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