Hydraulic fuses for brakes

[tarnx]

Hello Gentlemen and Ladies and I hope you are.

I was studying the single line braking of the M35b2. When I worked on aircraft they had a fuse for the individual brake lines going to each wheel. This was in case you lost pressure on one of the brakes in use. They are velocity sensitive. If a hose blew that would allow the fluid to travel faster as there would be no resistance. I believe you could insert one for each axle. That way if an axle blew a hose you would only lose that axle instead of both rears. They have both automatic reset and manual. The manual one might be best as you could at least have some brakes to move it to somewhere you can work on it.

At present I am not familiar with them as far as pressure, price, or trip speed. You would also have to know the kinds of fittings they would require to connect. I am out of time on my internet use. I don't know if it can be done or issues if it would. Add you interest.

 

[winfred]

i snagged this bookmark a while back http://www.vonberg.com/catalog_detail.html?partID=51 not sure of effectiveness or sanity of use on a road vehicle

 

[tarnx]

Well they work on airplanes. I suppose it is an argument on no brakes or partial brakes. I was just thinking about it as a possible solution to a single brake line problem. I blew out the lines on a VW bug at fifty five in a panic stop. I took the shoulder and hit a berm. I passed the car in front of me three foot in the air. The old VWs lose if they hit a raccoon. I was surprised that there was no damage to the car. Due to its age the brake lines rusted through without my knowledge. The outsides looked fine. The rust was internal.

 

[VPed]

Those fuses are for hydraulic system with significant fluid reserves. I doubt they would work properly in this case. Replacing the lines, hoses, and seals goes a long way to reliability.

 

[clinto]

I think VPed is correct.

I'll be honest-I see all these people here and on the various Facebook pages talking about ways to beef up the brake system, in terms of safety or redundancy.

And honestly, the absolute best thing you can do is just maintain the system. If you have a deuce that's more than about 25-30 years old, just go ahead and do everything: the master, the airpack, the wheel cylinders and most importantly, the steel brake lines and the rubber hoses.

I've had deuces now for............ 11 years and all my brake failures (3) have been the 30+ year old steel brake lines. 2 of them were the front to rear line and one was the line going to the front axle. One happened at 40mph and was quite entertaining. And by entertaining, I mean terrifying to the point of shaky knees afterwards.

You can buy NOS hoses on eBay for $110 shipped, from Memphis Equipment. They're old but they've been stored indoors and are probably decent (I've used them several times without incident). You can have a local hydraulic shop make DOT approved rubber or braided stainless hoses (Peashooter has all the info).

The hardest part is the lines. You can find a few of them on eBay, searching with the NSN. And they're steel, so it doesn't matter how old they are (assuming they've been stored indoors). But in the end, you're going to end up buying a bunch of hard line and bending and flaring it yourself. That's time consuming and it's not glamorous. No one wants to spend money on basic maintenance stuff, they want their $$$ to go towards upgrades and showy stuff. I get it, I'm mostly human as well.

I have an extra factory 1987-1989 dual circuit master cylinder mount and I'm trying to reproduce it, but I pretty much accept I'm not going to be able to do it. The cost to bring a reproduction to the market would be so high I doubt I'd sell a single one. I'm still talking to various companies (low volume sand casters, welding/machine shops, etc.) and trying to find a way to repro them at a cost that will make it a doable conversion, but I don't have a lot of hope. And the rest of the dual circuit system is a lot of work to reproduce and a lot of money. The masters are more expensive than the single pot, you need another airpack, bend a bunch of brake lines, you need to somehow break the air system up into 2 chambers, etc.

I've put a lot of thought into this and at the end, I believe the best advice for a safety minded operator is to buy a truck and just spend the thousand bucks rebuilding the entire system. New master, airpack, lines, hoses, wheel cylinders, etc.

If you don't want to do that, then copy what M35-tom did to one of his trucks: http://www.waterloospecialties.com/trucks/index.html

 

[98G]

It isn't the frequency of catastrophic failure that's the primary problem. It's the severity of potential consequences when it does happen.

Properly maintaining and preemptively replacing components only addresses the frequency of failure, pushing it that much closer to zero.

A redundant system addresses the other side of it - reducing consequences when a failure does occur - losing half your brakes instead of all of them.

Everyone who has a deuce has given it some thought, including some pretty good minds. No good answer has been forthcoming. The answers come down to "make it that much less likely" or "spend more than the truck cost to reduce consequences"

Back to the topic at hand - the hydraulic fuses would certainly cause uneven braking and a jerk to one side, but any braking is better than none... if the capacity of the hydraulic system is the stopper, perhaps an aux tank with more fluid would make it viable. But my knee-jerk reaction says this has already been examined by people more knowledgeable than me and there's more to it....

 

[tarnx]

This was intended to get other's ideas about it. I appreciate the interest. Yes I think that perhaps the system would have insufficient fluid once activated. Even with extra fluid available you would probably have to pump the petal to get more in the system. You are right an aircraft system would have a hydraulic pump supplying the pressure with a fluid reservoir. In the truck you are actually the pump with mostly only one pump available.

With a single point system I take it all the brakes work off the same input line. As you say apparently all the brakes on one side are together and so on the other side. I would put a fuse on each axle. That would only shut off the leak on a specific axle not a specific side. This idea would require a bit of reengineering and some one with experience with hydraulic circuits. The trucks don't seem to have a big history of brake failure so the system is quite reliable. Proper maintenance is probably all that is needed. It sounds like a winner over more expensive directions.

 

[98G]

They have an extensive history of brake failure. It's just not usually catastrophic.

I've got three trucks currently with single circuit brakes. Two of the three have brake problems making them unsafe to drive. (One has a confirmed bad air pack and has a new one on the way.)

