The simplest and cheapest solution might be a big trailer disk
brake. About $160.
http://www.trailerpartsdepot.com/itemdesc.asp?CartId={316C1101-2A63-4A70-814C-
A4721EVERESTC6CE132}&ic=81104&eq=81104A&Tp=
Make an adapter plate/flange to match the prop flange. This is the
hardest part, but not all that difficult. The bolt circle for an SAE 2
prop is 4.75" and the bolt circle for the trailer wheel is 5.5". You
could probably drill new holes through the brake rotor and trailer hub
and just use a simple spacer.
Bolt a nice long extension on the caliper arm and get your torque
information from the force needed to keep that extension arm in place.
(Use a scale, or a load cell if you want to get fancy.) Make the
extension arm long so that you don't put too much side force on the
front bearing or the engine mounts. Adjust the torque with weights on
the brake actuator arm or a porta-power pump with a gauge. The torque
will be roughly proportional to the hydraulic pressure.
Direct the garden hose into the middle of the disk so the water goes
through the vented disk. Make a sheet metal "fender" to contain the
spray. Water is cheap and you are not going to run this thing for weeks
at a time.
Bill Dube'
I like this idea Bill. When converting water to steam it absorbs
a lot of calories. In fact I mentioned spraying water on a disk brake
in a book I wrote years ago on race car braking systems.
The big advantage Doug, is you can measure HP at many different RPMs
while with a wood prop club only at one RPM.
Paul Lamar ...No rotor no motor
Thanks Bill,
This sounds like the best way to go. I've heard of brake loading dynos but
I was concerned they would soon overheat. Cool it with water. Cool!!!
Timely suggestion as well. I was just trying to figure out how to support
all those staggered boards in the hydraulic press to get a good bond. I was
going to buy them all tomorrow.
Actually I can get truck disc brake discs easily. Misubishi Corp. has been
having a lot of trouble with their bus and large truck wheels falling off in
the last year. Sales are way down. Seemed they have been covering up the
casting problem for years. I should be able to get all the parts for free:)
Yea and measure torque as well which I believe would be harder to
extrapolate from water pressure as the temperature is fluctuating rapidly.
Which side of the engine should I put the brake arm lever? Opposite side of
revolution?
Doug Fir.
Depends on how you locate the load sensor. Do you want the load
sensor beam to go up or down? You can use everything you have.
Just anchor the brake caliber to the base frame so it cannot rotate.
BTW make sure they are hydraulic and not air. Hydraulic is easier.
Lots of truck brakes are air actuated. If air you will need some type
of air compressor and a way of controlling it. Shop air may be OK.
Also get the brake pedal assemble including master cylinder and or air
control valve out of the truck cab.
The water cooling system is total loss so the temp matters not.
Here are a few 3Ds
Paul Lamar ...No rotor no motor.
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