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Author Topic: Towed brake connection, serious safety and legal issue  (Read 3292 times)
Jerry Liebler
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« on: August 29, 2007, 11:08:43 AM »

I have a Brakemaster 9160, by Roadmaster that I've installed in what will soon be my towed.  This is an air cylinder that activates the towed's pedal and it has a 'breakaway' reservoir and switch.  It connects to the coach by a single air line through a 'quick connect' fitting.  The installation instructions tell one to use an extra port on the rear brake relay valve to supply the quick connector, or if no extra port put a 't' into any of the lines that has air flow only when the treadle is pushed.  There is no mention of any form of 'tractor protection' and I believe there is a federal law making it a crime to hook up a trailer without.  In the event of a break away, the towed would have it's brakes applied but the bus, on the other hand would have a 1/4" tube draining it's air so braking would be severely limited.  I sure don't like this situation.  I looked into tractor protection valves but they all depend on the trailer's connection by a supply/emergency line and a control line.  Since they sense reduced pressure on the supply line to shut things down they won't work with the Brakemaster's single line.  Then I found  http://rversonline.org/ToadInstall.html
Neat. by adding a relay valve and a pressure protection valve at least 85 psi of bus air will be available for braking even if the towed breaks away.  The 2 valves add less than $100 to an already expensive system.  I'm adding in an r4p pressure protection valve (85 PSI) and an r-12p relay valve to the installation and think anyone who doesn't add similar parts is taking a huge unnecessary risk.
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Jerry 4107 1120
 
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« Reply #1 on: August 29, 2007, 11:16:22 AM »

Hi Jerry,

I think members here have mentioned that this kind of brake needs to be tapped from the tag axle to not

disrupt the drive axle brakes. But, if you don't have a tag axle, what do you do?  Huh

Nick-
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« Reply #2 on: August 29, 2007, 11:54:55 AM »

Great article. I wish I had known about it ten years ago. That was always one of my main worries about that same braking system that I installed back in the 90's. The other problem that I saw was that it was difficult to do a static test of any kind to see it it was actually working.

And Nick, if you disrupted the braking of the tag axle, then you would defeat the purpose of this system, since the tag axle does a significant amount of braking also. At one time my tag axle pressure was not adjusted properly and I could see my tag axle tires smoking during hard stops. Needless to say, I got that corrected promptly as it made flat spots on the tags. LOL
Richard
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« Reply #3 on: August 29, 2007, 12:21:59 PM »

Alternately, couldn't a breakaway cable and pin be installed on the bus and connected to the toad... sort of the reverse of what the toad has?  When / if the toad breaks away, a solenoid or some mechanical spring-loaded valve would cut the air to the toad brake connection.  It seems like this might be much easier to install, cheaper, and possibly more reliable.  Of course, if a line connecting the toad to were to rupture, this system wouldn't help.  If an electric solenoid valve were used for the breakaway, the rear air connection could be disabled from the driver's seat.  I guess this would be just a trailer air control, but it would also be automated in the event of a break away.

David
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« Reply #4 on: August 29, 2007, 04:00:32 PM »

  I have been thinking about this also.  Our present system is an M&G brake unit that fits between the vacuum brake booster and the master cylinder on our Grand Cherokee.  It is operated by air from the tag axle brake line. I also installed a small air tank (4" x 4.5") under the hood of the Cherokee. It is tied into the air line from the bus tag axle brake through a Tee, check valve and a solenoid. I also installed a pressure switch on the M&G. This pressure switch controls a flashing LED on the dash of the bus. Anytime the M&G is applying the brakes, the LED Flashes.  When we connect the toad, part of our pre-trip check is to make a hard brake application and watch M&G flashing LED to confirm toad brake application.  This also pressurizes the tank for break-a-way operation.This serves 2 purposes. First, it lets me know the brakes are working. Second, if the break-a-way cable should catch on something and activate the solenoid, applying the brakes, the flashing LED will let me know the Cherokee brakes are being applied. Hopefully, if that should happen, I will see the Flashing LED and stop, preventing a toad fire from an overheated brake.
    When I installed the M&G, I filled the tank to 40 PSI, temporarily connected a toggle switch to replace the break-a-way switch and drove down our road at about 45 MPH. Put transmission in Neutral, let loose of steering wheel and flipped the switch. Brakes did not lock, but a very quick stop in a straight line. Did this 4 times off the little tank before there was not enough pressure to apply the brakes.
   I have thought about installing another solenoid (N.O.) in the read of the bus. The wire from this solenoid would go through a break-a-way switch installed under the bus rear bumper and connect to the toad with a cable (similar to the break-a-way switch on the toad).  My biggest concern was finding a solenoid the could handle 85 PSI (max brake application pressure I can generate with hard service brake application) and have a large enough orifice. When the brakes are released, all the air to the M&G has to vent back through the bus tag axle brakes.
   As far as smoking the tags, I have under HARD braking (darn quick traffic lights!).  I have noticed tags never lock up with less than 40 PSI brake application pressure. Normal braking is 10-20 PSI.  I have though about installing a pressure regulator in the line to the tag brakes limiting tag brake pressure to 30-35 PSI.  Jack
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« Reply #5 on: August 29, 2007, 04:34:01 PM »

