RE: (ET) Re: new electrics

[Rod Hower <rodhower ameritech net>]

Hyster, Yale, Toyota and Linde are going all AC
across the board on their forklifts in the near
future.  This will provide a good source for low
cost motors and controls for riding mowers.
I've even seen 24V walkies with AC induction systems.
The major players in the motor control market
are Curtis, Zapi and SME (Toyota makes their own).
Rod
www.qsl.net/w8rnh

--- William Korthof <wkorthof earthlink net> wrote:
> The cheap batteries have been around for quite a
> while...
> golf cars have created this market: a pack of six
> US2200
> or T105 batteries cost just a few hundred dollars
> (~$300).
> 
> I think the improved power electronics and motor 
> choices
> (in volume, a 3-phase inverter is cheap enough to
> allow
> use of 3-phase AC motor). An AC motor driven by
> normal
> vector drive inverter obviates the need for multiple
> gears.
> Regenerative braking is also easy with AC drive. All
> the
> above would result in significantly improved
> efficiency vs
> GE Electrak-era hardware.
> 
> Any necessary 12vdc accessories can be operated
> directly from a DC-DC converter. Lighting and
> markers
> could use LEDs and compact fluorescent lamps.
> 
> Todays power electronics also make it easy to have a
> powerful automatic charger that is "plug and play"
> to a
> standard outlet and provides most of a charge within
> 2-3 hours. Faster, smarter charging, improved
> efficiency,
> and more completely balanced battery discharging
> (vs electrak taps) would lower the AC power use,
> extend
> run time, and lengthen battery performance and pack
> life.
> 
> In addition, todays inverters could easily provide a
> nice
> supply of 120 VAC for portable power tools.
> 
> I do think that a modern electric tractor is an
> unexplored
> product with a significant un-served market.
> 
> 
> /wk
> 
> 
> At 09:46 AM 2/20/04 -0500, Elie, Larry (L.D.) wrote:
> >Hydrostatic is 65 to less than 80%, depending on
> many factors including 
> >temperature.  It's used on gas tractors for
> connivence, nothing 
> >more.  Hydrodynamic (car automatic) can go much
> higher, but isn't really 
> >variable speed at all; just shift-on go.
> >
> >It's always funny when our 30 year hindsight
> realizes that people 30 years 
> >ago weren't dumb.  If electric tractors rise again,
> it will be because 
> >someone has a cheap battery or ultra-cap... or
> perhaps uses a cheap fuel 
> >cell.  This market is already poisoned, and no
> large marketing guy will 
> >touch it.  Once business people 'know' that no one
> will buy something, 
> >they stop trying.  Another example:  Diesels have
> 50% market penetration 
> >in Europe at higher fuel price.  In the US it's 5%,
> because GM failed 
> >marketing it in 1980, and now everyone 'knows' that
> no one will buy 
> >them.  Service is part of that.  They tried, but
> not well.  People paid a 
> >large premium to buy the early ones, and then
> averaged over $1,000/year 
> >for repairs.  I'm afraid Honda or Toyota may poison
> the electric market 
> >for the next 25 years too.  If they start passing
> on real their costs, 
> >they will indeed kill the market.  I'm glad GM
> pulled out before they 
> >poisoned the electric market.  No one will take
> large los!
> >  ses for long before they pass them on or pull
> out, and pulling out to 
> > give others a chance is the BETTER choice for
> everyone else.
> >
> >Larry Elie
> >
> >
> >-----Original Message-----
> >From: Ralph & Elaine Vogan
> [mailto:ralphgv centurytel net]
> >Sent: Friday, February 20, 2004 3:33 AM
> >To: Elec-Trak
> >Subject: Re: (ET) Re: new electrics
> >
> >
> >Does anyone know the efficiency of a hydrostatic
> drive?  Use a single speed
> >motor and the drive for forward, reverse, and speed
> changes.  I have an old
> >White ice tractor with a very small hydrostatic
> drive unit bolted to the
> >differential.  It has plenty of power.  Or a
> hydrolic pump & motor to drive
> >the blades?
> >
> >Ralph V
> >
> >
> > > With all this talk about new ETs and better or
> cheaper ways to make them
> > > please remember that due to the limited energy
> storage on board our
> >tractors
> > > efficiency must be paramount.
> > >
> > > V belt drives tend to be only 90-95% efficient
> when everything is in good
> > > condition and clean.
> > >
> > > Friction drives are 80-90% efficient.
> > >
> > > Chains, again in good condition, are 98 %
> efficient, but high maintenance
> >to
> > > keep them in good shape in a tractor
> application.  Notice that they are
> >not
> > > used except in high torque attachments like the
> snowblower.  A worn, dry,
> > > and/or rusty chain can have efficiencies as low
> as 60-70%.  The wasted
> > > energy turns to heat and destruction of what is
> left of the chain and
> > > sprockets.
> > >
> > > Direct drive, like the mower decks, are 100%
> efficient.
> > >
> > > GE used VX series V belts for the traction motor
> because the VX series V
> > > belts are more efficient than the old A/B/C/D
> series V belts.  If the new
> > > Poly V belts, which are like the serpentine
> belts on modern cars, had been
> > > available when the Elec Traks were designed they
> would have been used
> > > preferentially over VX belts.
> > >
> > > What GE did was make a whole series of design
> choices to keep efficiency
> > > high.  Where they lost efficiency was in the
> motor controls, and that was
> > > mainly a limitation of affordable DC drive
> technology of that time.  If
> >you
> > > were, in your new tractor, to use a friction
> drive for the traction motor
> > > and belts in the mower deck, and then allowed
> for lack of maintenance,
> >you'd
> > > find extra losses of 10-25% after 1 or 2 years
> of service.  I mean 10-25%
> > > higher losses than in a tractor with direct
> drive to the blades, and a
> >high
> > > efficiency belt somewhere in the traction drive.
> > >
> > > With respect to protecting the mower motor with
> a circuit breaker:  This
> > > will not work well with a permanent magnet
> motor.  In permanent magnet
> > > motors there is some critical armature current
> above which you will
> > > demagnetize the magnets.  The friction washers,
> while crude, act as a
> >torque
> > > limiting clutch.  By limiting torque, you
> effectively cap the armature
> > > current.  If you use a circuit breaker alone the
> current can, and most
> > > likely will, pass well above that critical
> current before the breaker
> >trips.
> > >
> > > Steve Naugler
> > > snaugler earthlink net
> > >
> > >
> > >
> > > _______________________________________________
> > > Elec-trak mailing list
> > > Elec-trak cosmos phy tufts edu
> > >
>
https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak
> 
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