Split Brakes

[rflegal]

Similar concept - lots of raw material to start

 

[m-35tom]

well since i don't think anyone really knows this yet, find someone with a air force truck with dual brakes and have them get the casting number from the MC. it had to come from somewhere and if it has a number should be tracable.

 

[rflegal]

keep in mind that when the system is working correctly, the MC does NOT apply the brakes. it only controls the air pressure regulator on the airpack. it is the MC on the airpack that applies the brakes. with no air pressure and ONLY then, does the primary MC push on the piston of the airpack MC to apply the brakes.
tom

Absolutely - I agree Tom. As I think about it, the MC really contributes little as you say but acts as a reservior and a hydraulic actuator; the air piston does all the work.

But that still brings the question; in the dual system, the airpacks are the same as on the single, yes? If they applied the same stroke as on the single system, the same volume of fluid at the same pressure would be applied to fewer WCs. But, the pressure regulation part of the airpack prevents overpressuring, yes? I hadn't thought of it that way. Airpacks are pressure controlled via the compensator. The compenstor piston will move relative to hydraulic pressure and force the control valve closed, preventing overpressure? So two deuce MC idea should work just fine and give you truely independent systems. Is there a good schematic on airpack operation principles anywhere in the TMs?

I know some think dual MCs would be tough, but you'd know that the MC matched the airpack and the systems were truely independent.

 

[emmado22]

NSN 2530-01-257-7643 Dual Circut Master Cylinder

All 3 listed below are the exact same part.

Bendix part # 2232693
AM Generals part # 5934071
TACOM's part # 12357047

Another useful tidbit is the Bore Diameter is 2.742 inches min and 2.747 inches max

 

[rflegal]

Unfortunately Bendix made that part No 2232693 obsolete 07/2001
Dang

http://www.bendixvrc.com/itemDisplay.asp?documentID=3342

 

[m-35tom]

yes same air packs
the air packs would not move the same stroke, they would only move enough to apply the same pressure . in the control valve the pressure from primary MC is balanced against the air pressure on the other side of a piston, controlling the air pressure to the apply piston, and the air pressure to the service trailer connector. (making the piston in the controller larger reduces the pedal effort to apply brakes.)

tom

 

[rflegal]

Thank you sir, that's exactly what I thought, the stroke would be less... what a wonderful system.

 

[tiger422]

Tom
I am very intrested in the system you have more info please.
Jim

 

[jesusgatos]

...you have several options for dual brakes and the one i favor is just as simple as any other. that is to do away with the primary MC and replace it with an air threadle valve which then controls air to basic air units with a MC on each. this is the most modern system out there and used by isuzu and nissan on their box trucks. it also reduces the pedal pressure to less than that of any car.

I'd like to hear more about the components that would make up this type of system, and would be required for a Deuce conversion. Sounds interesting. Could you then use three air valves? You know, to get a completely separate brake system for each axle...

 

[m-35tom]

what we need is the casting #, not the part number.

i used the pedal and valve assy from a 900 series truck, mounted on a reinforced firewall. (along with the air assist hydraulic clutch)
air packs are from a nissan UD box truck, the rest is just plumbing.

 

[Chinookpilot77]

I'm just brainstorming here guys, try to be gentle if I'm totally off base, but why couldn't you use a medium duty truck MC along with its vacuum booster can and then get an electric vacuum pump. If the power is cut, for whatever reason, I assume the check valve on the booster would allow you one or two brake applications...if not, then I've stopped a deuce with no power assist, not easy, but it can be done for sure. I'm just wondering if that would be viable. I realize its not "authentic, but then neither is my bobbed truck.

 

[rflegal]

You could, would be a very interesting idea. I don't think you'd even need the vac pump on a gasser, not sure how much vac she'll pull. It would need to be matched. Or you could do a hydroboost from med/heavy duty truck, install an appropriate PS pump and combine it with a hydraulic power steering install like I did on my FJ40. There are quite a few options I think. Just comes down to what you're comfortable/experienced with and if you have the skills and fabricating know-how to do it safely. Its my understanding that, other than the dual system that the military used (which is not available as a retrofit publicly), nobody has a canned kit that's plug and play. You have to do all your own R&D and the easiest path is to copy the military. The harder one is something original like what you proposed. But hey that's the fun part, right? That's also why we're on the mod forum with this one too, right?

 

[rflegal]

How about a hydroboost for the brakes running from a complete aux. hydraulic system running off the PTO with quick connect ports on the bed side and back to run ancilliary equipment like the equipment underground; a hydraulic lift jack, or drill or chain saw! The chain saw is too cool... no engine noise from the saw itself, just don't cut the hoses.

 

[jesusgatos]

Can the hydraulic PTO be used while the vehicle is in motion? I just got one (came with a transfer-case I bought) and was wondering about that...

 

[Chinookpilot77]

I dont know about you guys, but I actually thought my idea for this was pretty straight forward. Two parts, re-plumb some brake lines, fab up a brake pedal, and done. Now these may not be the exact parts I'd use, but something similar enough would absolutely do the job.

Tuff Stuff 2124NB 9" dual diaphragm booster combo:eBay Motors (item 390114795903 end time Nov-12-09 02:57:08 PST)

ELECTRIC BRAKE BOOSTER VACUUM PUMP :eBay Motors (item 330370881621 end time Nov-22-09 11:24:27 PST)

 

[Chinookpilot77]

Anyone have any idea what the largest vehicle on the road to use vacuum boost is? I want vacuum, not hydro for ease of installation. A lot of diesel are hyro because diesels dont normal pull a decent vacuum. BUT, I am going to install a separate vacuum pump. all I need to do now is find out which booster/MC combo to use.

The best option would be to have a MC off a 4 wheel disc brake truck, but I'd try a drum.

 

[stumps]

Anyone have any idea what the largest vehicle on the road to use vacuum boost is?

It was common in the days of gasoline powered trucks and school buses. I have an F600 2 ton with a vacuum over hydraulic system... single circuit too!

Diesel pickup trucks generally have a belt driven vacuum pump to handle the ordinary vacuum assist power brakes.
-Chuck

 

[mudguppy]

i don't understand this statement:

... I want vacuum, not hydro for ease of installation. ... I am going to install a separate vacuum pump. ....

it is simply one extra hydraulic line. it goes from pump-booster-steering box vs pump-box. that's it. in either case, you're still doing the hard part (swapping the master cylinder). but w/ vacuum, you're installing a seperate component (stand alone pump) and you have to fit that gi-normous brake booster in there, too.

you'll have to go back many moons to find vacuum pumps on diesel (to drive a vacuum brake booster, that is). even in light duty trucks, they all made the switch to hydro-boost in mid-90's. ex: my '96 cummins has a gear driven vac pump in front of the power steering pump. in '97+ they went to hydroboost and eliminated the vac pump. same for ferds and cheby's. i think medium duty switched before that.

 

[Chinookpilot77]

I'd love to be able to use hydroboost, but I have no idea where I'll mount the pump itself, since the slot above my generator is already spoken for. any ideas?

 

[mudguppy]

... since the slot above my generator is already spoken for. any ideas?

is that where the 5 ton pump could be bolted on to?

i have the PSC hydro pump mounted below the IP. it's on a custom built bracket that Jim (Cavemantrucks) built. it runs off of a belt that reaches over to the alternator. i can take pics if you help remind me...