Re: (ET) Elec-trak Digest, Vol 14, Issue 109

["David Roden" <etpost drmm net>]

On 27 Aug 2016 at 22:38, Christopher Zach wrote:

> Sure, but if you constantly go from forward to reverse you start burning 
> up
> the contactors.

No, not at all.  If you're using an Alltrax (or almost any other 
electronic 
controller) you have only one contactor, a main one for master power.  All 
the motor current is managed by the controller's silicon.  

There's never any of the arcing that used to trash the reversing relay my 
E15 used to have.  I sure don't miss those days.  I fitted the Alltrax at 
least 10 years ago, and I haven't had to open any of the ET's access 
panels 
since.

To reverse the tractor, the controller silently and electronically 
reverses 
the field.  Everything is done under control of a microprocessor.  If you 
reverse your ET with the "throttle" on (which I usually don't do), it 
gently 
reduces the armature and field current to zero, reverses the field, and 
then 
re-applies the previous armature and field current settings.  Basically, 
it 
does what you probably should have done yourself.  :-)

It also has a spooky "hill holding" function that will apply power to 
actively hold the ET still when the potbox is at zero.  This makes me a 
little more uneasy than the "active reversing" above, so I prefer using 
the 
good old fashioned mechanical brake.


David Roden - Akron, Ohio, USA

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