Anderson

I had a teacher who built a dyno with a hydraulic pump & a flow
meter. He'd use a valve to build up back pressure and monitor the flow.
After allowing for pump efficiency he could calculate the horsepower
running through the system. Knowing pump displacement he could
calculate RPM.
Simple and scalable to just about any size you need.

--
B.B. --I am not a goat! thegoat4 at airmail.net

BB

I've got a little pump-dyno here where I mounted the pump so it is free to
rotate. Then, when the flow is restricted, the pump tries to rotate.
When I measure the torque imposed on the pump and the shaft RPM, I assume I
can calculate HP with Excel. But, the idea of several GPM at a thousnd +
PSI scares me enough that I dont want to test it in the garage. I might
get courage to test it on a fractional HP motor. All the other dyno loads
I've tried get too hot when loaded for even a few minutes. Water spray
helps extend the test run time, but even the water makes a little mess.

Jerry

In article gIw_c.2426$j62.422@trnddc04,
"Jerry Martes" wrote:

[...]

Anyone know about web resources for different approaches?


Thanks,

Jon Anderson

I had a teacher who built a dyno with a hydraulic pump & a flow
meter. He'd use a valve to build up back pressure and monitor the flow.
After allowing for pump efficiency he could calculate the horsepower
running through the system. Knowing pump displacement he could
calculate RPM.
Simple and scalable to just about any size you need.

--
B.B. --I am not a goat! thegoat4 at airmail.net

BB

I've got a little pump-dyno here where I mounted the pump so it is free to
rotate. Then, when the flow is restricted, the pump tries to rotate.
When I measure the torque imposed on the pump and the shaft RPM, I assume I
can calculate HP with Excel. But, the idea of several GPM at a thousnd +
PSI scares me enough that I dont want to test it in the garage. I might
get courage to test it on a fractional HP motor. All the other dyno loads
I've tried get too hot when loaded for even a few minutes. Water spray
helps extend the test run time, but even the water makes a little mess.

Jerry

I believe that if you measure only the torque load of the pump trying
to twist loose you'll only be able to calculate pressure--you would
still need to know flow rate coming out of the pump. I suppose if you
know the pump RPM and the pump's efficiency you could calculate the
flow. But you'd need to recalibrate your setup occasionally as the pump
wears.
If you're worried about the hydraulics blowing up you only need to
have pressure-rated hardware from the pump through the flow meter, to
the restricter valve. Outside of that area everything will stay
low-pressure. Many pumps come with a built-in relief valve so you can
set that to keep the system from exploding if you crank the valve down
all the way. And many flow meters come with a built-in restriction
valve, so you won't need to worry about that either.
The two dangers with a hydraulic system are pinhole leaks and a burst
throwing hardware. Use pressure-rated hardware and keep a relief valve
set slightly below the working pressures and you'll be fine. If you use
a large enough pump you could even do all of your dynoing at only a few
hundred PSI--but that gets somewhat expensive and less accurate.
I didn't study my teacher's dyno too closely, but from what I could
see he apparently used an old drum as a reservoir to allow the oil to
cool. It was actually quite a clean setup--I only saw oil residue
around the vent on the barrel.
FWIW he used his to test transmissions he built and had a chevy V8
driving them. His dyno never had a problem with high horsepower.

--
B.B. --I am not a goat! thegoat4 at airmail.net

Don,

Can't say exactly what the motors are used for, but it's not CNC. I can
say though, the overall technology is 30+ years old and the original
manufacturer is on record saying nobody could successfully rebuild them.
My customer enjoyed the challenge!

Jon

"B.B." u wrote in message
news
In article gIw_c.2426$j62.422@trnddc04,
"Jerry Martes" wrote:

[...]

Anyone know about web resources for different approaches?


Thanks,

Jon Anderson

I had a teacher who built a dyno with a hydraulic pump & a flow
meter. He'd use a valve to build up back pressure and monitor the
flow.
After allowing for pump efficiency he could calculate the horsepower
running through the system. Knowing pump displacement he could
calculate RPM.
Simple and scalable to just about any size you need.

--
B.B. --I am not a goat! thegoat4 at airmail.net

BB

I've got a little pump-dyno here where I mounted the pump so it is free
to
rotate. Then, when the flow is restricted, the pump tries to rotate.
When I measure the torque imposed on the pump and the shaft RPM, I assume
I
can calculate HP with Excel. But, the idea of several GPM at a thousnd +
PSI scares me enough that I dont want to test it in the garage. I might
get courage to test it on a fractional HP motor. All the other dyno
loads
I've tried get too hot when loaded for even a few minutes. Water spray
helps extend the test run time, but even the water makes a little mess.

