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Old 11-15-2005, 05:38 PM   #1
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Electric Over Hydraulic brakes?

Hi everyone,

This is my third attempt at posting this...sorry if it later appears in mulitples...


Has anyone done a serious comparison of the various electric over hydraulic brake units? I did a search on here but didn't come up with a whole lot.

I am redoing a '77 Excella and intend to switch it over.

From my own research, I've basically narrowed it down to either ActiBrake (which I understand Airstream is going to) or TowBrake. But I'm open to suggestion.

I did see on here where one fellow took a look at the ActiBrake and the Dexter and went with the Dexter.

From what I'm seeing, they all work in a similar manner. I read the Trailer Life comparison from last summer and it looked like about the best comparo I've seen yet. But, I wondered what you all had to say about the matter.

I think it's hard to argue with the ActiBrake, if Airstream itself has gone that route. As well, I understand that Inland RV has done testing of their own and that is also the unit they recommend. To me that means two good endorsements.

That being said, the TowBrake unit looks excellent. It works off a linear actuator which is basically a big servo. It doesn't get much simpler than that. As well I understand that it doesn't require any current except when changing pressure, so at a stop light when you push the pedal down, as long as you hold it down, you're not drawing any current. Only when you release does the actuator draw some juice to move the piston in the brake unit. The TowBrake unit costs more than the Actibrake though.

At any rate, thought I'd throw this out for everyone. Comments? Guidance?

Thanks,

Jim
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Old 11-15-2005, 06:42 PM   #2
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Jim,

I am the fellow who went with the Dexter. But I too had trouble getting much info off the forums on this. This is perhaps because there just isn't a lot of people doing this. Must of the trailers are electric brakes and many of the vac/hyd units that are being replaced are becoming electric units. It seems rare that somebody would maintain a disc brake system when it is cheaper to go with electric.

My actuator alone probably cost as much as a complete electric system including drums (note: I don't know if this true but I bet I am close).
That being said I wanted to keep the hydraulic system just because it's cool. But I did not feel as sure about the Actibrake as I did about the Dexter. Response time of the unit was the primary reason.

The Dexter is faster and runs at a higher pressure. In my case that already came into play during one harder than normal stop. The brakes easily locked up when I had the gain up a little too high. That to me means capacity to spare.

Having a 6 piston dual circuit pump doesn't give any extra margin of safety - if any one of the pistons lock up, the whole pump stops.

That is just my personal bias on this subject and not meant to dissuade anybody form buying something over another. it is just my thoughts on the subject and why I got what I got.

My comparison chart is here.
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Old 11-15-2005, 06:59 PM   #3
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Jim,

I don't have any data, but in my opinion a linear actuator will beat a piston pump every day. The only drawback I can think of is that 12V linear actuators large enough to do the job may not be small enough to make a compact actuator.

Of course a poorly engineered linear actuator system may be worse than a well designed piston system, but that's hard to tell from pictures.

In a few years hydraulic disc brakes calipers will be replaced with linear actuators. We need to wait for 42V power buss though. Then we'll be back to all electric brakes.
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Old 11-15-2005, 07:18 PM   #4
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Originally Posted by markdoane
. We need to wait for 42V power buss though. Then we'll be back to all electric brakes.
42V is on hold until the engineers can address the problem of arcing, and pitting of the contacts from the arcing.
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Old 11-15-2005, 07:34 PM   #5
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42V is on hold until the engineers can address the problem of arcing, and pitting of the contacts from the arcing.
Engineering problem with a solution.

Not so easy-getting Delphi out of bankrupcy.
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Old 11-16-2005, 09:37 AM   #6
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Linear Actuator

Well, I hope I didn't mislead about the TowBrake unit. It uses a linear actuator to push the piston on a standard automotive type master cylinder. So it is still using a piston and hydraulic fluid, but uses the linear actuator for muscle rather than vacuum. How this differs from any of the others I'm not really sure; I thought they all used an electric motor of some sort to operate the hydraulic piston.

I looked at rebuilding my old brakes, but what I'm seeing is it costs more to do that than to replace with new. So I plan to go the new route. Besides, some of the parts for the old (like the hubs) aren't even available anymore. Crack one out on the road and I'd be in trouble.

I considered switching to drums. It would be easier. But the numbers I saw in the Trailer Life article are hard to ignore. Basically the stock pickup stopped in 170', the pickup with the drum equipped trailer stopped in 350 feet, the pickup with the disk equipped trailer (same trailer, they retrofitted the disk kit to it) stopped in 200 feet. Man 150 feet could mean a lot. So I want to stay with disks.

Anyway, sorry if I misled anybody. TowBrake makes a big deal in their advertising of using linear actuators, and I have some experience with those in factory settings. Rarely ever had any trouble with one. Seemed like a good setup. The others may all use a similar setup and just not stress that in their advertising.

They are all pricey, so I wanted to research this as much as possible before making a decision.



