On Mon, 27 May 1996, wayne buletza wrote:
> Thanks for the advice regarding towing. I will get the car trailer rather
> than a dolly.
>
> As for the brakes...I was lead to understand that surge brakes were easier
> to use than electric. Help me understand the problems of one verses the
>other.
The surge brakes are easier to use, but they offer little control. The
surge brake system uses a link in the trailer tongue that is connected to
a master cylinder. When the tow vehicle slows, the trailer pushes against
the hitch and this force actuates the master cylinder which applies the
(hydraulic) trailer brakes. If properly set up, it works well for normal
stopping.
One hangup, though, is that if you try to back up hill, the trailer brakes
are applied. When you trailer horses to a show, it seems you always have
to park somewhere strange, like downhill with the nose of the truck
against a fence. Good luck getting back out. The biggest disadvantage,
however, is that you cannot apply the trailer brakes from the tow vehicle.
Sooner or later, a trailer will get loaded wrong, and start to whip back
and forth in a snake-like motion. This is scary as hell, and you can
steer all you want without stopping the motion. I have watched this
develop in a camper trailer in the NH mountains; the trailer eventually
whipped so violently its front corner dented the side of the car, at which
point the car and trailer went down a hillside and were destroyed.
I have had it happen to a horse trailer, because I had the wrong height on
the hitch. With an internal controller and electric trailer brakes, you
can apply the trailer brakes (but not the truck brakes) and it pulls
everything straight. I also like to apply the trailer brakes
independently on steep driveways. An internal controller also usually has
a control to adjust the gain of the trailer brakes to adjust for load; the
surge brakes to some extent do this automatically, but if a surge braked
trailer is over or under braked, I doubt you can change that easily.
Another respondant likes a controller that is actuated by the brake
lights of the tow vehicle. Unless there is something there that I don't
understand, it seems to me this would be an on/off system. I'd prefer a
system that applied the trailer brakes in proportion to the application
of the tow vehicle brakes. I tried a Sekonic electronic unit that used a
pendulum to sense the tow vehicle deceleration, and hated it. If the
sensitivity was set low, the trailer did not do its share of braking. If
it was set high, the trailer braked well on the level, but going downhill
the trailer could take over. I would apply the truck brakes, the trailer
brakes would go on, but because the slope affected the pendulum, the
trailer would brake so hard that releasing the truck brakes would not
have any effect and we would grind to a stop. The horse hated that as
did anyone behind me.
I finally got a system plumbed into the truck hydraulic lines, and all
was well. Applying the truck brakes applies hydraulic pressure to a
small slave cylinder in the controller and via a rheostat it adjusts
voltage to the electric trailer brakes. You can manually apply the
trailer brakes alone, and have an adjuster for sensitivity. With this, I
could set up the trailer as I drove so there was no feeling of being
pushed when I stopped, and the system worked perfectly whatever the grade.
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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