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Re: (ET) motors
*Nod* Except for the fact that the other two motors are now spinning at
4/3rd their RPM or faster. At a certain point the bearings will be
overstressed, or even worse the blade will rip apart.
If you stall two motors for even the most innocent of reasons (say
cutting grass in a strip) motor 3 will go to 9,000 or so RPM. That will
be bad. Also I am not sure how three motors would brake down when
shorted; remember that is an important feature in the Elec-Trak, the
blade really has to stop spinning within a second or two.
I think the design of some DC-DC converters is the way to go here. I'm
going to work on a 24 volt one, I see no reason why we can't just build
a module to convert 36 volts down to 12 volts for the deck motors. Only
problem is the current requirements go up by a factor of three. Braking
could be addressed with a crowbar relay attached to a capacitor and a
low voltage detection sensor.
You are right, but that is a SAFETY FEATURE. Most cutting involves the inertia of the motor.
It is turning 3,000 RPM. If the resistance is brief, a fraction of a second, the change in
speed is small. If you hit something, you WANT IT TO STOP.