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Re: [EVDL] Gizmo EV "gearing"

Thanks Cor,

I wondered about that but after talking to D&D motors
a few minutes ago I don't think I'll hit that hard max
RPM. The guy I talked to said there shouldn't be a
hard max rpm, but then he didn't think I had a 3:1
gear ratio either. He didn't like my 30T drive gear to
90T wheel gear way of determining ratio. I told him it
shouldn't matter since the same cogged belt had to
match up on both gears so the tooth pitch had better
be the same. Any way, he said that I should be getting
to 4600rpm and 7ft-lbs of torque at the top end at
48V.

Below is the response I received from Mark Murphy,
after reading his reply I'm wondering if I should add
one more 8V battery and see what happens. It looks
like the controller can be set to accept a slightly
higher voltage but I may be asking for trouble if I
do. The maximum cutout _low_ voltage setting is 48V
and the maximum cutoff _high_ voltage setting is 75V.
Maybe if my DC-DC converter will handle 56V input it
would be worth a try. Any ideas?


--- Mark Murphy <[email protected]> wrote:

> From: Mark Murphy <[email protected]>
> Subject: Re: Gizmo EV "gearing"
> Date: Mon, 27 Aug 2007 22:16:42 -0700
> To: "David D. Nelson" <[email protected]>
>
> Hi David,
> With the BugE we use a 5.5 ADC series wound motor
> with a 6-1 gear ratio
> ( on a 20" diameter wheel) My Gizmo is similarly
> geared using a ADC
> 6".6 series wound motor.
> Both are 48 volt.
>
> My experience is that you need a 24 volt rated
> series wound motor but
> run it on 48 volts.
> I don't think you need a larger motor,, you may need
> lower gearing and
> higher RPM.
> if your motor is rated at 48 volts, run it at 72,
> but don't increase
> the weight of the battery pack.
>
> You can always install a fan for the motor.
>
> Belts are quiet, but usually require a lot of belt
> tension and pressure
> on the wheel and motor bearings. A chain is noisy
> but is low drag.
>
<<<<<snip>>>>>
==========end of quote==========

--- Cor van de Water <[email protected]> wrote:

> Since the motor is SepEx, it will have a hard max
> RPM limit
> which depends on voltage.
> You can easily use a larger gear ratio to reduce the
> torque
> (and thus amps) that the motor needs to sustain, but
> the
> drawback is that you have to increase the voltage to
> reach
> the same max speed, or accept that your max may drop
> well below
> 40, likely even below 35.
> This can also be solved by rewinding the motor and
> keeping
> the same pack voltage - the choice is yours.
>
> Success,
>
> Cor van de Water
> Systems Architect
> Proxim Wireless Corporation http://www.proxim.com
> Email: [email protected] Private:
> http://www.cvandewater.com
> Skype: cor_van_de_water IM:
> [email protected]
> Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD#
> 25925
> Fax: +1 408 731 3675 eFAX: +31-87-784-1130
> Second Life:
>
www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of
> David D. Nelson
> Sent: Monday, August 27, 2007 3:08 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Gizmo EV "gearing"
>
> Thank you for all the ideas coming in on this.
>
> I just sent Mark Murphy an email so I report back
> what I hear from him. I have thought for a while
> that I needed to figure out a way to do some forced
> cooling.
> I am pushing this motor to its max when I climb. The
> brushes showed evidence of arcing from the brush
> holder to the sides of the brush. I don't know if
> this happens only when the motor is hot (higher
> resistance) or at any time. The armature current
> routinely goes over 300amps during my hill climb.
>
> David
>
> --- keith vansickle <[email protected]>
> wrote:
>
> > david
> > have you emailed Mark Murphy at Blue sky design he
> is in creswell
> > oregon and originally built these veh kEVs
> >
> > --- Jeff Major <[email protected]> wrote:
> >
> > >
> > > Hi David,
> > >
> > > You might want to consider forced ventilation on
> > the
> > > motor. Sounds like your performance is O.K.
> Just that your duty
> > > cycle is too hard.
> > >
> > > Increasing the gear ratio will lower the load on
> > the
> > > motor and slow down the top speed of the
> vehicle.
> > > That would likely make the motor run cooler, but
> take you longer to
> > > get where you're going. I'd try keeping the
> same ratio and blowing
> > > a lot of clean air thru the motor.
> > >
> > > Regarding the larger motor, you'd probably have
> to retune the
> > > controller.
> > >
> > > Jeff M
> > >
> > >
> > >
> > >
> > > --- "David D. Nelson" <[email protected]> wrote:
> > >
> > > > Hi all,
> > > >
> > > > I have a Gizmo EV (www.nevco-ev.com) which has
> a
> > > 48V
> > > > pack and a 6.7" D&D Separately Excited Motor.
> I
> > > have
> > > > run it for a year but the hill climbing I have
> > to
> > > do
> > > > has started to burn up the motor. Jim H has it
> > > right
> > > > now to rebuild/repair. We had been considering
> installing a 7.5"
> > > > motor to see if it would
> > handle
> > > > the
> > > > workout I give it a little better.
> > > >
> > > > I decided to do some calculations to see what
> > rpm
> > > > the
> > > > motor was spinning and here is what I found:
> > > >
> > > > Speed : tire rpm : motor rpm
> > > > 10 : 171 : 514
> > > > 20 : 343 : 1029
> > > > 30 : 514 : 1543
> > > > 40 : 686 : 2057
> > > > 50 : 857 : 2572
> > > >
> > > > What I am wondering is if I can change the
> > gearing
> > > > to
> > > > get a better than a 3:1 ratio maybe a 6:1
> ratio
> > > will
> > > > I
> > > > still have the same top speed? Right now my
> top speed on the level
> > > > is about 44mph. Jim, and I think he said Tim,
> thought that maybe
> > > > the existing motor would handle my needs if
> the motor spun at a
> > > > much
> > > higher
> > > > rpm.
> > > >
> > > > My next question is, does any one have any
> suggestion as to where
> > > > I might find some replacement gear/pulleys?
> This is a belt driven
> > > > vehicle
> > which
> > > > has
> > > > the "teeth" in a V shape like this:
> > > >
> > > > \\\\\\
> > > > //////
> > > >
> > > > including the gap in the middle. The belt is a
> GoodYear Eagle
> > > > W-1280. I also need to know what
> > > the
> > > > smallest drive gear I can safely use. The
> > current
> > > > one
> > > > is 30 teeth. The one on the drive wheel is 90
> > > Teeth.
> > > >
> > > > I have attached 3 pictures. (I hope this
> doesn't violate list
> > > > rules.) It appears that there are
> > two
> > > > sets of bolts which bolt the gear/pulley on
> the wheel.
> > > > One set bolts to the wheel hub, then there is
> an aluminum adapter
> > > > which then bolts to the gear it self.
> > > > There isn't much room to go larger with the
> > > wheel's
> > > > gear since the belt would interfere with a
> > > support.
> > > > I
> > > > think I could go to a 115 tooth at the wheel
> so
> > if
> > > I
> > > > could go as small as a 20 tooth drive it would
> > be
> > > at
> > > > a
> > > > 5.75:1 ratio.
> > > >
>
>
> David D. Nelson
> [email protected]
>
>
>
>
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