Adding hydroboost brakes??

[daytonatrbo]

I specified the use of the pinion brake as an emergency brake. I know is spins much faster. That is also why it is very effective for braking. Monster trucks using military axles use pinion brakes and they get them to glow bright red from the heat. But they darned sure stop. And this would be using a disk brake and pads which are much more tolerant and forgiving of the heat.

Only very expensive carbon/carbon brakes maintain effective stopping when heated until glowing.

My point is, even in a 1-off emergency, you would smoke a typical brake rotor/caliper setup using it to try to haul a deuce to a stop via the pinion flange.

 

[rustystud]

"Typical" air brakes, as found on semis and even 5 ton MV, have a much better failsafe than ours. In that they fail on.

Actually our brakes will still function unless the lines themselves are compromised. The only reason semi-trucks will stop is because of the massive springs in the "Maxi-Cans". Even then if you loss all air at speed they won't be stopping you very fast since only the rear axles are applying the brakes and not to the same pressure as the air would provide. In fact in one of the tests I have to perform on brakes is to see what it takes to "override" the spring brakes. The engine will over power them at a stop, so you can only imagine what will happen at hiway speeds !

As far as the cost of converting to all discs goes, why don't you ask "HanksDeuce" what he spent on his brakes. It costs a very pretty penny ! The easiest and most cost effective way to upgrade your brakes is to go with the Dual Brake modification the military did. I also have upgraded my brake lines to the "cuprinol" (I believe that's how you spell it) lines and the stainless steel PTFE flexible lines that Peashooter was selling. Go to Peashooters posts on brakes.
Now my brakes are the same as any regular truck on the road today (minus the front discs) .

 

[rustystud]

Only very expensive carbon/carbon brakes maintain effective stopping when heated until glowing.

My point is, even in a 1-off emergency, you would smoke a typical brake rotor/caliper setup using it to try to haul a deuce to a stop via the pinion flange.

Ceramics. They've been around a long time now.

 

[quickfarms]

Disc brakes are only now being used on 18 wheelers.

I do not understand this fascination with disc brakes.

Drum brakes do work great when they are properly adjusted and in good condition.

I do like s cam brakes over wedge brakes.

 

[rustystud]

Disc brakes are only now being used on 18 wheelers.

I do not understand this fascination with disc brakes.

Drum brakes do work great when they are properly adjusted and in good condition.

I do like s cam brakes over wedge brakes.

Actually air-disc brakes on semi-trucks came out in the late 1970's. I worked on them. They did not perform well though and all manufactures went away from them until this present time. Our Breda bus (1990) had front disc brakes but they where a air over hydraulic thing and again where a beast to keep working right. Now they actually have real air-brake caliper brakes that work. They have many advantages in the commercial industry due to there easy maintenance and speed of service ( fast brake jobs ) . As far as being "superior" to drum brakes in service, they do perform a bit better but not in a huge way. They do cool down faster ( don't drive so fast ! ) and stop better when wet (stay out of the river ! ) but in overall stopping distances not so much. That is more a combination of tires ( tread contact), vehicle weight, and braking bias ( example: 60 percent front-40 percent rear ) . In fact at work we have over 20 different buss ( Gillig-New Flyer-Neo-Plan etc. 1,400 in total ) and all have drum brakes except a few Breda busses left. And before anyone says "buses don't go fast" our buses must go on the high-ways and maintain 60mph just like every other vehicle out there and be able to stop. The best performer is usually the 3 axle 60ft New Flyer. This over the 40ft Gilligs. We must test each buses brakes after every brake rebuild and every 12,000 miles (Federal Law) . We have this fancy computer that tells you the "Brake Force" and total distance traveled and on and on and on ! All this to say that drum brakes still are great brakes and will safely stop you. Now like I said earlier, if I had the money to spend I would go with disc brakes just because it would be cool ! and easier to work on.

 

[IsaLandr]

Disc brakes are only now being used on 18 wheelers.

I do not understand this fascination with disc brakes.

Drum brakes do work great when they are properly adjusted and in good condition.

I do like s cam brakes over wedge brakes.

I'm going to chime in here a bit and point out that air disc brakes have been the dominant standard in most of Western Europe since the early 1990s, and there is a vast body of supporting evidence to support their superiority in every possible aspect. I remember wishing I had them on my truck back when I was still actively driving during that period.