I don't have a tag axle or a sure mental picture of how one would be 'plumbed' so I'm unsure if this solves the problem.  The thought of another breakaway system, kind of in reverse occurred to me as a way to use a 'big rig' tractor protection valve I dislike it because it would require a pneumatic break away device that would be new and different.  I also considered the solenoid valves but they aren't certified for use in air brake systems & might cause legal problems if I somehow had to go through a DOT inspection.  A beauty of the solution with the pressure protection valve and relay valve is these are both certified air brake components.  I'm sure it also will work with Jack's system Too.
Regards
Jerry 4107 1120   
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« Reply #6 on: August 29, 2007, 06:20:23 PM »

Jack, my tag axle tires smoked because the torsalastic on the tag needed adjusted to put more weight on the axle. This is how I found out it needed done. LOL
Richard
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« Reply #7 on: September 01, 2007, 11:18:46 PM »

Jerry,

I am not any sort of tecnichian on this subject..... but i installed a product called Air Force One by a company called SMI... I beleive it has the necessary connection to block off the air on both the bus side and toad side... it has a quick disconnect on a the controller box which attaches to the bus - on the disconnect they suggest you cover the connector with a little black plastic cover - after unhooking the toad i have forgotten to put that little cover on - and no air pressure is lost... the toad has that reserve air tank and its own controller as well... just a thought - i am sure you already have a fortune invested in a setup - but maybe this will give you some ideas. just do an internet search on smi or air force one brake controller.... I bought it because I liked how small the acuator was for inside the toad and that once it was installed you can't even see it inside of our jeep liberty. 

Also - the method for install on the bus (1989 Eagle 15) was to hook up to the service line on one of my air canisters. I installed a tee on that line and ran my air hose from there... very straight forward installation.

For what its worth.... just some added info.

John
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Jerry Liebler
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« Reply #8 on: September 02, 2007, 06:31:48 AM »

John,
   Yours ,I think, is really the same set up as I'm talking about.   Sure the female quick connector blocks the air flow when it's taken apart 'properly'. BUT  what happens in a breakaway is the tubing will either break or pull out of the connector, leaving an open air line.  This ABSOLUTELY will reduce the coach braking ability.
I've talked to Roadmaster and they insist it's still safe.  How do they know how safe MY bus is in this case.
I strongly believe they haven't been sued only because breakaways are very rare.    By adding the pressure protection valve and relay valve I know that I'll still have 85 PSI.
Regards
Jerry 4107 1120
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Jerry Liebler
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« Reply #9 on: September 02, 2007, 06:44:17 AM »

Well after looking at the SMI 'Air Force 1. They certainly claim the coach air is 'shut off' in the event of a break away.  No details but definitely the claim.  Regards
Jerry 4107 1120
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JackConrad
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« Reply #10 on: September 02, 2007, 07:02:06 AM »

Jerry,
    Are you saying the relay valve and pressure protection valve are standard air brake parts?  Do you have Bendix part # for these items?  Jack
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« Reply #11 on: September 02, 2007, 07:48:45 AM »

Jack,
    YES, they are standard air brake system components.   I'm using a Bendix R-12P relay valve and a PR 4 pressure protection valve.  At this moment I only have the pressure protection valve in my hands, its PN is BX286500B1  When I get the relay valve (I just ordered it) I'll post it's actual PN as well.
Regards
Jerry 4107 1120
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« Reply #12 on: September 02, 2007, 07:55:03 AM »

Great discussion this one!

Some thoughts:

tapping into the existing bus air system needs to be done in a way that maintains air pressure balance and timing. Tapping into one service line will significantly delay the application and release of the brake that has added mileage to its plumbing. You need a relay valve with sufficient ports to assign the toad its own.

You definitely need to have an automated way for the air system to protect itself from a rupture of the toad plumbing.

For connecting the two vehicles, maybe just use gladhand couplers like the truckers do, mounted correctly so they pull apart instead of tear the guts out of the install, in the case of a break away?

You may also add the second dash mounted plunger and the tractor protection valve for the pain of running one airline from front to back.