Jerry

I believe that if you measure only the torque load of the pump trying
to twist loose you'll only be able to calculate pressure--you would
still need to know flow rate coming out of the pump. I suppose if you
know the pump RPM and the pump's efficiency you could calculate the
flow. But you'd need to recalibrate your setup occasionally as the pump
wears.
If you're worried about the hydraulics blowing up you only need to
have pressure-rated hardware from the pump through the flow meter, to
the restricter valve. Outside of that area everything will stay
low-pressure. Many pumps come with a built-in relief valve so you can
set that to keep the system from exploding if you crank the valve down
all the way. And many flow meters come with a built-in restriction
valve, so you won't need to worry about that either.
The two dangers with a hydraulic system are pinhole leaks and a burst
throwing hardware. Use pressure-rated hardware and keep a relief valve
set slightly below the working pressures and you'll be fine. If you use
a large enough pump you could even do all of your dynoing at only a few
hundred PSI--but that gets somewhat expensive and less accurate.
I didn't study my teacher's dyno too closely, but from what I could
see he apparently used an old drum as a reservoir to allow the oil to
cool. It was actually quite a clean setup--I only saw oil residue
around the vent on the barrel.
FWIW he used his to test transmissions he built and had a chevy V8
driving them. His dyno never had a problem with high horsepower.

--
B.B.

BB

I dont know how to measure flow. I could probably learn But, I think
here is no need to measure flow in the hydraulic path in order to measure
motor HP. The pump is doing the work on the fluid. The motor supplies the
power to the pump. I wanted to know only how muvh work the motor is doing.
It is pretty essy to measure and record motor RPM. I figure the pump could
be mounted firmly and measure the motor's torque with the motor base free to
spin - or - Mount the motor firmly and allow the pump to rotate.
I'm pretty confidant the motor's HP can be calculated by measurement of
the pump's shaft RPM and the pump Torque.

Although I did get a pump and valve that are rated for the pressure I'd
generate, I got woried about the 1,500 PSI finding some way of making me
realize I had made some mistake. 1,500 PSI and 5 GPM of hydraulic oil could
make my garage look terrible. I'll test it outside whenever I do need to
load a motor for more than 5 or 10 minutes.

Jerry

On Sun, 05 Sep 2004 17:39:45 GMT, "Jerry Martes" wrote:
I dont know how to measure flow. I could probably learn But, I think
here is no need to measure flow in the hydraulic path in order to measure
motor HP. The pump is doing the work on the fluid. The motor supplies the
power to the pump. I wanted to know only how muvh work the motor is doing.
It is pretty essy to measure and record motor RPM. I figure the pump could
be mounted firmly and measure the motor's torque with the motor base free to
spin - or - Mount the motor firmly and allow the pump to rotate.
I'm pretty confidant the motor's HP can be calculated by measurement of
the pump's shaft RPM and the pump Torque.

Yes. You are simply using the pump as an adjustable brake. You don't
need to know, or care, what the pump's efficiency is. You don't need to
know or care what pressure or flow it produces. All you need to know
to calculate motor hp is RPM and torque. A load cell, or even a lever
arm and spring scale, restraining the pump from rotating will give you
torque. You can measure RPM directly. hp = RPM x torque.

Gary

In article gIw_c.2426$j62.422@trnddc04,
says...



I've got a little pump-dyno here where I mounted the pump so it is free to
rotate. Then, when the flow is restricted, the pump tries to rotate.
When I measure the torque imposed on the pump and the shaft RPM, I assume I
can calculate HP with Excel. But, the idea of several GPM at a thousnd +
PSI scares me enough that I dont want to test it in the garage. I might
get courage to test it on a fractional HP motor. All the other dyno loads
I've tried get too hot when loaded for even a few minutes. Water spray
helps extend the test run time, but even the water makes a little mess.

Jerry

If the hydraulics are done properly I wouldn't be too
concerned. I've got the schematics here for a 100 HP test
stand I designed and built for one of the big hydraulics
mfrs. for testing high speed hydraulic pumps and motors. As
well as testing both pumps and motors, it checked
volumetric efficiency and went thru an automated sequence
while logging data, so I'm sure it's much more elaborate
than what you've got, but if you're interested in the
schematics let me know.

