Types of brakes that comes on AS

[davidachoi]

I still haven't picked up my 1976 27' Overlander, yet, since it's not ready. But I wanted to know how many braking systems comes on these trailers. I was told that they only came with the emergency brakes that are applied when the trailer and tv become separated. But I'm reading other threads about Prodigy brake controllers, but those are only controllers, right? That would mean that the brake controller is controlling another brake system? I'm confused with the whole breaking system right now. Can someone shed some light on this subject for me? Thanks.
David

[n2916s]

Your trailer, unless it has been modified by a previous owner (unlikely) has electro-mechanical brakes. They are powered from the tow vehicle which must be equipped with a brake controller of some type. The Prodigy (which I have) is a reasonably priced inertial controller that is activated when you step on the brakes. It then measures the rate of decelleration and provides an appropriate amount of current to apply the trailer brakes proportionately.

In a trailer seperation scenario, the breakaway switch activates and applies full current from the trailer battery to the trailer brakes, hopefully bringing it to a quick, safe stop.

You never want to have the breakaway switch activate while the trailer is attached to the tow vehicle as the current reversal will smoke the controller. If you are going to test the breakaway, make sure the plug to the TV is pulled.

Trust me when I tell you that you do not want to pull a 27' trailer unless the brakes are operational.

mike

[azflycaster]

Most Airstreams came with electrical brake systems. The same components that are used for the emergency braking are used for normal braking. You will need a brake controller in your truck to activate the brakes during normal braking. The Prodigy (I use one) which has been updated to the P-3 is a very good controller and probably the most popular one on the market.

[dwightdi]

Some of the mid 70's trailers came with a vacuum assisted hydrallic disc brake system. It was difficult to maintain and many were changed over to the electric brakes as I did to mine. You still needed a brake controller module in the truck/van as well as a vacuum line leading to the back of the TV if you wanted to use the vacuum assisted power disc brakes.

[davidz71]

Originally Posted by davidachoi

I still haven't picked up my 1976 27' Overlander, yet, since it's not ready. But I wanted to know how many braking systems comes on these trailers. I was told that they only came with the emergency brakes that are applied when the trailer and tv become separated. But I'm reading other threads about Prodigy brake controllers, but those are only controllers, right? That would mean that the brake controller is controlling another brake system? I'm confused with the whole breaking system right now. Can someone shed some light on this subject for me? Thanks.
David

You might also have the Hydra-vac system which used huge disc brakes instead of drums. I had that on my '77 Excella 500 and did see a '78 Overlander that had been converted from Hydra-vac discs to electrical actuator which powered the hydraulic disc system. With the Hydra-vac system, upon receipt of an electrical signal from the brake controller on the tow vehicle, a synchronizing valve shuts off a vacuum supply line from the tow vehicle (usually manifold vacuum) and allows air into one side of a vacuum booster power diaphragm. This exerts force on the booster hydraulic cylinder which generates the hydraulic pressure needed to activate the disc brakes. Contrary to those who do not understand the system, it is a much better braking system than any drum system out there. The problem is finding someone who will work on the system. One way to eliminate that problem is to eliminate the need for the vacuum line from engine manifold to the rear of the vehicle by buying a brake activator which is electrically operated yet fulfills the mechanics necessary to apply hydraulic pressure to the disc brake lines. You could remove the entire brake booster system mounted in front of the trailer behind the propane tanks and put the small brake actuator in it's place. The disc brakes left are then so much easier to work on than the drums of today. You may not have the Hydra-vac system on your trailer, it might have been converted with the brake actuator or it might have been converted over to electrical drums.

[Goin camping]

Davidachoi,

I wanted to welcome you to the Forums and invite you to join in on any and all Calstreamers rallies. (camping trips.)

Good luck with your new trailer and make sure you have brakes on it.

[davidz71]

David,
If you find that the trailer has electrical drum brakes, take a good look at their condition. My '86 has the original round brake magnets and the braking has not been as good as I have liked. On a recent trip to VA., a brake spring broke and the shoes made contact with the drum. Friction turned the drum bright red with resuloting heat burning off the bearing lube. The inner bearing failed, tore a chunk out of the drum hub and then the tire blew. This resulted in $271 worth of brake work on that axle, $107 for a new tire and $2200 worth of wheelwell damage after the part of the tire went through both outer and inner fenderwells. This didn't include the over $300 worth of gasoline to drive to the factory in Ohio to have the fenderwell replaced by the experts.

The star adjuster at the bottom of the drum brakes has been the culprit for many a drum brake failure. Find out how long ago the brakes were serviced and see that someone checks them out thorougly when you get home. If the shoes need to be replaced and you have the round magnets, I'd replace the brake assembly on each axle. It's actually cheaper in the long run than having someone just replace the shoes and springs.

[davidachoi]

Thanks, everybody for your input. I will have to talk to my guy about making sure I have sufficient braking power and get a Prodigy for it. One more question, then. Do I need a weight distribution system if I, more or less if I can keep 10-15% of the trailer weight on the hitch? If I can keep that much weight there by not putting junk in the back or making sure all tanks are empty before moving, then I may not need a WD system, right? I just want to keep this towing system as simple as possible.
Goin Campin, I'll join your group once I get my trailer.

[davidz71]

Originally Posted by davidachoi

Thanks, everybody for your input. I will have to talk to my guy about making sure I have sufficient braking power and get a Prodigy for it. One more question, then. Do I need a weight distribution system if I, more or less if I can keep 10-15% of the trailer weight on the hitch? If I can keep that much weight there by not putting junk in the back or making sure all tanks are empty before moving, then I may not need a WD system, right? I just want to keep this towing system as simple as possible.
Goin Campin, I'll join your group once I get my trailer.

David,
I'd use a weight distribution system. You didn't state what your tow vehicle is but unless it is a one ton dually then I'd use the WD. You never know what might happen should you have to make a quick stop or swerve to miss something in the road (like a couch I almost hit on the interstate). Make sure you know exactly what type of brake system this trailer has before you go to pick it up. If it is the Hydra-vac, you will need to do some plumbing for the vacuum system before you leave.

[dwightdi]

There is a critical design flaw in the old disc brakes caliper holders. They welded in the slide pins into the machined plate steel mounting brakets. The had only a minimal thickness of metal to work with. The brakes put large amounts of torque on these pins. The result is the welds start to fatique crack after about 50,000 miles. It is difficult to see where they start to crack. Once the crack grows big enough, a complete failure can occur when you apply the brakes in an emergancy situation. That is what happened with my 77. Brake parts all over the road and no braking power because the failed pins allow the caliper to come loose and rip out the hydrallic lines. When I took all of them off the next week, I found fatique cracks in 4 of the 6 remaining pins and the pins were starting to work loose. I am a graduate mechanical engineer and I would never design a product like. I replaced the brakes with the electric drum brakes. They do not stop the trailer as well as the discs but atlest the stop the trailer reliably. I hope the design of the new disc brakes is better as they are made by another company.