General Boards > General Discussion
Dinghy Brake System
Bill Sprague:
Until this topic came up here, I had given up thinking about it several years ago when I did a lot of thinking, reading and talking on the subject.
One of the things I read then was that automotive standards or practice require you to be able to steer and stop your car if the motor quits. So, I thought I should try it. It seemed logical because in Naval flight training the syllabus included knowing how to fly if the flight control boost system quit. I pointed the Subaru down hill on a section of I-5 south of Tacoma and turned the switch off. The steering got stiff and I had to push hard on the brake pedal to cause much deceleration. Although I didn't try it, a panic stop seemed out of the question.
While we were towing the Subaru we were also going to a lot of big rallies. I talked to everyone selling brake systems. When I asked about how hard their system pushes on a "dead pedal" the answers were either that it is user adjustable or it was designed to push the "right amount". One suggestion was that there is a "standard" that 70 pounds of force on a "dead pedal" would create the same deceleration rate on all vehicles allowed to be sold in the USA, regardless of their weight or brake design. I failed to find where that is written down.
I came to the conclusion that there was a lot of design and salesmanship with little real engineering or science in these systems. None seem to be reviewed or tested by any agency or association. Unlike our cars or motorhomes there are no design standards. There seems to be only creativity.
I also came to the conclusion that the only way you could ever "calibrate the proportional assist" would be to put a strain gauge in the motorhome receiver. With that you could determine if, during braking, the car was pushing too much or pulling too much during braking. Pushing would mean the toad brakes were not doing enough and pulling would mean the toad brakes are trying to stop the motorhome. I have not seen such a strain gauge for sale anywhere.
There are so many variables, that without such a gauge and measurement, there is no way to know if the "assist" is appropriate. And, and how could you know if the setting would get the assist correct for "normal", "aggressive" and "panic" deceleration rates.
As I posted earlier, I finally bought one when we bought a heavier car. I picked it because I thought it was the most simple system available. It has no settings and I have no idea if it pushes correctly on the pedal, if it is matched to Ford's version of a dead pedal or if it is matched to the weight of the car.
On edit, I would like to add that I have chosen to have one because I believe it is a better idea than to not have one. The intention of my "rant" is to express my frustration that none of these things provide a way to indicate their effectiveness or reliability. For example, I pulled the breakaway pin once and nothing happened. The next time, it applied the car brakes, but I have no idea if the force applied would stop the car or only slow it down a little.
Harvey Ziegler:
I have been reading this thread with interest and think about entering a comment.
I use a Roadmaster All Terrian tow bar and baseplates that I installed myself. I also use the Roadmaster Brakemaster braking system.
I would like to relay a inicident that I witnessed in the rear view mirror of the car I was driving at the time. About 20+ years ago I was traveling south on a farily major road in Calgary and just passed a gravel truck towing an empty 16' flat bed trailer and as passing noticed that his hitch was pulling off of the truck frame. about 2 miles further down the road I saw his trailer traveling accross the next lane no longer in the control of the truck. The trailer then jumped the curb and enter the median between the north and south bound lanes of traffic. As the traveled through the median the tongue of the trailer was throwing dirt in all directions like the snow would be thrown from a snow plow. It also hit a couple of street lamp standards as it traveled through the median shearing them off and tossing them through the air like match sticks.
The trailer then crossed both lanes of North bound traffic with out hitting anything and into the ditch which was quite flat. About 50or more feet from the edge roadway was a chain link fence which is what stopped this trailers travels but not until it had pulled out about 200 feet of fence.
Don't know if the truck drive even knew he lost his trailer as it was sitting beside me at the next traffic light.
Just something else to think about.
Gil_Johnson:
Here's a couple of examples of how break-away brakes saved the day.
I was towing an empty car trailer. After crossing a railroad crossing the trailer came off the hitch. The trailer's tongue was clearly visible through the back window of my Explorer. I didn't immediately brake, but rather allowed the trailer's break-away system to apply trailer brakes. The trailer's tongue hit the pavement and bounced while still attached to my Explorer by the safety chains. The trailer came to safe and uneventful stop under my vehicle. Without a break-away system I'm confident it would have went through the rear gate of the Explorer.