Ned Simmons

In article , dnichols@d-
and-d.com says...
In article ,
Jon Anderson wrote:
John,

[ ... ]

Currently has no means to quantify performance.
They are, his description, air coil, or ironless rotor motors. Fast
response, low inertia, low HP.

These sound like the servo motors used in CNC machine tools.
The low rotating mass leaves you with only the mass of the table and
workpiece (or whatever else is being moved) to tune.


Unless the load is very large, or the stroke very short,
the largest inertia the motor in a screw driven postioning
system sees is usually the screw itself.

Ned Simmons

"Ned Simmons" wrote in message
...
In article gIw_c.2426$j62.422@trnddc04,
says...



I've got a little pump-dyno here where I mounted the pump so it is
free to
rotate. Then, when the flow is restricted, the pump tries to rotate.
When I measure the torque imposed on the pump and the shaft RPM, I
assume I
can calculate HP with Excel. But, the idea of several GPM at a thousnd
+
PSI scares me enough that I dont want to test it in the garage. I
might
get courage to test it on a fractional HP motor. All the other dyno
loads
I've tried get too hot when loaded for even a few minutes. Water spray
helps extend the test run time, but even the water makes a little mess.

Jerry

If the hydraulics are done properly I wouldn't be too
concerned. I've got the schematics here for a 100 HP test
stand I designed and built for one of the big hydraulics
mfrs. for testing high speed hydraulic pumps and motors. As
well as testing both pumps and motors, it checked
volumetric efficiency and went thru an automated sequence
while logging data, so I'm sure it's much more elaborate
than what you've got, but if you're interested in the
schematics let me know.

Ned Simmons

Ned

My problems are associated with a poor decission I made in the design of
this little dyno. I wanted the drag on the load's rotation to be minimal.
So, I made the lines into and out of the pump as flexible as possible. I
thought the output hose could be "light weight" because it is such low
pressiure. My brother-in-law spent his life designing hydraulics for
Northrop. He told me storries about high pressure liquids punching small
holes in outlet hoses due to some caracteristic of high pressure pumps. I
thought -- Oh Sh*t. Since I have other things to occupy my time, I dropped
that dyno for a while.

I appreciate your offer to share your dyno information with me. I wish I
could get involved with a project that uses a big dyno.

What kind of instruments do you use to log the data. I got a Lab Jack but
get confused about how to use it.

Jerry.

"Jerry Martes" wrote in message
news:5lS_c.4605$vI2.1373@trnddc02...

"Ned Simmons" wrote in message
...
In article gIw_c.2426$j62.422@trnddc04,
says...



I've got a little pump-dyno here where I mounted the pump so it is
free to
rotate. Then, when the flow is restricted, the pump tries to rotate.
When I measure the torque imposed on the pump and the shaft RPM, I
assume I
can calculate HP with Excel. But, the idea of several GPM at a
thousnd
+
PSI scares me enough that I dont want to test it in the garage. I
might
get courage to test it on a fractional HP motor. All the other dyno
loads
I've tried get too hot when loaded for even a few minutes. Water
spray
helps extend the test run time, but even the water makes a little
mess.

Jerry

If the hydraulics are done properly I wouldn't be too
concerned. I've got the schematics here for a 100 HP test
stand I designed and built for one of the big hydraulics
mfrs. for testing high speed hydraulic pumps and motors. As
well as testing both pumps and motors, it checked
volumetric efficiency and went thru an automated sequence
while logging data, so I'm sure it's much more elaborate
than what you've got, but if you're interested in the
schematics let me know.

Ned Simmons

Ned

My problems are associated with a poor decission I made in the design of
this little dyno. I wanted the drag on the load's rotation to be minimal.
So, I made the lines into and out of the pump as flexible as possible. I
thought the output hose could be "light weight" because it is such low
pressiure. My brother-in-law spent his life designing hydraulics for
Northrop. He told me storries about high pressure liquids punching small
holes in outlet hoses due to some caracteristic of high pressure pumps. I
thought -- Oh Sh*t. Since I have other things to occupy my time, I
dropped
that dyno for a while.

I appreciate your offer to share your dyno information with me. I wish
I
could get involved with a project that uses a big dyno.

What kind of instruments do you use to log the data. I got a Lab Jack
but
get confused about how to use it.

Jerry.


The go kart guys have all sorts of unique "dynos". Your eddy current one
sounds pretty cute though.

