RE: (ET) Mower motor strength requirements

["Elie, Larry \(L.D.\)" <lelie ford com>]

I adapted a deck motor to a 2" water pump normally powered by a B&S 3 hp. 
engine at 3600 RPM several 
years ago.  I measured the water lift and volume, and ran it for a number 
of hours keeping track of 
the duty cycle (it cycled because I was asking for more than the 
continuous torque rating).  The duty 
cycle was about 80%.  My calculations were between 800 and 1000 Watts 
electrical, and between 700 and 
900 watts mechanical for continuous use.  The only significant error was a 
tiny shaft mis-alignment 
which caused a pump bushing failure after a day or so, and the motor was 
putting out the power to 
burn the bushing too.  Pretty good.  More or less an honest 1 HP.  To give 
you the contrast to a current 
generation motor designed for an admittedly very short duty cycle, the 
Visteon (used to be part of our 
Ford group) gear drive starter motor used on most applications is 1200 
Watts input for 200 seconds, a 
pretty similar output but no where near continuous.  The GE has some real 
ratings, but they are on Bill's 
prints.  I asked once, but he didn't remember.

Larry Elie


-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu]On Behalf Of Markus Lorch
Sent: Friday, June 04, 2004 3:46 PM
To: 'Elec-trak list'
Subject: (ET) Mower motor strength requirements



With all the discussion about electric push mowers I am
curious how strong electic motors that drive one cutting
blade for push mowers need to be.

I know that small ICE mowers have around 3HP but I assume
that the B&D and Ryobi mowers have much smaller motors as
24V*18Ah should yield a max. of about 400 Watthours, prob.
even less as the batteries are probably rated at a much 
lower discharge amperage. Thus if these mowers run for 1 hour 
or so then I assume the motors are about 300W. Does anybody
know how strong the ET mower motors are (they drive a smaller
blade)

Also I assume the right cutting speed for such a mower is
around 3000 rpm (just guessing from the typical ICE speed).

Any insights?

Markus 


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