RE: (ET) Solid state controls

["Phil Trice" <pctrice purdue edu>]

Steve,
        They're both good ideas, but probably a bit beyond my ambition. 
The tractor
I have
has a differential installed, and I'll likely keep it. I'd like to have
independent brakes
on the rear wheels, but don't have room on the tractor to implement it.
        What I thought I might do to increase manuverability to something
approaching ZTR
is the following:

1) Shorten the wheel base. Mine has a belly-mount deck; I'll move it to a
front-mount, and make the wheelbase about 2.5" shorter.
2) Move from two-steered wheels to a single wheel, centered under the
tractor.
3) Because of (2), I will make it a steer-by wire. Probably a joystick,
driving a stout
        little stepper motor. One external motivation to do this is a bad 
case of
        Carpal-Tunnel syndrome. (After a couple of hours behind the wheel, 
my hands
are
        pretty uncomfortable.)

        How's this sound for a summer project? :-)

        -Phil Trice



-----Original Message-----
From: owner-elec-trak cosmos phy tufts edu
[mailto:owner-elec-trak cosmos phy tufts edu]On Behalf Of SteveS
Sent: Tuesday, July 23, 2002 1:48 PM
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) Solid state controls


I can see two ways to do it:

First is how my old Allis-Chalmers (and most old tractors) allow 
zero-radius
turns; independent brakes on each rear wheel. By stopping (or slowing) one
wheel the differential shifts all movement to the other wheel.

The second (and more interesting), would be separate electric motors on 
each
rear wheel. This would allow turning about your center by having the rear
wheels turn in opposite directions - Wheee!

Either of these methods would be simpler and more efficient, I think, than 
a
hydraulic solution.

Interesting ideas....... Dang day job keeps getting in the way!

SteveS
E12S




----- Original Message -----
From: "Phil Trice" <pctrice purdue edu>
To: "Christopher Zach" <czach computer org>; "SteveS" <ssawtelle fcc net>;
"Elec-trak" <elec-trak cosmos phy tufts edu>
Sent: Tuesday, July 23, 2002 2:31 PM
Subject: RE: (ET) Solid state controls


> Chris,
> I'm in agreement with most of what you said. What I would like
> to achieve, and what I have found usefull in the past, is the
> *functionality* of the hydrostatic transmission. Has anyone used the
> Dixon ZTR mower, or one like it? They also use the hydrostatic
transmission,
> but use two levers to control direction & speed of the rear, driving
wheels.
> The front wheels are, in fact, uncontrolled casters. The net effect
> (after a bit of a learning curve) is a very manuverable machine.
> One of my goals is to implement some of that efficiency of control in
> an electric tractor. Rather than hand controls, I plan to use a single
pedal
> to control direction and speed. In another reply, David Roden (Thanks,
> David)
> referred me to the British-made 4QD controller. I checked it out on their
> website, and it looks like it might be a very good solution for what I
plan.
> All of the motors I'm using are PM type, so the controller will work
without
> modification. The only thing I'm short on with this project is 
> time-aren't
> we all?
>
>
> -Phil Trice