Electric Brake or Surge Brake?

[Benny K]

Just out of curiousity, does anyone out there know if the surge brake will lock up the wheels if the tow vehicle`s wheels are locked up in a panic situation?....you would think that they would, if the trailer was heavy enough since they basically duplicate the brake pedal operation of the brake system on the tow vehicle, or would the trailer weight itself prevent the brakes from locking up... ....something that I`ve never tried........Benny

[Pete Dumbleton]

Andrew, you're right -- Thinking about it, I can see that the surge brakes are essentially self-adjusting for varying loads -- Now that I'm thinking about it, I recall a very heavy boat trailer that my father had with electric brakes that was a bear to tow empty (without the very heavy boat) because the wheels would lock up with any medium application of the brakes -- That was back when the brake controller was hydraulic and tapped into the tow vehicles brake lines at the master cylinder.

Your point about non-working electric brake controllers is a good one -- Surge brakes are simpler and more likely to be actually working.

BTW, I forgot to mention that friction sway controls can NOT be used on surge brakes, according to the sway control manf.

[Brian B-P]

Just out of curiousity, does anyone out there know if the surge brake will lock up the wheels if the tow vehicle`s wheels are locked up in a panic situation?....

I've never towed with surge brakes, but here's how I see this situation:
The action of the surge brake system is unrelated to the behaviour of the tow vehicles brakes - it depends only on how hard the coupler is compressed, and that compression is [b]due to deceleration of the trailer.

If the rate of slowing down is extreme enough, then there would be enough brake action to overcome available traction at the trailer wheels, so if tug has sticky tires and big brakes, the trailer tires may not be able to match them, and slide.

If you panic and push too hard on the tug's brake pedal, the surge brake system can't "know" this; it can only brake hard enough to keep up with what the tug does. This seems like an inherently good characteristic to me.

Proper behaviour of the surge brake system depends on correct [b]design. The relationship between force at the coupler and braking force will depend on brake size and type, and the ratio of the slave cylinders in the brakes to the master cylinder in the coupler. An undersized master cylinder will mean excessive hydraulic pressure and thus too much trailer braking, and vice versa. Perhaps there is a mechanical leverage adjustment in some couplers, allowing tuning, but I don't know.

Cable-actuated surge (or "over run") brakes should have the same characteristics as hydraulic surge brakes, but it's an all-mechanical leverage issue, without hydraulic cylinder sizes to consider.

[Benny K]

Isn`t the tow vehicles severity of brake application also cause the trailer brakes to apply harder because of the inertia of the weight of the trailer being exerted on the plunger on the master cylinder of the coupler? The lighter the brake application of the tow vehicle, the less inertia being applied to the trailer coupler.....or am I in left field on this and not getting something?...man, how did I get into this? ...Benny

[Byron Kinnaman]

It appears to me that there's a couple of problems with surge brakes. One when trying to back a trailer up hill I would think the brakes would have a tendency to be applied. Another is the "panic button" thing. I've used the full brake lever once on my electric brakes. I don't know what would have happened with surge brakes instead of electric.

Another when backing with surge brakes, not uphill, there is no trailer brakes, if I understand how they work. With electric, prodigy controller, there's brakes.

[Bigfoot Mike]

I have been following this thread and there are [b]Opinions (not based on fact) and [b]Misconceptions.

There are reasons each type of trailer has different type of brakes.
There are Electric Brakes, Hydraulic Surge Brakes in both disc or drum, Hybrid Electric Activated Hydraulic and probably more. Most of the newer, better Boat trailer brakes seem to be made with Stainless Steel disc brakes, and are ALL surge brakes. They have an electric activated system (from the backup lights) for locking out the surge for backing up.

See “Hydraulic vs Electric Trailer Braking Systems” and scroll down to [b]Electric Brakes.

Electric brakes are commonly used in utility and RV trailers. In this application, their painted automotive grade components provide excellent service, if properly installed, wired and maintained. In boat trailer application, however, they fare poorly. The wet launch boat trailer application, especially in salt water, normally destroys electric brakes within a season or two.

Painted automotive grade brake springs rot, adhesively bonded shoe pads become detached from their foundation plates, and water soaked magnet electrical insulation commonly fails. For this reason, most boat trailer owners opt for hydraulic surge brakes either disc or drum.

[Bigfoot Mike]

...And the best of both worlds.
DEXTER Electric / Hydraulic Drum Brake Actuator

[Andrew Gibbens]

This reply applies only to European (mechanical) surge brakes - I don't know if it's relevant to US (hydraulic) surge brakes, though I doubt it.

One when trying to back a trailer up hill I would think the brakes would have a tendency to be applied.

No, nowadays all trailer brakes in Europe must be the 'auto-reverse' type which do not work in reverse, except when applied by the handbrake.

I think this law came about as you used to have to get out of the tow vehicle and lock out the brakes manually at the coupler - and I think too many people forgot to re-engage them before they drove off......

Incidentally, a British company has just invented an auto-reversing hydraulic disc brake, and I can't for the life of me think how they could work.

Another is the "panic button" thing.

This strikes me as the big advantage of electric brakes - and probably would be a bigger benefit over here where both trailer weights are heavier (relative to the tow vehicle) and noseweights (=tongue weights) are lighter.

However, I would be interested to know whether the 'panic button' function was only really of use to experienced drivers, who had the confidence to take a hand off the steering wheel to locate and apply the brakes - is this something novice drivers can do when a weave starts?

Another when backing with surge brakes, not uphill, there is no trailer brakes, if I understand how they work. With electric, prodigy controller, there's brakes.

This sounds a bit like the "not invented here" syndrome. I have never found the absence of brakes in reverse to be any problem - are there people who drive as fast or as aggressively in reverse as they do forwards?

My "not invented here" thing is concerning handbrakes - I can't for a moment understand how anyone could want the danger of a trailer with no handbrake.

I see Dexter offer electric brakes with a mechanical handbrake operation - has anyone ever seen these? They seem like the best of both worlds - though having dual operation they must also be the most expensive solution (and the cynic in me says that electric brakes would be promoted by trailer manufacturers as they are the lowest cost option).

Andrew

[Brian B-P]

Yes, Benny, I agree that that it's the braking of the tow vehicle which triggers the surge brake system - I was just pointing out that it doesn't matter how the tug brakes. The tug could slow down by engine braking, and it would still run the surge brakes on the trailer.

Electrically-triggered hydraulic disk brakes do seem like the ultimate in performance, and are used on very large RV trailers for that reason. They're about the only way to get electrical control and disk brakes together. As a system to tolerate immersion in water, the electrical hardware on the trailer would need to be mounted up high or sealed - not that this is a factor for our eggs.

The auto-reverse issues to apply in both hydraulic and cable systems. There is an auto-reverse drum brake design, which is also called a "free-backing" brake.

While the Prodigy (which I use) does act in reverse, it seems that some other acceleration-sensitive proportional electric controllers do not (which is why that is listed as a feature for the Prodigy). I agree with Andrew - this doesn't seem like a big issue to me.

I can be cynical, but I think I'm just being realistic when I say that I think electric drum brakes are standard on RV trailers only because they are cheapest - if they also work well, that's an accidental bonus. In my case, I considered going to the electric/hydraulic disk system, but killed that idea when I saw the cost, so I'm not criticising the trailer makers for doing the same thing. The handbrake, on the other hand, seems like a good idea for what should be a moderate cost - there's no more to it (even on an electrically-actuated drum) than an automotive handbrake with drums.