Ralph said,
"A while back
several people (including me) wrote in about the brakes grabbing when we tried
to slow down a little bit. Now I see it is the motor that is stopping
us. I have a steep hill in back of my house with no way to go around
it. The tractor speeds up going down, and when I touch the brake pedal I
slow down for about a foot then the wheels lock up. The tractor tears up
the grass and will start sliding sideways, very scary."
How many of you guys have the
brake switch adjusted to open as soon as the pedal is moved down ever so
slightly? I think this might be your problem.
Originally, I think GE wanted the brake switch to act as a
"kill the tractor in a panic stop situation", not every time you just barely
pushed the pedal down. I kinda looked at it as the "wife's
switch", as in when she wanted to stop but still had her right foot on the
speed control pedal on my WH C-185.
This scenario is even more likely when applied to the
large frame tractors with the dash mounted speed control. In an
emergency/panic like situation, it's a lot easier (and more natural) to mash the
brake pedal to the floor than to reach for the speed control lever on the
dash.
I may not remember our exact phone conversation all that
well as it was probably close to two years ago by now, but I think Steve
Richardson had his brake switch (on an E15 with dash mounted speed control)
adjusted "your" way because he never knew how it was supposed to be
adjusted. Check out Paragraph 1.15 BRAKE SWITCH ADJUSTMENT on page
1-24 of the Home Owner's Service Manual.
I personally think the brake switch should still be adjusted
to open just before the brake pedal bottoms out on the footrest. Try
it and I think your hill problem will go away.
Mike in KY
----- Original Message -----
Sent: Thursday, February 23, 2006 12:59
PM
Subject: Re: (ET) Alltrax install!
David Roden (Akron OH USA) wrote:
I have that very diagram right here on my computer. If you need a copy, you
can download it from here :
http://www.alltraxinc.com/old/Manuals/DCX-ET%20Manual.zip
Thats the same one I have. My old eyes didn't notice the power bypassing the main relay though the 1 ohm resistor
According to the diagram, those safety switches connect to the KSI
(keyswitch) input of the controller (6th pin from the left), not to the main
contactor.
Yes, but turning off one of these switches should turn off the B+ to the main contactor coil
Battery voltage on the KSI terminal enables driving current from the controller.
Any time the main disconnect is on, battery + is also applied to the 8th and
9th pins (designated logic B+ and B+ power respectively). These are
supplied from a tap *ahead* of the main contactor. The main contactor coil is
powered by an output from the controller, not directly by the keyswitch.
I thought the main contactor was connected to B- through a timer in the controller.
Those pins (8 & 9) are specifically intended to be powered *even when the
KSI terminal is not* so the controller can stop the tractor as quickly as
possible under the following circumstances -
1. the brake is applied
2. the keyswitch is shut off
3. the operator leaves the seat
It uses plug braking to do that. I have experienced this effect on my tractor.
If I want it to stop quickly, I just turn off the key or touch the brake pedal.
The braking effect is quite pronounced!
A while back several people (including
me) wrote in about the brakes grabbing when we tried to slow down a little
bit. Now I see it is the motor that is stopping us. I have a steep
hill in back of my house with no way to go around it. The tractor speeds
up going down, and when I touch the brake pedal I slow down for about a foot
then the wheels lock up. The tractor tears up the grass and will start
sliding sideways, very scary.
If yours doesn't behave this way, either you didn't wire it according to the
diagram, or plug braking has been disabled in your controller. I think you can
disable plug braking with the PC control program if you want to, but it's been
quite a while since I ran that program on mine, so I'm not sure.
I don't want to disable the plug braking on the seat and key switches, but I need a finer control of the foot brake. Do you think putting the brake switch in series with the throttle switch would allow the motor to coast then I could control the level of braking with the pedal and brake pads?
I may be wrong, but my understanding of plug braking is that it does not
actually apply reverse current. Rather it maintains the field current while
short-circuiting (or nearly so) the armature. This stops the motor very
quickly. If I'm wrong about that, I certainly welcome correction of my
misapprehension from the designers of the Alltrax, the designers of any other
plug-braking controller such as a Curtis, or those who have studied plug-
braking controller design.
I agree, but plugging means to turn yhe field on & off to control the rate of braking. To bad our Alltrax doesn't work that way.
Ralph
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