While driving across the Chesapeake Bay bridge, I was following a 1 ton truck pulling a small cement mixer. As he came onto the center span of the bridge he began to throw up some rocks. I moved to his left placing me in the far left lane. No sooner did I change lanes the cement mixer separated from its tow. It darted into my lane with its brakes applied. It hit the bridge's side rail and bounched back onto the road and stopped in the lane to my right. Had it's brakes not worked there's no telling what damage and injuries may have resulted on this highly travelled bridge.
As I've said before, I have a brake system on my TOAD more for the break-away system than anything else. FWIW, the Air Force One brake system does not push on a dead pedal. It has an air resevoir on the towed car to support braking and to supply vacum to the power brake booster.
Gil
JimCasazze:
We are about to begin our 1st "real" trip in a few weeks and this is the 1st time we'll have a toad (always carried the Harley in the past). I've been reading and considering the varying points of view on this thread attempting to reach some decision on what (if any) breaking system we will use.
Dick s: Thanks for your anaylis of the components and their likely failure possibilities. That helped me put things in perspective.
Joel W: I tend to agree with the KISS priniciple and like the surge brakes with simple cable mechanism. This would be themost likely way I'd go, except for the lack of breakaway prevention. As I tend to agree with Dick, that the odds of that happening on a reguarly inspected tow setup are within (my) acceptable limits - I may still go this route.
It is interesting to me to find that the few states (like Florida) where we happen to reside require breaks on towed vehicles when states that have real mountains like CO, MT, etc do not. Add to this the insanity of the triple tows you see here in FL on a daily basis, including cars being towed by ropes on the interstate and you have to wonder if there is any intelligence in this state.
We have yet to hook up the Grand Cherokee, but when it is delivered I will take it out for some test tows to deterime the effect on my PT's acceleration and braking.
I'm not sure what some of you refer to as a "Panic stop" as most times a car cuts in front of me and then slams on their breaks pretty much qualifies as panic to me. I try to mainain a minimum of 3 car lenghts (approx 60') per 10 mph of my coach velocity. Anyone that disturbs my buffer zone make me get uneasy as this 32,000 lb sled does not stop worth a damn compared to a passenger vehicle.
The GC weighs 5400 lbs so it does represent about 17% additional mass to stop. Will this be a linear breaking addative, meaning I will need 17% more distance to stop? I'm not sure what the stopping rate is. Perhaps I should go out to one of the old abandoned lots and test this. Hmm, I may do just that.
Another point that concerns me about the various systems out there was well put in an earlier post that talked about the lack of precise, engineering type information on exactly how much pressure (stopping power) these various systems acutally provide. I've read about every web page I could find on the subject and not one manufacturer provides any specific data in this area. While they all discuss the merits of their special, proprietary technology - none tell you they will provide ???? pounds of force, or ???% stopping power, etc.
In the end, I guess each system works to some extent and each has it's inherant weaknesses. Reading the ongoing discussions and real life experiances - That's what makes this forum so valuable. At this point, I think we may tow here in flatland for a bit and then decide a few hundred miles down the road if we need to address suplemental breaking.
J
Dick Simonis:
I've made the decision to replace my Even Brake system with a Ready Brake which is now on order. The simplicity off the ready brake and what appears to be an easy install appeals to my engineering side. It appears to be on of those things what will just work....no frill just works. Surge brakes have been around for decades and are truly proportional and better yet, automatically takes into account the weight of the toad. Plus a failure where the toad brakes are applied inadvertently is most unlikely.
As for the brake-a-way option, I'm looking at that but don't like the way it functions very much and am not convinced in the necessity. Once the Ready Brake gets here and is installed, I'll rethink this but a failure of the towing assy plus breaking both safety cables is tough to visualize.
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