 

[doghead]

What if the rear line going along the frame ruptures? Mine did recently, where it is not visible.

How will you know where to install such a device? If you put one on the front supply and one on the rear supply, seems the most practical. Does such a device exist? Where can it be purchased?

If you see any rust externlly, replace your lines. If your rubber lines look suspect, replace them(all at once).

Rebuild all of your wheel cylinders,

Rebuild your air pack.

Rebuild your master cylinder.

You should be ok for many years. Visual inspection is always needed and proactive repair/replacement is too.

 

[tarnx]

I suppose the definition of catastrophic depends on if you run into the back of another Deuce in convoy or a Honda. I agree PMs and rebuilds are probably the best direction.

doghead I don't wish to lead you astray. I would have to study the plumbing of the brake system and then figure out which unit to use and how and where to install it. I don't understand the stock system and I have no truck to look at. I wouldn't mess with it at this time. If your works as advertised keep it simple.

I was once asked how to keep the drug dogs from alerting on rooms in the dormitory. My response was don't smoke dope. Well that didn't work and they kept pressing me. Well I told them that as a reward the Security Police play with their drug dog with a tennis ball when they do well. Just toss one out when they make a sweep. Maybe the dog will go for it. I was at work when they did a sweep. Apparently that didn't work as thirty six tennis balls while it did mess up the dog it didn't the handler. Four more teams came in and finished the sweep. The moral of the story is be careful of what you tell people. One tennis ball might be construed as accidental but not thirty six.

 

[98G]

Catastrophic is defined as "mashed the brake pedal to the floor and nothing happened"

These single circuit brake systems are capable of doing that without warning. Full airbrakes with springbrakes are much to be preferred. (Which kind of begs the question of why I have 3 single circuit air over hydraulic trucks...)

 

[rustystud]

Having been in a truck with "catastrophic" brake failure I can honestly say "Never again !!! " . That is why I am so adamant about replacing "all" your brake lines with either "stainless steel" or "cunifer" lines. My CUCV has stainless steel lines and my deuce has cunifer lines. All my "rubber" lines have been replaced with PTFE stainless steel braided hoses in both trucks. I also only use DOT5 brake fluid in all my vehicles (except the Subaru as it has anti-lock brakes) . Yes the single circuit brake system has it flaws, but it can be mitigated with a few simple things. Yes it is time consuming as Clinto has said. Yes it will also cost you some money, but in the end you have a much safer vehicle and "peace" of mind. The rest as most have said is simple maintenance. The military had a simple PM program which we all should follow. After a predetermined amount of time and hours used, the vehicle needs certain things checked. Very simple really. The problem is most don't do it. As a mechanic in the seventh largest transit agency in America I can truthfully say "maintenance" was the number one priority. I was even the Inspector for a few years so I know that "brakes" was the number one single most important item inspected on "every vehicle" . We should have the same attitude. If we did, you would "never" hear of any vehicle loosing it's brakes again.
Now I know some are going to say "well you where a mechanic so it comes naturally to you" . The truthful answer is "no it doesn't" . I'm as lazy as the next guy, and if I'm not getting paid to check the truck why bother ? What I have done is develop a "habit" of checking my truck just like I developed a "habit" of checking the door locks at night on the house. At first you must "will' yourself to do it. Eventually you do it out of "habit" . That's where I'm at now. It just doesn't "feel" right if I don't check the truck. Anyone can develop this "habit" . As an added incentive to check your truck, just visualize yourself driving down the road and the brakes go out. Now visualize your wife or child or grandchild sitting next to you. Enough said.

 

[doghead]

I buy cunifer or cupro-nickle brake line.


http://catalog.fmsiinc.com/viewitems/brake-lines/cupro-nickel-brake-lines

https://cunifer.com/

 

[rustystud]

This is where I bought my lines from http://www.fedhillusa.com/ .

 

[doghead]

I buy mine locally at both NAPA and Advance Auto.

 

[VPed]

For those seeking to dispense with the single point of failure, I suggest adding a pinion brake with its own master cylinder and either a foot pedal or hand lever. This is relatively inexpensive. It does detract from original appearance but would not be too noticeable if installed between the rear axles.

 

[The King Machine]

That's a great idea with the pinion brakes. These axles are very popular with the off road crowd, plenty of kits available.

I've mulled this over plenty of times. I've replaced all my brake components with new parts but I still have that redundancy issue. I use my truck, its not parade machine so it bothers me when I'm out in the mountains.

Retrofitting the truck with an A3 system was considered, same with piecing together the dual circuit system off of the air force trucks.

At one point I thought one of these on every axle could be considered http://www.jegs.com/i/JEGS-Performance-Products/555/63000/10002/-1
The only problem is there would be no way to tell which line blew on the fly.

 

[98G]

Correct any misconception's I have -

My understanding is that due to the 6:1 difference in rotational speed, pinion brakes are really only useful at low speed.

Use at higher speeds result in rapid melting of components without much slowing of the vehicle.

Obviously i have no hands on experience with them.

 

[doghead]

You are correct.

 

[rustystud]

Correct any misconception's I have -

My understanding is that due to the 6:1 difference in rotational speed, pinion brakes are really only useful at low speed.

Use at higher speeds result in rapid melting of components without much slowing of the vehicle.

Obviously i have no hands on experience with them.

Yes they only should be used at slow speeds. Also pinion brakes add tremendous strain to the differential pinion bearings. The transit agency I worked at had at one time used "Telma" pinion brakes on the forty foot buses. They worked OK, but the differentials would go out ten times faster then normal. I'm not exaggerating either. The differentials were not designed for that kind of load. In my opinion a pinion brake should only be used as a "last" resort if all else fails.