They stop better, they are more reliable, they dissipate heat better, they are easier and safer to work on, less expensive to maintain... the list of advantages goes on and on. So far the only real disadvantage I've yet seen is that in some cases they have been accused of stopping too well, and there is documentation to support that opinion, as well.

It's only here in North America that they are not yet adopted industry-wide and are only very recently being adopted in even small production numbers. However, those numbers are increasing, and the eventual intention is a compleat transition to disc instead of drum.

Here's some reading material for you:

http://www.todaystrucking.com/whats-stopping-you-the-4-1-1-on-air-disc-brakes
http://www.truckinginfo.com/blog/on...ficent-stopping-power-of-air-disc-brakes.aspx
http://fleetowner.com/regulations/truck-stops-here-0201
http://auto.howstuffworks.com/auto-parts/brakes/brake-types/truck-brakes3.htm
http://www.vehicleservicepros.com/n...s-offer-performance-advantages-to-drum-brakes
http://www.landlinemag.com/Magazine/2013/Feb/Section2/disc-v-drums.aspx
http://www.alu.army.mil/alog/issues/SepOct06/disk_brakes.html

And there is a lot more where that came from. A simple google search will provide more than you could ever want to read.

I too prefer the S-cam to wedge brakes, but wedge is what we have on our M939s, and a conversion away from those is not a simple procedure. Nor an inexpensive one. As much as I'd rather have S-cam than Wedge, however, I'd move to discs in a heartbeat if it was economically feasible.

 

[daytonatrbo]

As far as the cost of converting to all discs goes, why don't you ask "HanksDeuce" what he spent on his brakes. It costs a very pretty penny ! The easiest and most cost effective way to upgrade your brakes is to go with the Dual Brake modification the military did. I also have upgraded my brake lines to the "cuprinol" (I believe that's how you spell it) lines and the stainless steel PTFE flexible lines that Peashooter was selling. Go to Peashooters posts on brakes.
Now my brakes are the same as any regular truck on the road today (minus the front discs) .

I'm actively looking into that route. Unfortunately peashooter doesn't offer his kits currently, but I've contacted him to see what knowledge he can share as far as the soft lines, in addition to the excellent info he has already shared about the hard lines.

 

[sandcobra164]

Rustystud,
I'll have to disagree with you slightly on "Maxican" parking brakes. A few years ago on the way to Ft. Stewart, a Soldier somehow thought it would be a good idea to set the parking brake on an M1078 LMTV going 55 mph. down the road. It immediately locked the rear axle and nearly caused the truck to flip over as it skidded out of control and smashed into a guardrail. It was towing a water buffalo that was empty and flipped over during the ordeal. That was a fun recovery. I winched to the water bull to get the truck out of the traffic lane it was blocking off to the side of the road, used the crane to upright the water buffalo and was able to drive it back to the armory which was only 4 miles down the road. One example I could think of as not working too well would be a gradual loss of air pressure on an M939 series truck. Sure, the brakes will start to apply once the pressure gets down to around 60 psi but not with much force as there would still be air counteracting the spring. The parking brake doesn't magically pop out and release all air going to the parking brake like the new trucks when there is a drop in pressure.

 

[SP5]

What seems to be one of the biggest hassles with a Hydroboost/Hydromax system for a deuce is the problems of mounting the master cylinder and a power steering pump.
You don't "have" to have discs, a Hydromax master, of the right size in piston bore, (I think it's two inches,)operating off of a power steering pump can easily supply the required pressure and volume of fluid to the stock drum brakes, and gives you a safe duel curcuit system.
In the under 26,000 gvw catagory, (like a deuce), all the truck companys are offering Hydromax disc systems, mainly as a way of getting around the "air brake indorsement" requirements of many states.
It does'nt take much reading in the 5ton forums, or the FMTV forums to realize the constant problems with anything and everything even remotly connected with air brakes.
The main ability of air is the ease with which trailers may be connected-up, or being able to use the vehicles own brakes if it is being towed.
For any kind of a single vehicle situation hydraulic is so much more simple,, and what's wrong with electric, or electro-hydraulic for a trailer.
I'am starting to think that all this stuff with compressors/tanks/driers/check valves/reversing valves/this valve/that valve/ and more valves, all connected with miles of piping, is something that it would be nice to say "good riddence" of.

