modern dual circuit air over hydraulic brakes

[rustystud]

According to federal regulations they do need to be replaced at least once a year, sooner if you have high mileage. I was a safety inspector and can post the regulations when I get home.

 

[rustystud]

We are talking about the diaphragms, not the whole can here.

 

[Mullaney]

According to federal regulations they do need to be replaced at least once a year, sooner if you have high mileage. I was a safety inspector and can post the regulations when I get home.

.
Curiosity Question @rustystud :

Is that annual replacement for the rubber diaphragms in air brake chambers a requirement for passenger hauling vehicles?

 

[patracy]

Do you know of a 9/16-18 tube nut that accommodates a 5/16" OD tube bubble flare? All I'm seeing is 3/16" tube when searching.

Dunno. I have 1/4 hardline here. I replaced the rear hardline with 1/4 on mine this week. Was planning to just run 1/4.

 

[rustystud]

.
Curiosity Question @rustystud :

Is that annual replacement for the rubber diaphragms in air brake chambers a requirement for passenger hauling vehicles?

Yes, passenger and over the road Semi-trucks, and dump trucks. Basically any big rig that can cause severe harm to the general public if they have a brake failure.
Considering the sometimes lack of quality control these diaphragms can have, it's a wonder they don't require them replaced every month. I don't even know if any diaphragms are even made in the USA anymore. I've seen them fail after just a week in service. Then again I've seen them last well over two years with no problems. This particular vehicle got missed in it's yearly replacement and somehow got put back into the yearly rotation. My own personnal truck had them in for over 5 years before I replaced them. They did have dry rot though.

 

[patracy]

Forgot to post this yesterday, but my hydromax booster came in. Happened to have a plate that matched two of the mounting holes and had a large opening for the pushrod. Just had to drill two holes and now I have a reinforcement plate to install it. The feed side of hydraulics uses a odd fitting, sweeting performance has a AN adapter for it that I ordered. So I'll be able to use all AN hoses.

My thought is to mount it to the firewall where the large heater vent would have gone through. I'll use pillow bearings and a rod mounted just above the column to allow me to hang the pedal and work this brake.

Sent from my SM-G965U using Tapatalk

 

[rustystud]

Forgot to post this yesterday, but my hydromax booster came in. Happened to have a plate that matched two of the mounting holes and had a large opening for the pushrod. Just had to drill two holes and now I have a reinforcement plate to install it. The feed side of hydraulics uses a odd fitting, sweeting performance has a AN adapter for it that I ordered. So I'll be able to use all AN hoses.

My thought is to mount it to the firewall where the large heater vent would have gone through. I'll use pillow bearings and a rod mounted just above the column to allow me to hang the pedal and work this brake.

Sent from my SM-G965U using Tapatalk

Now that looks real nice !

 

[Mullaney]

.
So... I keep looking and I haven't found any hard evidence of required annual replacement of air brake diaphragms.

For many years, I worked on a small fleet of trucks that dragged trailers. Those trailers hauled military vehicles used to build steel high lines. Basically we built electric power generation infrastructure. From Florida to Virginia, and west to the far reaches of Kentucky. We had some older trailers that were "pre spring brake" pieces of equipment. Reading trade publications, it seemed like a good idea to upgrade those trailers AND it also locked the trailer in place when trying to back under them.

In all that time, I only remember replacing those "pancakes" when there was an air leak. I know we had ICC numbers on the tractors. Think those became MC numbers somewhere along the way. I know the drivers had to carry a log book and I did too when somebody was on vacation and I ran the roads... What I am trying to say is that we were a trucking company that had to conform to the rules...

Am I missing something?

In my search, I also came across the Bendix Air Brake Handbook BW5057 US_004.
Lots of good information about air braking systems, air dryers, brake chambers, and assorted valving.

 

[Floridianson]

.
So... I keep looking and I haven't found any hard evidence of required annual replacement of air brake diaphragms.

For many years, I worked on a small fleet of trucks that dragged trailers. Those trailers hauled military vehicles used to build steel high lines. Basically we built electric power generation infrastructure. From Florida to Virginia, and west to the far reaches of Kentucky. We had some older trailers that were "pre spring brake" pieces of equipment. Reading trade publications, it seemed like a good idea to upgrade those trailers AND it also locked the trailer in place when trying to back under them.

