Dual Circuit Brake Engineering Thread

[rustystud]

I see that this bracket discussion is still ongoing. Don't have time - mood to go through the entire thread again but how many pieces we are talking about and estimate for max price?

My son does special blacksmithing orders for all kind of historic things, especially small order sizes. Below some pics of suspension brackets he made for a very accurate replica of the first electric trolleybus for the Czech Republic at the beginning of 1900. The pieces are about 32 cm high, weighing several kgs and very sturdy, as you can see.

View attachment 718261 View attachment 718258 View attachment 718259 View attachment 718260


I am not sure if he would be interested at all, but before asking I have to know a bit more details.

Those are some nice aluminum pieces, but can he make them out of steel ?

 

[Robo McDuff]

Those are some nice aluminum pieces, but can he make them out of steel ?

Not sure if he can make them out of aluminum, but you are looking at pure solid high quality steel. I think it these are actually built out of two pieces welded together since he did not have the power hammer needed to make it out of one piece (not sure). With the big steam hammer active, he can do more.

 

[rustystud]

Not sure if he can make them out of aluminum, but you are looking at pure solid high quality steel. I think it these are actually built out of two pieces welded together since he did not have the power hammer needed to make it out of one piece (not sure). With the big steam hammer active, he can do more.

Those are steel ? Then wow ! He did a great job on them !

 

[Robo McDuff]

His master work, the 50 ft by 20 ft double gate with side wings, symbolizing a lathe. Took 3 years to complete. Look at his website under "mondra gate"
(I should update that site, its over 10 years old mostly).

 

[jkcondrey]

Has anyone tried a new mockup with two, standard master cyclinders, side by side with a double plunger, connected by a through rod to the brake pedal. It would take some metal work underneath, but if you could adapt it that way, then add another aipack for the second master seems like it could work. With the single master parts much more readily available that seems easier to me. I don't have all the metal fab skills but seems like making some new linkages and decent bracket for the second master would be easier than the highly complicated design of the a3 bracket. Just trying to throw another realm of possibility.

 

[clinto]

View attachment 726454Has anyone tried a new mockup with two, standard master cyclinders, side by side with a double plunger, connected by a through rod to the brake pedal. It would take some metal work underneath, but if you could adapt it that way, then add another aipack for the second master seems like it could work. With the single master parts much more readily available that seems easier to me. I don't have all the metal fab skills but seems like making some new linkages and decent bracket for the second master would be easier than the highly complicated design of the a3 bracket. Just trying to throw another realm of possibility.

A. Lot of work to modify the existing master/pedal mount work this way
B. winch trucks now have no good way to shift PTO

 

[jkcondrey]

I don't think you would have to modify the existing mount, but add a beefy bracket to mount the second one up. Use some heim joints and a rod to connect the two to each other and the pedal. For non winch folks could be possible. I'd love to have duals, but the parts availability and the lack of rebuild kits seems to negate the a3 change over for a large crowd. Do you have an under carriage pic on the winch trucks I could use for comparison? I think I may buy another master just to tinker with and see if this could be an alternative.

 

[rustystud]

I don't think you would have to modify the existing mount, but add a beefy bracket to mount the second one up. Use some heim joints and a rod to connect the two to each other and the pedal. For non winch folks could be possible. I'd love to have duals, but the parts availability and the lack of rebuild kits seems to negate the a3 change over for a large crowd. Do you have an under carriage pic on the winch trucks I could use for comparison? I think I may buy another master just to tinker with and see if this could be an alternative.

I believe you would run into legal problems real fast. The DOT really frowns on modifying brakes from the "norm" . Going to a modern dual master cylinder is fine. After all that is modern technology now. Adding calipers the same thing, but going with a weird dual "physically individual" master cylinder system could get you into trouble. Especially if you were ever involved in a accident. The A3 style dual master cylinder is not that hard to find. "White Horse" trucks have used these master cylinders for over a decade now. I just bought another one off eBay for $80.00 . Brand new ! Same bolt pattern as the A3 style. The bore was a bit bigger but that is actually an advantage.

 

[Robo McDuff]

If you would do something like that, I would try to keep the two master cylinders as close as possible together, less tress on the pedal modification. But as mentioned by Rustystud, you might run into problems. Adding newer is probably easier to get certified.

With a 5-ton, it's probably easier to do.

My continuing problem is, if you split the brakes and use a new dual MC, how do you calculate which bore/size MC to use and how do you compensate for the split system so each half system gives the proper amount of power to its section?

 

[rustystud]

If you would do something like that, I would try to keep the two master cylinders as close as possible together, less tress on the pedal modification. But as mentioned by Rustystud, you might run into problems. Adding newer is probably easier to get certified.