 

[rustystud]

Rustystud,
I'll have to disagree with you slightly on "Maxican" parking brakes. A few years ago on the way to Ft. Stewart, a Soldier somehow thought it would be a good idea to set the parking brake on an M1078 LMTV going 55 mph. down the road. It immediately locked the rear axle and nearly caused the truck to flip over as it skidded out of control and smashed into a guardrail. It was towing a water buffalo that was empty and flipped over during the ordeal. That was a fun recovery. I winched to the water bull to get the truck out of the traffic lane it was blocking off to the side of the road, used the crane to upright the water buffalo and was able to drive it back to the armory which was only 4 miles down the road. One example I could think of as not working too well would be a gradual loss of air pressure on an M939 series truck. Sure, the brakes will start to apply once the pressure gets down to around 60 psi but not with much force as there would still be air counteracting the spring. The parking brake doesn't magically pop out and release all air going to the parking brake like the new trucks when there is a drop in pressure.

Sure the MaxiCans can lock-up an axle in different types of conditions. Especially if the road is wet. The reality is that MaxiCans can be overridden by the engine. Just like I stated in my last post, there is a "Federal Government" test for checking MaxiCans. Any good running engine "will" overpower the brakes. As far as the emergency brakes coming on like you described (unless the "LMTV's" have no safety standards) that shouldn't happen. All modern trucks and busses have built in safety measures to "prevent" such accidents as you described. I believe if the truth came out there was another factor involved in this accident. Plus it was towing a trailer.
As far as how fast the maxicans come on, once the air-pressure hits 40psi they come on immediately ! this is again a Federal Safety Standard. The air-pressure alarm comes on at 60psi.
I also don't like the "Wedge" style brakes. It has been proven that the "S" cam brake provides more braking force on the brake shoes then the Wedge style does. I can only imagine the military went to this design because of safety. The wedge air-cans are behind the wheels and not exposed to any flying shrapnel, while the S cam air-cans are on the side and can be damaged by a side explosion or shrapnel. That is the ONLY reason I see the militery going with this old design.

 

[rustystud]

I'm going to chime in here a bit and point out that air disc brakes have been the dominant standard in most of Western Europe since the early 1990s, and there is a vast body of supporting evidence to support their superiority in every possible aspect. I remember wishing I had them on my truck back when I was still actively driving during that period.

They stop better, they are more reliable, they dissipate heat better, they are easier and safer to work on, less expensive to maintain... the list of advantages goes on and on. So far the only real disadvantage I've yet seen is that in some cases they have been accused of stopping too well, and there is documentation to support that opinion, as well.

It's only here in North America that they are not yet adopted industry-wide and are only very recently being adopted in even small production numbers. However, those numbers are increasing, and the eventual intention is a compleat transition to disc instead of drum.

Here's some reading material for you:

http://www.todaystrucking.com/whats-stopping-you-the-4-1-1-on-air-disc-brakes
http://www.truckinginfo.com/blog/on...ficent-stopping-power-of-air-disc-brakes.aspx
http://fleetowner.com/regulations/truck-stops-here-0201
http://auto.howstuffworks.com/auto-parts/brakes/brake-types/truck-brakes3.htm
http://www.vehicleservicepros.com/n...s-offer-performance-advantages-to-drum-brakes
http://www.landlinemag.com/Magazine/2013/Feb/Section2/disc-v-drums.aspx
http://www.alu.army.mil/alog/issues/SepOct06/disk_brakes.html

And there is a lot more where that came from. A simple google search will provide more than you could ever want to read.

I too prefer the S-cam to wedge brakes, but wedge is what we have on our M939s, and a conversion away from those is not a simple procedure. Nor an inexpensive one. As much as I'd rather have S-cam than Wedge, however, I'd move to discs in a heartbeat if it was economically feasible.