In article ,
Jon Anderson wrote:
Don,

Can't say exactly what the motors are used for, but it's not CNC. I can
say though, the overall technology is 30+ years old and the original
manufacturer is on record saying nobody could successfully rebuild them.
My customer enjoyed the challenge!

I *like* that. :-)

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"Rick" wrote in message
ink.net...

"Jerry Martes" wrote in message
news:5lS_c.4605$vI2.1373@trnddc02...

"Ned Simmons" wrote in message
...
In article gIw_c.2426$j62.422@trnddc04,
says...



I've got a little pump-dyno here where I mounted the pump so it is
free to
rotate. Then, when the flow is restricted, the pump tries to
rotate.
When I measure the torque imposed on the pump and the shaft RPM, I
assume I
can calculate HP with Excel. But, the idea of several GPM at a
thousnd
+
PSI scares me enough that I dont want to test it in the garage. I
might
get courage to test it on a fractional HP motor. All the other
dyno
loads
I've tried get too hot when loaded for even a few minutes. Water
spray
helps extend the test run time, but even the water makes a little
mess.

Jerry

If the hydraulics are done properly I wouldn't be too
concerned. I've got the schematics here for a 100 HP test
stand I designed and built for one of the big hydraulics
mfrs. for testing high speed hydraulic pumps and motors. As
well as testing both pumps and motors, it checked
volumetric efficiency and went thru an automated sequence
while logging data, so I'm sure it's much more elaborate
than what you've got, but if you're interested in the
schematics let me know.

Ned Simmons

Ned

My problems are associated with a poor decission I made in the design
of
this little dyno. I wanted the drag on the load's rotation to be
minimal.
So, I made the lines into and out of the pump as flexible as possible.
I
thought the output hose could be "light weight" because it is such low
pressiure. My brother-in-law spent his life designing hydraulics for
Northrop. He told me storries about high pressure liquids punching
small
holes in outlet hoses due to some caracteristic of high pressure pumps.
I
thought -- Oh Sh*t. Since I have other things to occupy my time, I
dropped
that dyno for a while.

I appreciate your offer to share your dyno information with me. I
wish
I
could get involved with a project that uses a big dyno.

What kind of instruments do you use to log the data. I got a Lab Jack
but
get confused about how to use it.

Jerry.


The go kart guys have all sorts of unique "dynos". Your eddy current one
sounds pretty cute though.

Rick

I didnt do much research on dynos before I began building mine. I did try
to understand the "Inertia Dyno" that is used for Kart engine testing. I
would think the inertia Dyno would be hard to beat for Kart engines.
I suspect there much better versions of the eddy current dyno that the one
I built. The only good thing I have to say about this spinning aluminum
disc it "it is easy to build and operate at home". Don Foreman actually
suggestedthis concept to me (spinning aluminum disc). It was too simple to
ignore. It is really easy to control so the data is quite repeatable. The
disc brake loads I *was* building are very difficult to make smooth. They
tend to skew the data due to pulsating effects from any small imperfections
in the disc and/or caliper.
I doubt that anything I know about eddy current dynos would be interesting
to anyone in the Kart business. I just sold my Kart this week.

Jerry

"Jerry Martes" wrote in message
news:M1T_c.2196$Va5.1860@trnddc01...
The go kart guys have all sorts of unique "dynos". Your eddy current one
sounds pretty cute though.

Rick

I didnt do much research on dynos before I began building mine. I did
try
to understand the "Inertia Dyno" that is used for Kart engine testing. I
would think the inertia Dyno would be hard to beat for Kart engines.
I suspect there much better versions of the eddy current dyno that the
one
I built. The only good thing I have to say about this spinning aluminum
disc it "it is easy to build and operate at home". Don Foreman actually
suggestedthis concept to me (spinning aluminum disc). It was too simple
to
ignore. It is really easy to control so the data is quite repeatable.
The
disc brake loads I *was* building are very difficult to make smooth. They
tend to skew the data due to pulsating effects from any small
imperfections
in the disc and/or caliper.
I doubt that anything I know about eddy current dynos would be
interesting
to anyone in the Kart business. I just sold my Kart this week.

Jerry


These guys have some neat little ones, too:

http://www.land-and-sea.com/kart-dyn...rrent-dyno.htm

All depends on what they are looking for. Inductors are reliable and used
extensively. Can't beat them for simplicity, but you can't beat a good DC
machine for versatility...

In article 5lS_c.4605$vI2.1373@trnddc02,
"Jerry Martes" wrote:

[...]