In all that time, I only remember replacing those "pancakes" when there was an air leak. I know we had ICC numbers on the tractors. Think those became MC numbers somewhere along the way. I know the drivers had to carry a log book and I did too when somebody was on vacation and I ran the roads... What I am trying to say is that we were a trucking company that had to conform to the rules...

Am I missing something?

In my search, I also came across the Bendix Air Brake Handbook BW5057 US_004.
Lots of good information about air braking systems, air dryers, brake chambers, and assorted valving.

Yea I still operate a class 8 and would like to know. Been looking through the Federal Regulations till my eyes hurt and nothing on replacing the diaphragm once a year. Best thing you can do for a Deuce is check / clean you compressor air filter and install an air dryer. Water and oil will take it's toll on parts.

 

[rustystud]

Since I still have my "Class A" CDL , which means I can drive any over the road vehicle except certain vehicles that carry Nuclear waste products, I need to know the Federal Laws. Since the Class A,B,C style license was introduced years ago every state in the union has gone to it and every other type of heavy truck license became invalid.
Here is something everyone should read who still drives a truck with air-brakes.
Also according to Bendix, they say to replace the "whole" brake can (not just the diaphragms) every 2 to 5 years depending on the model of brake can.

 

[patracy]

I started reading that, but it's a rather lengthy document. Is there a part in there that states from the government that the brake diaphragms and/or cans have to be replaced every year?

 

[gringeltaube]

Is there a part in there that states from the government that the brake diaphragms and/or cans have to be replaced every year?

Apparently not. I've read (twice) all 30 pages looking for just that. Might have overlooked it, though...

 

[Floridianson]

Hope I do not get into more trouble. Yea when I sanded plowed and salted the roads in Va. that might take it's toll on the cans or damage from stones or backing up then we need to worry. Same as OTR trucks running where there might be salt on the road or damage from road like hitting something on the road or backing up. Bendix is there recommendation to change out the cans every 5 years not Federal from what I see. Nothing about replacing the diaphragm every year from the Feds. My cans are 30 years old on my 915A2 and still looking good and no damage plus they are painted. Me replace diaphragm when it blows out and keep trucking.

 

[rustystud]

I started reading that, but it's a rather lengthy document. Is there a part in there that states from the government that the brake diaphragms and/or cans have to be replaced every year?

The federal mandate for yearly replacement is for transit and government vehicles only, though if you read the document carefully you will see that no air-can can pass the federal standard for years. The slightest leak or lack of pressure is cause for replacement and or side-lining of your vehicle on a highway. That is another reason Bendix says two years max for most brake cans. Some Maxi-cans can go up to five years though. Anyone running brake cans that are 30 years old has never had a "safety inspection" from the State Patrol. There is no way in "Hades" that they would pass any safety inspection. If you were to open one up you would find rust and gunk everywhere, plus I would guarantee that the diaphragms would break apart. Running them and telling others you are running them like that is not wise from a legal point of view.

 

[Floridianson]

Thanks I will look over the form again. As for being inspected I would get pulled over maybe once a month in Va. checked for over weight and safety inspection. Hauled tonnage from the quarry in 1981 for 5 years. Never failed safety inspection but plenty of over weight. This thread is getting way off topic. I will pull apart a can from the 915 and lets look and see but I will start a thread so this one does not get so far off topic.

 

[Superthermal]

Forgot to post this yesterday, but my hydromax booster came in. Happened to have a plate that matched two of the mounting holes and had a large opening for the pushrod. Just had to drill two holes and now I have a reinforcement plate to install it. The feed side of hydraulics uses a odd fitting, sweeting performance has a AN adapter for it that I ordered. So I'll be able to use all AN hoses.

My thought is to mount it to the firewall where the large heater vent would have gone through. I'll use pillow bearings and a rod mounted just above the column to allow me to hang the pedal and work this brake.