There is a lot of material stating how great disc brakes are. Most of it is from manufactures wanting to sell there product. Sure Europeans have used disc brakes since the 1990s and most all where air over hydraulic or just plain hydraulic systems. Also Europeans have had stricter emission and mileage laws then here. I will explain more later. It wasn't until recently that the manufacturers finally figured out all the problems of a true air-disc system. I know as I talked with the factory rep for Bendix 2 years ago on this very subject. Again don't get me wrong here. Disc brakes are great ! Are they the answer to all the worlds problems ? NO. They have draw-backs just like everything else. Cost is number one right now. Disc rotors cost almost 4 times the amount of a drum. Disc pads cannot be rebuilt in shop facilities unlike shoe brakes which are quite easy to replace. Disc calipers are FAR more complicated then wheel cylinders and over 10 times the cost of a wheel cylinder. The new air-discs cost almost $1000.00 each !!!! and cannot be rebuilt except at the factory.
So do the disc brakes provide 4 to 10 times the stopping ability of drum brakes ? NO. Disc brakes on average can provide up to 25% more braking ability over drums. Is the cost worth it ? Up until now most manufacturers said no, but things are changing. The major reason automotive manufacturers went to disc brakes was because of the weight savings. The biggest factor in automotive technological advancement has been the Federal standards for fuel economy and emissions.
Lighter vehicles means more fuel economy. If it wasn't for the Feds we all would be driving our monster 500cid 22ft long land yachts and loving it ! Over the years I have owned 3 big Cadillac's and one did have the 500cid engine. I really loved that car ! The other 2 had the 472cid engines. Now I have a Subaru with a 2.2 liter 4 cylinder.
Up until a few years ago Semi-trucks and busses where exempt from this governmental intrusion. Now everyone must meet emission and fuel mileage standards. I should post a picture of the exhaust system of one of our new busses. It is crazy !
So with governmental standards pushing the trucking industry they must lighten there trucks, and disc brakes will help do this. Does this mean that disc brakes are the best thing since sliced bread ? Again the answer is no. So when you compare the use of disc brakes by others you need to understand what really is going on.

 

[rustystud]

This is the modern exhaust system on a bus. It is computer controlled and interfaces with the engine ECM.

 

[sandcobra164]

The truck in the incident I described was pulling a trailer but common practice with the M105's and M149's is to leave the trailer air hoses disconnected and let the prime mover handle braking chores. That was how it was done for this particular incident as well. I've always wanted to test the parking brake in a similar manner although at a much slower speed just to see what would happen on an LMTV or HEMMT. I got my answer that day. For what it's worth, it was a dry clear day traveling down a 4 lane expressway with a grass median . The guardrails prevented the truck from crashing into the adjacent bridge supports it was attempting to travel under. My conclusion for what happened were based upon statements taken from both the driver and passenger. The driver pulled up on the parking brake knob and the truck started skidding due to the rear tires being locked up. Skid marks left on the pavement concurred with the statement. They were probably 400 feet long.

 

[rustystud]

The truck in the incident I described was pulling a trailer but common practice with the M105's and M149's is to leave the trailer air hoses disconnected and let the prime mover handle braking chores. That was how it was done for this particular incident as well. I've always wanted to test the parking brake in a similar manner although at a much slower speed just to see what would happen on an LMTV or HEMMT. I got my answer that day. For what it's worth, it was a dry clear day traveling down a 4 lane expressway with a grass median . The guardrails prevented the truck from crashing into the adjacent bridge supports it was attempting to travel under. My conclusion for what happened were based upon statements taken from both the driver and passenger. The driver pulled up on the parking brake knob and the truck started skidding due to the rear tires being locked up. Skid marks left on the pavement concurred with the statement. They were probably 400 feet long.

Those where some strong MaxiCan springs then ! I bet the LMTV was hauling light or empty. No weight on the axles. Like I said before they can lock up the brakes in special circumstances, but they really are not suppose to lock-up the axles. Do you honestly think the manufacturer designed them this way ? How many accidents would there be on the high-ways if this happened whenever a truck lost it's air-supply ? No, they are to help slow you down and then help keep you there. And before anyone says "semi-trucks never loose their air" let me tell you this happens a lot. That is why ALL air tanks now have one-way check valves, so if a line is ruptured or torn out there still well be some air in the system to help get you safely off the road. I remember a time in the 1970's when air-compressor lines where breaking and trucks where loosing all the air. All trucks had copper lines to handle the heat just like our deuces do. The copper lines where "work hardening" and then breaking due to the vibrations of the engines. It was about this time that manufacturers started to use flexible hoses on the air-compressor to wet tank lines. That is why you almost always see the stainless steel PTFE hoses on there today. They can handle the heat and are very flexible, but before the PTFE hoses came out they tried other types of rubber hoses and they had a high failure rate. Needles to say there where a lot of trucks relying on the MaxiCans to help stop them !
I still think of the late 60's to mid 70's as a "Wild West" time for the trucking industry. There was a lot of crazy crap going on back then. That is why there are so many laws now governing the trucking industry.