From a liability standpoint, mimicing a tractor trailer install would be easiest to defend, and raise less eagerness on the part of an enforcement officer to challenge your install. If they recognize the bits, they won't think to get suspicious?

But there is not nearly the fun in "rolling your own" by going with conventional strategies.

As a sometimes "smoker", (oh, but I don't inhale... Wink)I do like the pressure protection/relay valve concept.

If you cut the toad airline, as long as air stops leaking out the cut line sometime soon, and the coach has enough air pressure left to stop properly, and of course, the poor toad has a realistic chance of stopping itself, and you didn't build it out of McDonald's straws, good for us! A bonus would be having a way of verifying the performance of the toad brakes while underway, but that's sounding too much like a tractor trailer set-up again....

Maybe convention isn't that bad?

happy coaching!
buswarrior
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« Reply #13 on: September 02, 2007, 08:00:51 AM »

I have had the Brake master system and don't feel it's ability is poor on power brakes. As you know when there is no vacuum the force required to push on the brake pedal is large and from my use it never feels like the toad is doing much brakeing. Jerry
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Jerry Liebler
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« Reply #14 on: September 02, 2007, 08:11:55 AM »

Here is a link that states the law.
http://www.cvsa.org/resourcecenter/documents/2005_02_tractor_protection_systems.pdf
As I read it a commercial vehicle towing a towed with the brakemaster system installed according to the maker's instruction would be placed out of service if inspected.  What I'm installing still doesn't fully meet the stated requirements as they include ability to activate the 'trailer' emergency system from the cab.  But it certainly does meet the safety issue.
Regards
Jerry 4107 1120
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« Reply #15 on: September 02, 2007, 08:53:10 AM »

For the loop hole lurkers...

First, let's remember, in the civil courts, the letter of the law is rather meaningless when there are better solutions available and one chooses not to be responsible and employ them.... So don't be purposely dumb when you can be smarter? anyway, that's not the discussion I'm starting...

CVSA is an organization tasked with ensuring consistancy in inspection procedures and defining out of service criteria between all enforcement officers across all the jurisdictions of the US, Canada and eventually Mexico. They are NOT involved with the statutes that the various enforcement officers use to lay charges in their own jurisdictions. You want to review the actual statutes that may apply to you, where you live, and whether you have concern regarding reciprocity with the jurisdictions you travel through, or whether you must comply with each jurisdiction's rules.

bus conversions aren't commercial vehicles, so legally speaking, they all go out the window.

what were the regulations at the time your chassis was built?  Many bus chassis being used as conversions pre-date much of the regs about these trailer/air system matters.

The base highway traffic act/motor vehicle act/whatever, in your jurisdiction will contain some basic motherhood standards. That's about the only ones that will be legally able to be applied against you.

Unless you give them the chance to define you as a commercial vehicle... best to know intimately the various definitions of that, because there are more than two, if you conduct any business activity out of or by way of the coach, or claim some bus expences as business related on your taxes... good luck!

Remember a motivated liar-for-hire will be coming after you....

Well, if you want to play the game, and bend the rules, you best know the rules intimately, and the book is pretty thick!!!

From a moral standpoint, and peace of mind, I'd suggest that it is reasonable and relatively easy and inexpensive to have your toad perform according to the latest commercial regulation expectations.
What does a tank of fuel/inverter/generator/refrigerator/ice makerair conditioner/Webasto each cost? Toad braking system can be put together for far less than much of what we spend money on.

That would be above and beyond the law, something your lawyer will be able to use in your defence!

happy coaching!
buswarrior
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Jerry Liebler
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« Reply #16 on: September 02, 2007, 09:18:03 AM »

Buswarior,
    The Federal motor vehicle saftey standards, quite specifically CFR 49 571.121 do not exempt RVs or bus conversions, regardless of age, and clearly require, in S5.1.3 protection of the (air brake equiped) towing vehicle's air pressure in the event of any failure in whatever is towed. It simply makes sense to live within this law. How or if it's ever enforced, who knows.
Regards
Jerry 4107 1120
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« Reply #17 on: September 02, 2007, 09:49:54 AM »

I'm wrestling with the same thing.  Pulling my 3,750lb car, it still does not put my rig over the 36,000gvw it is rated, so my braking even with the towed is within design specs (with towed I weigh 34,750lb).  What I want to protect is break away.  Installing a truly second air circuit duplicating what semis have is the best, then if you loose trailer braking, the bus braking will be unaffected.  It makes me nervous just to tap into the relay side of the braking system to provide the air pressure for the air cylinder on the towed.  And on mine, it would be a floor mounted air cylinder that is removable since the air cylinder between the master cylinder and the brake booster is not available for Mercedes.  Hopefully someone will do an install with a suitable solution.  Good Luck, TomC
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« Reply #18 on: September 02, 2007, 11:09:57 AM »