With a 5-ton, it's probably easier to do.

My continuing problem is, if you split the brakes and use a new dual MC, how do you calculate which bore/size MC to use and how do you compensate for the split system so each half system gives the proper amount of power to its section?

Just use the same bore size as the A3 style master cylinder. Off the top of my head I believe it is 1-3/8" . Or is it 1-1/2" ?
All the master cylinders that fit our 4 bolt mounting will be almost identical in length, at least that is what I have found.

 

[goodwithwood35]

It’s 1-3/4” bore.


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[rustystud]

It’s 1-3/4” bore.


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Thanks. I knew there was a 3 in there somewhere !

 

[jacklegjim]

Started working on my m275 again
and the air pack and master cylinder
were leaking bad and I have the parts to fix it
but with the choice of parts being 30 year old
new or recently made parts from overseas
there is no way I could ever trust the single
circuit system. My other truck I put the split
system from an A3 on it and I am very happy with that,but
they are hard to come by and expensive.
So I decided to see if the single circuit bracket
could be modified. I did not include the winch lever
attachment part of the bracket because I don’t have a winch
and probably will never have one due to the cost.
I used the 3D model to get the need dimensions.
I will be using the master cylinder with the remote reservoir
But, the A2 style should work also.
I do need some detail on the heim joint and rod that attaches
to the brake pedal if some one has that.
The plate I made for the bracket has two 3/8 bolts
that will go through the frame at the normal mounting point
so a middle hole will have to be drilled in the frame and there are two
5/16 bolts on the other side that go through the bracket into the plate.
Please let me know what you think. To me it looks like it will work fine and be a safe
modification but I am not an engineer and do not want to create
a dangerous situation.

 

[rustystud]

Started working on my m275 again
and the air pack and master cylinder
were leaking bad and I have the parts to fix it
but with the choice of parts being 30 year old
new or recently made parts from overseas
there is no way I could ever trust the single
circuit system. My other truck I put the split
system from an A3 on it and I am very happy with that,but
they are hard to come by and expensive.
So I decided to see if the single circuit bracket
could be modified. I did not include the winch lever
attachment part of the bracket because I don’t have a winch
and probably will never have one due to the cost.
I used the 3D model to get the need dimensions.
I will be using the master cylinder with the remote reservoir
But, the A2 style should work also.
I do need some detail on the heim joint and rod that attaches
to the brake pedal if some one has that.
The plate I made for the bracket has two 3/8 bolts
that will go through the frame at the normal mounting point
so a middle hole will have to be drilled in the frame and there are two
5/16 bolts on the other side that go through the bracket into the plate.
Please let me know what you think. To me it looks like it will work fine and be a safe
modification but I am not an engineer and do not want to create
a dangerous situation.

That's looking pretty good to me ! Are you then going to remount it to the old bracket with bolts or welding it ?

 

[jacklegjim]

My plan was to remount it in the same place but two of the bolts
will be longer go through the bracket and thread into the new plate.

 

[jkcondrey]

Jackle, where did you get the dual master cylinder from?

 

[jkcondrey]

Would this be close to a working dual master cylinder versus the hard to get, hard to buy a3 master?

Hydro-Max Master Cylinder with 1-3/4" Bore (1.75 inch, early 80's Ford)

Item# MC-HM-1-3-4-FRD
$324.00









Product Description

11/16-18 and 3/4-18 ports

Hydro-Max Master Cylinder with 1-3/4" Bore (1.75 inch, early 80's Ford)

 

[jacklegjim]

Yes one like that would work. The master cylinder with reservoir attached are not hard to fine but,
it does need to be the right configuration. It needs to be 50% and 50% output.
It will need residual check valves in the port and the port size should be 9/16 -18 or 1/2-20 thread.
some of them have 3/4 port thread you would have a hard time making that work.

 

[rustystud]

Yes one like that would work. The master cylinder with reservoir attached are not hard to fine but,
it does need to be the right configuration. It needs to be 50% and 50% output.
It will need residual check valves in the port and the port size should be 9/16 -18 or 1/2-20 thread.
some of them have 3/4 port thread you would have a hard time making that work.

Actually the output of the master cylinder can be 60% , 40% . The dual system always runs the front brakes separate from the rear. Since the rear has 4 wheel cylinders and the front only 2 you could get away with a differential between systems. In fact I've been looking at this and most all systems that run front only, rear only systems always run a differential between them. Since I will be going with the larger A3 front brake cylinders on my truck I probably should use a 60%, 40% system . The fronts at the 60% and the rear at 40%. Also if your running the older brake boosters they already have residual check valves in them so that it is not required in the master cylinder.

 

[jkcondrey]

Rusty....so the short air packs do not have Residual valves? That's what I have on mine at the moment.