My problems are associated with a poor decission I made in the design of
this little dyno. I wanted the drag on the load's rotation to be minimal.
So, I made the lines into and out of the pump as flexible as possible. I
thought the output hose could be "light weight" because it is such low
pressiure. My brother-in-law spent his life designing hydraulics for
Northrop. He told me storries about high pressure liquids punching small
holes in outlet hoses due to some caracteristic of high pressure pumps. I
thought -- Oh Sh*t. Since I have other things to occupy my time, I dropped
that dyno for a while.

Unless you wind it up really tight or kink it a hose rated for 6,000
PSI working pressure would have to be spiked up well over 6,000 PSI many
times before developing a pinhole. Even then it's not very likely.
Also, the pinhole leaks are easily contained with a plastic hose wrap.
It's just a plastic spiral that you can wrap around the hose to protect
it. It's heavy enough a pinhole leak isn't going to cut through it at
any realistic operating pressures. You'd just see a dribble of oil
coming out of it near the leak.
Are you trying to actually spin the pump around or do you just want
to let it rotate a few degrees to push on a strain gauge or some such?
If it's spinning around, then yeah, that's dangerous and crazy and I'd
stay away from it. But if only rotating a few degrees you can use stiff
hoses without hurting your measurements. You could also just use a
pressure gauge on the pump and correlate input torque to pump pressure.

--
B.B. --I am not a goat! thegoat4 at airmail.net

On Fri, 03 Sep 2004 18:14:07 -0700, Jon Anderson
vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

I must warn you that the making of explosi....oh..Sorry
************************************************** ***
I know I am wrong about just about everything. So I
am not going to listen when I am told I am wrong about
the things I know I am right about.

"B.B." u wrote in message
news
In article 5lS_c.4605$vI2.1373@trnddc02,
"Jerry Martes" wrote:

[...]

My problems are associated with a poor decission I made in the design
of
this little dyno. I wanted the drag on the load's rotation to be
minimal.
So, I made the lines into and out of the pump as flexible as possible. I
thought the output hose could be "light weight" because it is such low
pressiure. My brother-in-law spent his life designing hydraulics for
Northrop. He told me storries about high pressure liquids punching small
holes in outlet hoses due to some caracteristic of high pressure pumps.
I
thought -- Oh Sh*t. Since I have other things to occupy my time, I
dropped
that dyno for a while.

Unless you wind it up really tight or kink it a hose rated for 6,000
PSI working pressure would have to be spiked up well over 6,000 PSI many
times before developing a pinhole. Even then it's not very likely.
Also, the pinhole leaks are easily contained with a plastic hose wrap.
It's just a plastic spiral that you can wrap around the hose to protect
it. It's heavy enough a pinhole leak isn't going to cut through it at
any realistic operating pressures. You'd just see a dribble of oil
coming out of it near the leak.
Are you trying to actually spin the pump around or do you just want
to let it rotate a few degrees to push on a strain gauge or some such?
If it's spinning around, then yeah, that's dangerous and crazy and I'd
stay away from it. But if only rotating a few degrees you can use stiff
hoses without hurting your measurements. You could also just use a
pressure gauge on the pump and correlate input torque to pump pressure.

--
B.B. --

BB

The motor is mounted firmly and the pump is mounted inside a big ball
bearing from a VW Bug transaxel. So, the pump's shaft is connected to the
motor's shaft and the pump body is free to rotate. The pump body is
restricted from rotating by a ~ 1 foot long bar.

I think you could have been a big help to me when I made this. My plan
was to keep the 'resistance to pump rotation' at a minimum so the residual
drag would be low and low HP could be recorded. So, I used some very low
pressure hose on the outlet.
I thought the spiking might be eliminated as a problem if the pump outlet
had a metal U at its outlet. I put the U at the pump outlet and stopped
working on the load since I got interested in the eddy current load at the
same time I was finishing the hydraulic pump load.
I'd bet that you could solve another problem I wonder about with this pump
load. I bagan to worry about how to get the oil to swiril properly in the
~ 5 gallon oil reservoir.

Note, all the dyno loads I've tried so far cant be used for more than a
few minutes at 5 HP without coolant spray. So, the hydraulic load would be
a good device for any "motor heat' testing. Thats why I havent disassembled
it yet.

Please let me know if you are available for information on how critical
the reservoir size and shape will be.

Thanks
Jerry

In article rJ0%c.3061$Va5.224@trnddc01,
"Jerry Martes" wrote:

[...]

