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Re: (ET) Elec-Trak.org site...



Actually after one wheel loses friction with the surface you have NO braking.You know that Sir Issac Newton is in the driver's seat when you observe one of the wheels spinning BACKWARDS as you are sliding down the grade. {Watch for it some time. When it happens, there isn't much else you can do anyway.}

In order for braking to be effective, both wheels must have 'stiction' .If separate wheel brakes were available, after the weight transfer has occurred one outcome I can envision is a severe yaw resulting in an upset. :( Take your tractor down a slick enough, steep enough grade in 'L' or 'LL' and you can observe both rear wheels sliding as the tractor gains speed.At this point, it matters not how many brakes are attached where, if they are only present on the rear wheels.Seriously, try this experiment some time. You will approach hillside operation with an increased level of caution.

Small frame tractor operators can seek even larger thrills by using three twelve volt batteries in the front compartment only. :)

RJ

Pieter Litchfield wrote:
Not to belabor the point, but IMHO two wheel braking is always better than one wheel braking. The ET has, at best, one wheel braking.

However, your point about driving backwards is well taken. And we all know the mower deck works better in reverse than forward, so I guess that's more fuel for the fire!


On 3/23/2009 4:26 PM, RJ Kanary wrote:
You COULD try driving it BACKWARDS. The increase in weight transfer to the braking wheels is dramatic. <G> [BTW, enough velocity will result in lifting the front wheels AND the mower deck from the ground. }The root problem isn't braking effectiveness, it's just plain physics.On a downhill run, ANY rear wheel braking system is in trouble. It CAN'T be avoided.

RJ

Pieter Litchfield wrote:
One of the "problems" with my E-12 and E-15 tractors is that the disk
brake is attached to the transmission input shaft.  As such, it is on
the engine side of the transmission wheel differential.  Locking a well
adjusted brake is quite possible.  However, you are only locking 1 rear
wheel in doing so, and that would be the wheel with less traction.  I
can't tell you how many 1 wheel skid marks I have left down damp grassy
slopes around my house with the brake working as good as or better than
factory fresh.  I'd love to have brakes on BOTH rear wheels, especially
if I could use independent braking to assist turning or for traction
control when spinning under power.

By the way, if you leave it in a low gear and DONT touch the brake pedal
going down hill, dynamic braking by the motor is as useful as the brake
pedal.

But my main point here is that you can't put a dress on a pig.  The E
braking system can't be "fixed" to produce dramatic stops because of the
way in which it was engineered to begin with.




On 3/23/2009 1:33 PM, Christopher Zach wrote:
JS wrote:

Hi Chris,
I don't think this response will get posted since I am responding to
your email. Perhaps you could post if you think anyone else may be
interested.

Sure. I'll reply this to the list, good questions.


I am surrounded by steep hills, and find the brake system inadequate. It
requires frequent adjustment, especially seasonal. I was thinking of
some alternate braking arrangement; perhaps more regenerative (like my
Doran EATV). I suspect it does that to some degree already unless it
bounces me off my seat switch and cuts off the power, where I am left
more or less in what I call "free fall". Kinda scary the first time this
happened.

Oh yeah, the Elec-trak brakes are not great. There is an upgrade to the
E20 brakes that is "better", Harold Zimmerman has the details. I don't
mind the semi-annual adjusting, just make sure your brake disc can move
on it's axle as well as the brake caliper.


Anyway I noticed you mentioned NiCad batteries for your tractor. I
didn't know they could be used for this application. I need a set of
batteries (and possible charger-blows home circuit breaker five seconds after I plug in) for my Wheel horse C185. I've been swapping out from my
E12, and wonder if Nicads would be: 1) easier to charge and maintain
(and more readily adapt to small solar charger) and 2) provide more
power and more capable to recharge form small scale solar. Are they
available to purchase do they require a different charging system? What is their life expectancy? I have Makita power NiCD's that are over 25
years old, and still useable.

I use a set of sixty SAFT Nicds that are basically BB600 flooded NiCD
batteries. Each one has a 30ah capacity at 1.2 volts. The Elec-trak
charger isn't perfect, but it does seem to charge them pretty well.

The problem with NiCDs is that they are not as efficient as lead on
charge, but they're still not bad. The big advantage is capacity does
not go down based on current draw, so my 60ah pack can provide 60ah even
if I'm running the snowblower up hill in zero degree weather. They are
not affected by cold either. On the downside they are lighter, so the
tractor is lighter (on a tractor, weight is good).

In the winter I stick on an external weight box that has another 30
cells for blowing tons of snow. I can probably fit 30 more up front in
place of the old T105's, but that weight thing is still a problem.

I have 250 of these cells in my S10 truck, and I am thinking about
pulling them from the truck and selling them. While they are great and
last forever the truck needs some more range and charging a string of
250 in series is harder than charging strings of 30.

Chris


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