[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: (ET) Power of Elec-trak motors?
David Roden wrote:
Not that way. As I suggested before, measuring the power into the motor
tells you nothing about the manufacturer's rating of that motor. You could
even measure the output on a dynamometer, and you STILL wouldn't know
anything more than you do now.
Ok, but what you can find out with this method is how much power you
will *need*. It's a simple fact that you need power to move the tractor
and swing the blades. Whether you do it with a super-overamped slot car
motor or a locomotive motor you still need a certain amount of power.
What I have posted is the amount of power I have noticed are needed to
do things. It takes 1,440 watts to move my Elec-trak from level ground
point a to point B. It takes about 3,600 watts for my Elec-trak to move
from level point A to point B with the mower blades chewing through grass.
Does anyone else have an E-Meter to cross-check these numbers?
Convert that into HP numbers and you come up with 1.8hp to move around
and 4hp to mow away. And that is on a very direct-drive tractor. No
pulleys on the deck, no real belts, no power-robbing idlers.
Now if I am mowing up a hill I'll pull a lot more power on the drive
motor. And heat will start to build up. Once I go back to level at the
top, the motor will start to cool down again. So heat becomes like a
bathtub filling with water. If I can get to the top before I overheat
the motor then no problems. That's why it's nice to have a big motor
that can dump excess heat when needed. And why the mower motors have
Klixon switches on the top. If they really overload for a period of time
they will shut down before melting the armatures.
But you still need 1,440 watts to drive on level ground, and 3,600 to
mow away. That doesn't change no matter what you do.
GE would have no incentive to lie about their motors, other than in their
advertising. <g> If the published engineering data say the drive motor is
rated at 1hp, most likely it is, as puzzling as that may be to folks used to
the way ICEs are rated for absolute peak horsepower.
That's the question then, what is the true rating of these motors?
They're big, but they are also sealed, which always made me wonder how
they get rid of their heat. Do golf cart motors have fans? How happy are
they going to be when they get covered in ground up leaf/grass/dirt debris?
As for cars, it takes 18kw of power to move my Prizm at 60mph on level
ground. Yes a 5kw motor could do the job, but it would probably overheat
quickly. So I need a motor that can put out 18kw constantly if I want to
drive it at 60mph.
Given that, it's not surprising that GE ads claimed (in a cringe-inducing
confusion of units) that with a 1hp motor "peak torque exceeds 14
horsepower."
And it might. I can do things with my E20 that will literally stall my
15.5hp Craftsman. Pull down trees and the like. So it's not a totally
unfair thing to say.
But you still need a certain amount of power to mow. Size your motor
accordingly.
Chris