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Discussion Starter #1
I am converting my John Deere L111 Riding Lawn Mower from ICE to
all-electric. There are a couple of design considerations and I would
greatly appreciate recommendations and comments from the Group. I think your
help and ideas will save much time, money and, above all, frustrations.

My design criteria's are:

1) It must operate very much like it originally did, or else my Chief
Operator (wife) will not be happy ... and you know how that goes.
2) Because of above, I believe it is best to stick with the hydrostatic
transaxle, even recognizing the inherent losses. I think I can live with
that. The hydrostat is very simple to operate, with no gear shifting or
switching to go from forward to reverse.

At this point, I plan on using equipment on hand:
> Advanced DC motor 140-22-4001A
> Curtis 1204X-4407 (24-36 VDC) Not 100% sure about this one.
> Six 6-volt Golf Cart Batteries ... not yet acquired. (operate at 36 V)

Preliminary design is to mount the motor, vertically, above the transaxle
input drive shaft and directly couple the two units together, through an
appropriate coupler. This design has been "mocked up" and appears to be do'
able. (See blog link, below.)

Here is where I need s little help:

The rotational direction of the motor is opposite from what is required with
my proposed arrangement. Since the motor is single-ended, I would need to
reverse the motor direction.

QUESTION ONE: Is running the motor in the reverse direction possible? I
assume some changes need to be made ... and what are they? Can I do this
myself or should I send it to a motor shop to have it done? Can any motor
shop do it?

QUESTION TWO: The hydrostatic transaxle should operate at around 3000 rpm,
continuously. Obviously, the DC motor speed could vary from runaway over
speed, with no load to some undetermined lower speed under heavy load. Is
there a controller, or some other way, to control the motor speed,
regardless of load, to around 3000 rpm, say +/- 200-300 rpm within limits of
the power available, of course. There is a multi-bladed cooling fan that is
between the motor and transaxle. (I have a piece of reflective tape on one
blade to use with my optical digital tachometer.)

Any and all help and suggestions will be GREATLY appreciated.

Roger Daisley
Pullman, WA
[email protected]

http://ElectricTractor.blogspot.com

http://ElectricVW.blogspot.com



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Registered
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70 Posts
Discussion Starter #2
Roger.
The equipment you list needs a fairly constant load for speed regulation
of the motor, the original gas engine had a built in governor to maintain
constant speed. you would find it simpler to regulate the speed if the motor
was a Parallel wired unit but that would require a different kind of
internal field winding. (Thinner wire, many more turns of wire..) a local
motor shop might sell you a suitable motor and accept yours in trade. then
you will only need an on/off control as the motor tends to run a single
speed. alternatively, use what you have and add an accelerator pedal and the
operator can use audio clues as most drivers will do reflexively to maintain
the rpms at optimal levels. Mostly it would require lifting the pedal to
shift and pressing it down to run.
Motor rotation can be reversed by reversing the wiring to the field OR
the brushes/armature that is why most motors we use have four terminals and
a jumper connects two together just move the outside jumper to the other
terminal on one end and it will run the other direction. HOWEVER to make
motors more efficient the brushes are moved from the centered position to
up to 15 degrees of advance. if they are centered the motor runs in either
direction well but if set up in advance only one direction runs much better
and the other shows a lot of brush arcing and runs much less efficiently.
have a motor shop check the motor timing and if not at centered, reverse the
brush location by removing the brush guides from the end support and
reposition them for rotation in the other direction, DO NOT SKIP HAVING THIS
DONE or you will have problems.
Alternatively, if you mount the motor in front of the trans-axle and
connect it with a belt drive you can raise the motor rpm to about 5,000
which is a more efficient speed for it, and by mounting it shaft end up the
rotational direction difficulty is cured with out any modifications needed
which is a cost savings because two pulleys of say 10 inch and 6 inch and a
"V" belt will cost less than a motor shop labor charge, if the motor must be
higher use a jack-shaft with pullys on both ends and a pair of pillow blocks
to hold the shaft.
To summarize mount the motor in front of the trans-axle with a belt
drive to give the motor higher rpm for more efficiency and better internal
cooling, use the motor controller to regulate the motor rpm with feedback
from the accelerator pedal and operator skill,(Tell the wife to use it like
the speed pedal on her sewing machine.)
I hope this helps...
* Regards,
Dennis Lee Miles .COM
[email protected] <[email protected]>
Phone: 1 (863) 944 - 9913
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++*

Roger Daisley <[email protected]>wrote:

> I am converting my John Deere L111 Riding Lawn Mower from ICE to
> all-electric. There are a couple of design considerations and I would
> greatly appreciate recommendations and comments from the Group. I think
> your
> help and ideas will save much time, money and, above all, frustrations.
>
> My design criteria's are:
>
> 1) It must operate very much like it originally did, or else my Chief
> Operator (wife) will not be happy ... and you know how that goes.
> 2) Because of above, I believe it is best to stick with the hydrostatic
> transaxle, even recognizing the inherent losses. I think I can live with
> that. The hydrostat is very simple to operate, with no gear shifting or
> switching to go from forward to reverse.
>
> At this point, I plan on using equipment on hand:
> > Advanced DC motor 140-22-4001A
> > Curtis 1204X-4407 (24-36 VDC) Not 100% sure about this one.
> > Six 6-volt Golf Cart Batteries ... not yet acquired. (operate at 36 V)
>
> Preliminary design is to mount the motor, vertically, above the transaxle
> input drive shaft and directly couple the two units together, through an
> appropriate coupler. This design has been "mocked up" and appears to be do'
> able. (See blog link, below.)
>
> Here is where I need s little help:
>
> The rotational direction of the motor is opposite from what is required
> with
> my proposed arrangement. Since the motor is single-ended, I would need to
> reverse the motor direction.
>
> QUESTION ONE: Is running the motor in the reverse direction possible? I
> assume some changes need to be made ... and what are they? Can I do this
> myself or should I send it to a motor shop to have it done? Can any motor
> shop do it?
>
> QUESTION TWO: The hydrostatic transaxle should operate at around 3000 rpm,
> continuously. Obviously, the DC motor speed could vary from runaway over
> speed, with no load to some undetermined lower speed under heavy load. Is
> there a controller, or some other way, to control the motor speed,
> regardless of load, to around 3000 rpm, say +/- 200-300 rpm within limits
> of
> the power available, of course. There is a multi-bladed cooling fan that is
> between the motor and transaxle. (I have a piece of reflective tape on one
> blade to use with my optical digital tachometer.)
>
> Any and all help and suggestions will be GREATLY appreciated.
>
> Roger Daisley
> Pullman, WA
> [email protected]
>
> http://ElectricTractor.blogspot.com
>
> http://ElectricVW.blogspot.com
>
>
>
> _______________________________________________
>
>


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