sisu1a wrote:
Electrics are still more flexible as well as
more reliable. Why more reliable, well I know for sure that my
electric brakes work. How do I know? I can test them, for ALL
functions and responsiveness, throughout their entire performance
range. As far as I know the only tests for surges are 1. put on the e-
brake, does it roll? 2. Get trailer/tow vehicle up to speed. Give a
firm application to the brakes. Did you feel the trailer first push
into the vehicle before pulling on the hitch?

My Cobra acts differently:
* mild brake application - we just slow down
* more brake application - a little bump as the surge brake begins
braking the trailer
* me, the car, and trailer begin slowing down more quickly, but there is
no evidence the trailer is *pulling* on the car - it's just not pushing
as hard.

(that's got to be good
for the car) I suppose thats all there is you can test them for, since
they are a binary system. on or off.

Not on the Cobra trailer, which has "proportional" brakes - the harder
you brake, the more the force is applied to the trailer tongue, which
applies more force to the brake shoes, which adds more retarding force
to the trailer. It is definitely not an ON/OFF system.

Electric brakes ALSO work automatically too
of course, according to the level you set them to (which to reiterate
can be easily adjusted WHILE driving).

Why would I want to adjust the brakes? Why aren't they set correctly
from the start? I've never felt the need to adjust the brakes on my Cobra.

I fail to see how a
thermal will affect me while driving,

A strong thermal can be very upsetting, because the winds are going in a
small circle that don't affect the tow vehicle and the trailer in the
same direction at the same time. Strong thermals can make my 11,000
pound motorhome towing my 2400 pound trailer deviate as much as a 20+
knot cross wind when coming out from behind a "cut" in a hill, and they
aren't as predictable. I don't drive over 60 mph except for passing, and
I can assure you the combination is dead stable at 90 mph, so it's not
like I'm close to the safe limit.

Perhaps the effect is very vehicle dependent.

Why do you think engine braking is hard on the engine and transmission?

Because you are putting load on it, load that is frankly quite
avoidable. Load = wear, period.

Well, yes, but it's a pretty light load, I think. It's just the pistons
sucking against a closed throttle during the intake stroke, and only the
tiniest power pulse (if any) on the power stroke, so the load is far,
far less than when the rig went up the hill with a lot of throttle, just
minutes before. If you want to reduce wear, slowing down slightly on the
upside is going to make a much bigger difference than using engine
braking on the down side.

I choose to put the load/wear my
brakes as opposed to major drive train components. The loading of most
braking is WELL within the safe tolerances of these systems.

I don't think it's a bad plan, and if your brakes can handle it, it's a
reasonable choice. What can happen is the brakes overheat before the
driver has enough warning to do something about it. I prefer to risk the
extra net wear on the vehicle than to experiment with the limits of
the braking system.

Besides, I have no reason to believe pressing the "OD" button to lock
out 4th gear on my motorhome, Camry, or mini-van causes them significant
wear when going down a hill; in fact, the newer models of these vehicles
(last 3 or 4 years) will automatically do that for you while on speed
control.

Naturally the car manufacture is
NOT going to caution you against ruining expensive parts they are more
than happy to sell you.

Except for that pesky warranty... Basically, I agree with you: short
hills, brakes are fine; long hills, down shift and use the brakes
sparingly. Don't "ride" the brakes, is what I was taught, and I think
it's still good advice.

While I agree that you may not need
brakes at 5mph, I can imagine cases where they might be nice to have,
albeit rare.

So rare, that after 200,000+ miles of towing glider trailers, I still
can't think of a single situation.

No, I do not mean while backing down a hill. I mean when your trailer
is trying to overrun the tow vehicle while you are driving down a
steep enough hill and you had no idea your brakes were engaged for an
entire down grade-until you got to the bottom and smelled it-or a
wheel fell off etc. It was this very phenomenon that initiated my
original post on the subject some time back.

I've never noticed that. It might be because the Cobra trailer has a
pressurized shock absorber in the surge mechanism that prevents the
brake from applying unless there is significant force on the tongue.
This means it takes more than a gentle stop to overcome the pressure in
the shock absorber before the brakes will apply, and likely prevents the
brakes from applying when going downhill, unless it's quite steep.

Tell me again why it's an advantage to keep a battery and charger in the
trailer, instead of none at all, like my surge brake system.


Because then you have a battery/charger in your vehicle. It is nice to
have emergency 12v power when and if it were needed. A lot of things
could be powered off that battery in a pinch.

How big is this battery? Can't the tow vehicles battery be used to power
stuff in a pinch?

Best of all, you can
splice into the charging circuit and use it to keep your plane's
batteries topped off if you hook solar panels up to it.

You don't need a battery in the trailer to do that - just hook up a
solar panel and regulator that connects to the glider battery. To
reliably charge the glider in time for the next day will take a much
larger panel than one suitable for keeping a breakaway battery charged
up, so I don't see a savings there.

Hmmm, now that
I think back, weren't YOU looking for a solution to keep your solar
panels from frying batteries a little while back?

Yes, and the problem I had (improper regulator) would have fried the
battery the trailer depends on for it's breakaway duties.

I know I'd REALLY miss the parking brake on my 2400 pound trailer, but I
could get along without it on a 1600 pound trailer.

With electric brakes you have a battery/charger in the trailer (sound
familiar?). This is intended as an emergency breakaway backup and has
a pull switch on the tongue. Although it is not intended as an e-
brake, that is essentially what it is. If you ever needed to use the e-
brake to man-handle the trailer, it is actually quite easy, but the
manufacture does recommend against using it in perilous situations.
There is also the drawback that you have limited time with this action
(Federal minimum for battery is 15 minutes of full locked brakes), but
that seems like it should do just fine for any grunt work you may need
to accomplish, particularly if you have chocks too.

That might work. The situations I had in mind would likely take only
5-10 minutes to resolve (and the brake wouldn't need to be applied all
that time,either), and then the trailer would be hooked up again or the
chocks would be in place.

that does not circumvent the fact that electric
brakes can outperform surges-as far as the action of braking is
concerned- in both stopping power and most certainly in finesse. There
is a reason electrics are the most common type of brakes in horse
trailers; they can be used smoothly but firmly if needed, but with an
amazing degree of control and usable adjustment range.

Is the reason the electric brakes need all this adjustment (in horse
trailers, for example) is to compensate for the large differences in
braking action required between a loaded and unloaded trailer? A surge
brake system automatically compensates for load variations, an ideal
situation in a trailer that might be 1700 pounds loaded and 1000 pounds
when the glider is out of it.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

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