Tomc,
    The roadmaster system adds several things for 'break away' protection.  A check valve, a small reservoir, a solenoid valve, and a breakaway switch are added.  The instructions tell you to begin your trip with several hard applications of the brakes.  This is to pressurise the reservoir through the check valve.  I in the event of a break away the solenoid valve will be actuated by the towed's battery and the breakaway switch, this will pressurise the air cylinder from the reservoir.  The problem is that the same breakaway has left the coach air brakes with a 1/4" tube blading the coach air. 
Regards
Jerry 4107 1120
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« Reply #19 on: September 02, 2007, 12:01:04 PM »

My suggestion would be to look at the hydraulic couplers on the back of a farm tractor. They have been using a simple break away protection system for the last fifty years.
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« Reply #20 on: September 02, 2007, 02:15:44 PM »

A bonus would be having a way of verifying the performance of the toad brakes while underway,

    When I installed the M&G unit on our Grand Cherokee, I added a 3 PSI N.O. pressure switch at the M&G unit.  Anytime the M&G is activated, the feed from the pressure switch activates a flashing red LED on the dash. Part of our pre-trip is to make a hard brake application and check the flashing LED to make sure the M&G is working. This hard application also fills the emergency air tank on the car for break-away protection.
  In the event the break-away switch should accidentally be activated by the break-away cable catching on something, the flashing LED will warn me (and hopefully prevent a possible brake fire).
   When I installed the M&G, I did a test by putting 40 PSI in the emergency tank and temporarily replacing the break-away switch with a SPST switch. I drove down our road at 45 MPH, transmission in neutral, let loose of the steering wheel and flipped the switch. Nice firm stop in a straight line. The small tank allowed several test stops before running out of air. 
    When I made the break-away cable, I connected the car to the bus, including the safety tow cables. I then unhooked the hitch and pushed the car back to the end of the safety cables. I made the break-away cable about 3" shorter than this length. Hopefully I will never find out how well this works, but in the event of a break-away, the Cherokee brakes should apply just as the safety cables become tight. If this happens as planned, the coiled air hose should have enough slack that it will not break. If the Cherokee leaves the bus, I am not sure how that broken 1/4" air line will affect bus braking.  Since we live out in the country, I may try a test. I can insert a male quick connect fitting in the toad brake connection on the rear of the bus and drive down the road.  When I apply the brakes, with a 100-125 PSI pressure in my air tanks, I can see if I have plenty of air to stop. Mind you, I would consider this a "quick emergency stop".  If I get a chance to do this next week, I will post the results.  Jack
« Last Edit: September 03, 2007, 06:33:36 AM by JackConrad » Logged

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« Reply #21 on: September 02, 2007, 05:01:02 PM »

There was a similar discussion some time ago here:http://www.busconversions.com/bbs/index.php?topic=3413.0
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« Reply #22 on: September 03, 2007, 12:02:25 AM »

Hello Jerry.

First, I agree with you completely in the moral imperitive to protect our fellow man from harm, and work on my bus conversion accordingly.

But on the legalities,

Wrong body of law,
You don't get charged under the federal motor vehicle safety standards, you are charged under your jurisdiction's motor vehicle code/highway traffic act and those related regulations in relation to operating the vehicle on the road in some inappropriate manner.

FMVSS is for the design and manufacture of the vehicle, which we aren't doing, applicable as of the date of manufacture. For instance, we do not have to retrofit older equipment to meet the newer standards. For instance, lots of us with single circuit brakes, many of us with no spring brakes.

We are maintaining and modifying an operating vehicle of some vintage.

happy coaching!
buswarrior
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« Reply #23 on: September 03, 2007, 05:34:24 AM »

I'm not going to address the legal issues, just the practical. If a 1/4" line to the toad was ruptured it would have a very minimal impact on the braking of the bus. One of the reasons for using air brakes on heavy vehicles is the fact that a blown line or diaphram won't affect the system to a great degree. I have blown several air lines and diaphrams in my career, even have driven with the trailer valve wide open, and it really made no difference to the stopping ablility of the truck. The only big effect is that it will deplete the air supply if the pedal is depressed for a long time at low RPM. Then it will use up the air supply.All that said, do I think it a good idea to have protection for the bus air supply? By all means Would I install it on my bus? yes. The point is that a ruptured toad air line will only blow when the brake is applied, and even then not enough to cause a major braking problem.   Donn
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