Sent from my SM-G965U using Tapatalk

Getting this great thread back on topic... Check
patracy Can you get the part numbers for these parts MC and Hydro boost unit posted up? If I missed it back in the thread I apologize. Reviewing the brakes on my M813, I have a preference for the air over hydraulic but I do feel a dual circuit brakes is a mandatory safety item. The Hydro with the redundancy on hydraulic feed from the PS pump and the internal electric pump as a back up with the added dual circuit MC I feel this is the system for my M813.
The Deuce and the M809 have some parts in common and I was wondering without a lot of cross checking if the parts you are using could be used for a M809 with all three axles in place.
I had not planned to keep the trailer air brake connection in place so I don't think keeping the air pack is a priority for me. Though a M1092 trailer if dropped off at my home for free would change my thoughts on that!

 

[patracy]

The MC part number I ordered is MC39577 (It was on page 2 of this thread). I don't have a part number for the hydromax, as it was a used unit off ebay from a International truck. The only downside to that unit is that it's a 12v unit. I plan to just plug it between the batteries though. As it's a "emergency" pump and not something that should be used all the time. There are 24v pumps out there for these. But they're not cheap. I likely would have more in that pump than all the parts I've collected so far.

I haven't done anything else with my truck yet. Work has been too busy and @Spot_ll has been busy too. Maybe in the next day or two we'll get the glass back into it. Then I need to start working on things like mounting the power steering ram, PS pump resv., PS cooler, and work on things like the brake upgrades and repacking all the hubs/adjusting brakes, exc. Since the brake upgrade needs the power steering pump, I'll be doing both projects at the same time. I probably will not bother with the trailer brake setup until all that stuff is done and it's a add on at that point.

 

[SteelNinja]

what about just leaving the system alone and converting to disc?

 

[Superthermal]

what about just leaving the system alone and converting to disc?

That is a great question!
Safety. The primary reason is safety backup. With the Stock system any failure in any of the following ends in catastrophic failure: MC seal failure, Air pack issues, hard-line pipe corrosion, soft-line flexible hose deterioration or physical failure, and wheel cylinder failure. Not to mention there are several check valves.

By adding dual circuit brakes you are providing redundancy in the key areas by basically splitting the brake system into two parts rather than one. The single output master cylinder is replaced with a dual piston unit that has two pistons one in front of the other, where one drives the front brakes and the other the rear. This one modification is key for safety.

Also being covered in the thread is adding a hydro max or hydro boost that removes the air system from the brakes that is a corrosion point in most rigs and places the boosting of the system to a hydraulic loop run by an added power steering pump or other hydraulic system pump. The hydro max systems go a step further and adds an electric driven pump as a backup to this hydraulic system, giving the boost of the system a safety in redundancy as well.
All in all, safe is key.

Disc brakes are great, but they would only replace the wheel cylinders in the system and not the other 80% of the failure points.
Having had a single circuit system in my 1966 FJ40 and having had it fail on "The Lions Back" in Moab Utah I will have dual circuit brakes just because of that one day. Your welcome to look it up and tell me you wouldn't be scared not having brakes on that sandstone fin. :O

Thank GOD that an Angel spoke to me in a clear calm voice and told me as I was nearing the half way up point..." BACK DOWN". When I took and put the trans in reverse, I pushed on the brake peddle to slow my decent and the brake peddle went straight to the floor with ZERO pressure. My transfercase rear mounted park brake only worked... "kinda" going forwards. My tranfercase and trans were worn from V8 power and under tension in reverse would pop out of gear after clicking a few times. It popped out about 30 feet from the bottom. Quick driving skills kept me and my friend safe. If I wouln't have listened I can only imagine what would have happend when I went to make that 4 point turn around on the rounded top of the Lions Back.

I will not have single circuit brakes for long on my M813. Since that experience brakes are Safety #1 and I am sure in Utah my M813 will see some steep mountain sides.
Be safe out there.

 

[patracy]

what about just leaving the system alone and converting to disc?

There are disc brakes out there for them. But I'm much more interested in having dual circuit for safety. The drum brakes are completely suitable to stop the truck. Now, upkeep, they probably would be easier to deal with. I think there's several threads about disc brake conversions. I wouldn't mind it, but that would be an expensive endeavor.