On Tue, 28 May 1996, Chip Old wrote:
> I was the "another respondant". That's what you get for opting for a
> Sekonic controller instead of a Kelsey-Hayes. The latter is pretty much
> standard equipment among horse towers in my area and enjoys a very good
> reputation. The unit is activated by current from the brake light switch,
> and braking force is modulated by the internal pendulum which senses both
> gradient and deceleration. The Sekonic and all others I've seen work the
> same way.
>
> If the controller is connected correctly and if the brake light switch
> works correctly, there is power to the controller and therefore power to
> the rheostat/pendulum assembly and therefore
> braking at the trailor only when you apply the tow vehicle brakes. If
> yours continued to brake the trailor after you took your foot off the
> brake, then either the unit was installed incorrectly so it always had
> power, or your stoplight switch was defective, or the brake shoes on the
> trailor were not retracting, or you're one of those people who rides
> around with his foot always resting on the brake pedal. :-)
I don't want to prolong this forever, but maybe it is of interest to some
on the net who plan to do some towing. For you car people, though,
smoothness may not be as critical as it is for horse towing--any sudden
moves throw the horse off balance.
Chip is right. I definitely wired the Sekonic so it had power all the
time, but unless I am badly mistaken, that's how the instructions said to
install it. I can't check any more, because I took it out and threw it in
the trash. Now that you mention it, it would sure have worked a bunch
better if it had been hooked to the brake light. Hmmmm.... I am
generally good at following instructions, but maybe...
Nevertheless, I want to make one last argument in favor of the
hydraulically actuated electric brake controller (and I did end up with
one from Kelsey Hayes). I think the principal advantage of the
"electronic" controller is ease of installation, because they need only
electrical connections. I do think they have drawbacks, and only
experience can tell you if you can live with them. If I had powered the
Sekonic electronic controller from the tow car brake lights, it would have
eliminated part of my problem, but not all of it.
If the trailer brakes are powerful enough to be really effective, they
will affect the deceleration of the truck and trailer. That is, of
course, what they are intended to do. If you use an electronic/pendulum
controller, I would expect (and experienced) the following. Apply the
tow car brakes, which causes deceleration, which is sensed by the
pendulum, which applies the trailer brakes. The trailer brakes cause
further deceleration, which moves the pendulum forward, which applies the
trailer brakes, which causes further deceleration, etc. This, I
think, would happen no matter how the unit receives power, though
having it powered by the brake lights lets you stop the vicious
cycle by removing your foot from the pedal, whereas I sometimes
just ground to a halt. But it does not seem like a system that would
give you smooth braking and absolute control.
I expect the electronic controllers can work fine for many people, if one
or all of the following conditions apply: 1) they set the trailer brakes
light enough that they help, but the tow vehicle still does most of the
stopping and the trailer does not have much impact on the deceleration; or
2) their trailer has only 2 wheel brakes that can't do much more than
assist in stopping no matter how the controller is set; or 3) their tow
vehicle is so much heavier than the trailer that the trailer doesn't
constitute a big additional load.
I prefer to have the trailer brakes do virtually all of the work of
stopping the trailer. The hydraulic Kelsey-Hayes system lets you modulate
both the truck and trailer brakes by your pressure on the brake pedal,
with independent adjustment of the proportion of braking power provided by
the trailer. Try one, Chip, you don't know what you are missing.
Ray
Ray Gibbons Dept. of Molecular Physiology & Biophysics
Univ. of Vermont College of Medicine, Burlington, VT
gibbons@northpole.med.uvm.edu (802) 656-8910
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