MW Dyno -- anyone have tips on operating one

We just bought a M&W model P-4450 dyno. I've never used one in my life. I'm going to pick this thing up next week. Does anyone have any tips on operating one?

Lift cover on oil, it should be clean with no milky tint and full to mark. The water cooling radiator element can develop age related corrosion pinhole leaks that are hard to repair and results in milky oil that will freeze in low temps and cause added damage.
Check all of the hoses under the control valve.
Make sure you get the operators manual. They were
still available from M&W 3 years ago. Have seller
hook it up, operate it, then you do it. You can't
pull much over 50HP for more than 5 minutes without running auxillary water cooling. If you use it to break in an overhaul, you have to be able to use auxillary water cooling.

Although it has been close to 3o years since I ran one but they are dirt simple to operate. Like Mel said a manual is always good, I would add that the gauges are notorious for going out of calibration and EXPENSIVE to repair. There is an operator adjusted gauge snubber right where you can see it,, USE it! it realy saves the gauge.

Anytime one is running there are guys around saying, "Ya the operator can make them say whatever he wants them to say" That is pure horse hockey, but you will find that out on your own, have fun with it.

His question still hasn't been answered......how do operate the damned thing! I'd like to know the answer, myself.

I have watched them being used and asked questions of the operator(s) and all I ever got were mumbles.....which lead me to believe they really didn't know the answers.

By your question appearantly you think there is magic involved or you dont understand what HP is so here goes again only the long winded way.

The M&W dyno has two gauges
One gauge reads directly in horsepower
Depending on the version of the gauge it may also read torque in foot pounds
It also has an RPM gauge

Horsepower is NOT torque
Horsepower is not RPM
Horsepower is the product of torque and RPM
divided by a standardised calculating number I didnt bother to look up. Google it if you want to know the exact formula it is not important here. What is important for you to know at this point is what horsepower is, not the exact formula.

That being said and understood the inner workings of the dyno and the calibration of the gauge combine to give the operator a direct reading of horsepower being applied by the dyno at any given time, no calculation, no slight of hand, no matter 100 RPM or ??? RPM, no matter if green, red or purple painted power on the shaft no matter if 1 cylinder tractor or 31.
A properly trained 5 year old could "run" an M&W and and Albert Einstien cannot make it read something other than HP being used and applied. I cannot over stress these things to those who think there is voodoo involved in its operation,,, or in what is powering it.

Myths and BS thrown out and HP knowledge at hand you apply a load with one by turning the handwheel to the right. The dyno applies a load and the HP needed is pull that load reads on the gauge.
Most older tractors were rated at 540 RPM so you crank it up wide open then pull the RPMS down to 540 with the dyno and stop. You then read the HP directly on the the gauge, nothing to adjust, nothing to calculate. You are pulling X HP at 540 RPM

Now if you are looking for maximum horsepower avaialable, instead of horsepower at 540 RPM, you do same except watch the gauge. The gauge will rise as you apply a load and the governor opens to accpet it. Once the governor has the carb or fuel rack wide open the next thing that happens as you apply a load is the RPM will fall. Most generaly the most HP is produced at the point where RPMs just start to fall, but not always, depends on engine design but it will always be very near that point of the RPMs dropping.

'Bout as clear and simple as I know how to make it for ya'll

You forgot to mention you have to factor in barometric pressure and temp. I have a slide rule that came with mine that you use to give you the corrected hp.

Yes the air temp and pressure affect the power produced but you are confusing the issues here. No matter the temp or pressure the gauge reads the horsepower being produced,,period.

The correction factors are simply so a person who cant sleep becuse his 4020 only produced 90.5 HP on a dyno can see tha it is becuse he tested it on a 98 degree day just before a thunder shower hit. (low B.P.)

Mark,
Maybe the list you are looking for a new operator would be: 1)Hook dyno to tractor drawbar, 2) connect pto, 3)start tractor, run for 6+ minutes to bring motor up to normal operating temp, 4) engage pto and raise pto rpm above 540, 5) turn dyno brake handwheel clockwise
until pto rpm is pulled down to, and stabilized at, 540rpm, 6) read HP directly from dial, and
7)correct to standard conditions if you want to compare readings taken on different days or in
different locations. I have only used the M&W
P400 myself and if I remember correctly the manual
gives slightly different direction for taking readings on gas and diesel tractors. I believe the list I gave above is for diesel, but the differences are clearly stated in the manual.

These detailed explanations make it much more clear as to how:

the dyno works

what the dyno measures

how the dyno converts the load applied to HP delivered

and finally,

the procedure as how the dyno is is set up to measure the HP.

This is the information I have always wanted to learn and by you taking the time to discuss it thoroughly, I have at last learned something. Thank you.

If I remember correctly, HP=torque x speed divided by 5252. Bob

This particular one has digital readouts instead of gauges and is supposed to measure up to something like 625 hp. It is supposed to have all of the manuals / paperwork with it. I was curious about general maint. and care, though. I'm planning to pick it up next week and am pretty excited to try it out.

Your right. He would now know why it only produced the 90.5 HP as you say. He doesn't have to wonder if it needs tweaking if it is off some from what it is supposed to be. They didn't make and include the slide rule just for the heck of it I am sure.

parrothead,
Your P4450 sounds like it has some nice improvements. Your M&W dyno is an oil pump hooked
to your tractor's pto. The brake handwheel is a
precision valve that allows you to restrict the output of the oil pump and read out the restriction in HP. They are a remarkably rugged, stable, and repeatable instrument if they are used
and maintained as directed in the manual. Same oil as listed, etc. I am sure you will enjoy using it for years to come.