BB

The motor is mounted firmly and the pump is mounted inside a big ball
bearing from a VW Bug transaxel. So, the pump's shaft is connected to the
motor's shaft and the pump body is free to rotate. The pump body is
restricted from rotating by a ~ 1 foot long bar.

Neat setup.

I think you could have been a big help to me when I made this. My plan
was to keep the 'resistance to pump rotation' at a minimum so the residual
drag would be low and low HP could be recorded. So, I used some very low
pressure hose on the outlet.

How low? The working pressure should be printed on the hose. If
it's not, then yes, you should fear that hose. However, if it is rated
then as long as you stay under the printed working pressure you'll be
just fine even if it is a really flexible hose.
Since your pump is rotating only very slightly you can use a fairly
stiff hose without interfering with your measurements.

I thought the spiking might be eliminated as a problem if the pump outlet
had a metal U at its outlet. I put the U at the pump outlet and stopped
working on the load since I got interested in the eddy current load at the
same time I was finishing the hydraulic pump load.

Hmm, I don't see how a U will eliminate spiking. Do you mean big
pressure spikes or just pulsation? The pulsation might be a result of
the pump you use--gear pumps pulse a lot. You can dampen that with an
accumulator. Or just use a liquid dampened gauge if you want to check
pressures as the gauge itself will more or less average the pulses
together. But if you're using the foot-long arm and a strain gauge
setup you won't really need to monitor pressure too closely.
If the pulsing is bad enough to cause speed fluctuations in the
motors you're testing you'll have to go to a smaller pump with higher
pressures or a different style of pump for more money. Or you could
stick a big flywheel somewhere to smooth things out.
If you're getting actual spikes you're doing something weird as this
setup should allow you to slowly build pressure.

I'd bet that you could solve another problem I wonder about with this pump
load. I bagan to worry about how to get the oil to swiril properly in the
~ 5 gallon oil reservoir.

The suction line to the pump should connect near the bottom of the
reservoir, and the return line should connect near the top. You don't
need swirl, really, you just need the oil to spend a reasonable amount
of time in there so it can cool. A simple single baffle within the tank
between the inlet and outlet is plenty. But often you can get by
without even that by placing the in & out connections far enough apart.
Remember to include a filter somewhere.

Note, all the dyno loads I've tried so far cant be used for more than a
few minutes at 5 HP without coolant spray. So, the hydraulic load would be
a good device for any "motor heat' testing. Thats why I havent disassembled
it yet.

Please let me know if you are available for information on how critical
the reservoir size and shape will be.

http://www.surpluscenter.com/Hydraulic.htm
I'm no engineer, I just know what I've seen. That page covers the
basics. The only thing I'd add is to paint the outside of the tank
black.

--
B.B. --I am not a goat! thegoat4 at airmail.net

In article 5lS_c.4605$vI2.1373@trnddc02,
says...


Ned

My problems are associated with a poor decission I made in the design of
this little dyno. I wanted the drag on the load's rotation to be minimal.
So, I made the lines into and out of the pump as flexible as possible. I
thought the output hose could be "light weight" because it is such low
pressiure. My brother-in-law spent his life designing hydraulics for
Northrop. He told me storries about high pressure liquids punching small
holes in outlet hoses due to some caracteristic of high pressure pumps. I
thought -- Oh Sh*t. Since I have other things to occupy my time, I dropped
that dyno for a while.

I appreciate your offer to share your dyno information with me. I wish I
could get involved with a project that uses a big dyno.

What kind of instruments do you use to log the data. I got a Lab Jack but
get confused about how to use it.


The date on the print is 1987 and I didn't do the data
logging portion of the job, so my memory is fuzzy, but I
believe it was a data acquisition card in a PC running a
Labview type application. Torque was measured with a
Himmelstein torque transducer

http://www.himmelstein.com/

and flows were measured by monitoring encoders on the
shafts of motors that were specially selected for low
leakage.

Other than all the complications that resulted from having
to perform bi-directional tests on both pumps and motors,
and run a pre-determined sequence, the basic operation of
these stands was probably not much different than what
you're trying.

Ned Simmons

Ned Simmons

Rick wrote:

These guys have some neat little ones, too:

http://www.land-and-sea.com/kart-dyn...rrent-dyno.htm

I didn't rush to check this site out since kart engines are way beyond
what we'll be trying to measure, but after finally taking a look, I'm
impressed. Especially the tiny dyno stand with the model airplane
engine. Have requested a catalog.
Thanks for the link!

Jon