Thanks,

Jim
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Old 11-16-2005, 10:40 AM   #7
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Jim,

You weren't misleading at all. I agree that a linear actuator makes a lot more sense than a piston pump; I wasn't aware that there was one available. Thank you for the information.

My only reservation about the linear actuator is that it must be fairly large to develop the pressure and speed needed. After reading more info about the Towbrake system I see that is true. But sometimes you need something large to get results. And it's only about twice as big as the 'pump' style units.

I read the Q&A this morning and I am impressed by the thought that went into the design.

All that remains is for someone to buy one and report back with real world results. I hope that someone is you.

The comment about linear actuators mounted directly on brake calipers to replace the hydraulic system is "blue sky" that may never reach widepread commercial use. Fun to think about though.
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Old 11-16-2005, 11:38 AM   #8
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Spec Correction

In my post above, I caught an error. I just reread the Trailer Life article at lunch (it's the February 2005 issue) and I quoted the stopping distance of the pickup itself wrong. It was 193 feet, not 170 feet. Sorry 'bout that.

But, that just shows how well the disk brake setup on the trailer works. It only took 7 feet longer to stop the entire rig than just the truck. And they said brake fade was nonexistent.

Disks for me

Oh yeah, the August 2005 issue has a comparison of the various Electric over Hydraulic units. But they didn't actually install them all in vehicles and really try them. More of a spec comparison.
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Old 11-16-2005, 03:26 PM   #9
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JimGolden

You may be trying to reinvent the wheel.

When you read reports from those that have used a certain setup or system, it is usally wise to heed their results.

If you wish to mix breeds or brands, just to perhaps save a few bucks, then you are on your own.

Keep in mind, that there is always "knock-off" parts and components available, but do they meet the standards of exhaustive testing? Usually far from it.

Exhaustive testing includes amoung other things, life expectancy, quality of construction, quality of materials, ease of repair when necessary, and the reputation of the manufacturer, who published the specs. Some companies are known to exaggerate specs or make rash promises in their warranties.

We did the research on Kodiak and Actibrake before Airstream did. They did ask us what we were using, how well they performed, and most importantly, how was any warranty handled. Perhaps that's why their using the same thing we are.

There are enough headaches in the RV business, without looking for ways to find some more. Treking out on an unknown highway for parts or components from knockoff companies is usually defeating.

We must keep in mind, that a knock off part or component is usually made with sub standard materials and/or workmanship. If not, then how do they manage to sell a seemingly equal part or component (their statements), at a far reduced price? Common sense says that's impossible. Ask those that have been there and done that, only to find out that when they bought "on the cheap" that is exactly what they got.

When it comes to certain parts or components, quality, safety and life expectancy all go hand in hand.

Andy
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Old 11-16-2005, 05:22 PM   #10
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Andy,

Are those comments directed at "Towbrake", or just any system other than Actibrake.
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Old 11-16-2005, 06:42 PM   #11
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markdoane.

My comments were not directed at any particular manufacture, be it parts or components.

It was however directed to those that may chose to combine different parts or compnents that have not been tested in a professional manner.

For an individual to combine different systems or components, is usually not a good idea, unless they can refer to professional testing, which takes time, energy, and at a considerable cost, as opposed to perhaps someones opinion, based on a short term, and usually without any factual parameters to report, other than, again, their personal experience. However, if that personal experience is over the long haul, such as years, then that becomes a different matter, but again if some meaningful facts go along with it, such as I recall you have done on numerous occasions, which I think is a very good thing to do.

If we keep in mind the new comers to our mutual interests, we must, at least in my opinion, refrain from sending them untired, unproven information, unless it's clear that it is indeed, ones short term opinion, as this site is open to all who wish to make helpful suggestions, as well as recommendations.

Granted, an individual can recommend anything, without assuming any liability. In California, if a business makes a recommendation, they can immediately become liable for it.

In that context, Inland RV Center, Inc., myself or it's staff, will only recommend the tried proven facts, and not opinions.

I hope this answers your question.

If not, please let me know.

Andy
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Old 11-16-2005, 06:49 PM   #12
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in summary

Basically, a "system" is better than a collage of parts put together, without any R&D to back up whast you are trying to accomplish.
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Old 11-16-2005, 07:09 PM   #13
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I don't think what Jim was considering was a cobbled together experimental "collage" system, anymore than attaching a Prodigy controller to a set of Dexter brakes is a 'collage of parts'.

It's a commercailly available system, even if it hasn't been around as long as Kelsey Hayes. The company has been making toad brake systems for several years.
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Old 11-16-2005, 07:14 PM   #14
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Originally Posted by markdoane
I don't think what Jim was considering was a cobbled together experimental system, anymore than attaching a Prodigy controller to a set of Dexter brakes is a 'collage of parts'.

It's a commercailly available system, even if it hasn't been around as long as Kelsey Hayes. The company has been making toad brake systems for several years.
Hmm, maybe I misread, I was in a hurry. What I thought I read was that some parts were going to be from manufacturer "A", and other parts were going to be from maufacturer "B". Let me know if this is not what was meant, I will delete my post so fast it will make its little electrons spin...
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