Help understanding relationship of master cylinder to slave cylinder bore sizes

[Dallas]

Ron,
That was exactly my point.

This board is about helping and learning.

At least Brian put out a question to get the ball rolling. How do you know what questions to ask, if you don't have the knowledge to formulate the questions in the first place?

[kyle4501]

Gee Whiz, what a tough crowd.
I'm sorry if I have insulted anyone's intelligence 

I left out volume in the sentence "I would think it prudent to size the slave cylinder volume slightly larger than the master cylinder."

Ron,
That was exactly my point.

This board is about helping and learning.

At least Brian put out a question to get the ball rolling. How do you know what questions to ask, if you don't have the knowledge to formulate the questions in the first place?

Dallas, Just how are we supposed to let someone know the water is deeper than they thought? Based on the question, it looked like there was more he needed to know about.

The thing is, that as one who cares about fellow busnuts & their success, I was concerned that he may have been getting into a deeper pile of poo than he realized. I never said Brian couldn't or shouldn't do this & anyone that thought I did . . . Well all I can say is    
All i had to go on was his question, which led me to the reply I left.

Brian, I'd be happy to help you with this project, but like Ron said, we need more information. It doesn't have to be hard to do, but it isn't likely to happen by chance either with a few found parts. However, your reply:

Sean or Kyle,

Since I don't know what I'm doing are you volunteering to design my system for me?  Maybe I missed something between the lines .... as surely we should never attempt anything unless we are experts at it.  Or, maybe I should never have posted the question in the first place?

Leaves me wondering WTH?


I guess from now on we should reply to simple questions with simple answers  & just let fellow nuts waste money.  (For those that didn't notice, that last was was scarchasm)

[Hartley]

Just get a clutch master cylinder and slave from a 1961 International Scout. Or was that a 62 I had...?

Or Check with a fork lift outfit, Lots of the older forklifts used a master/slave hydraulic clutch
system. So the parts should be off the shelf for all of the above.

Then it's all a matter of how to hang it to get the right leverage and travel.

Sorry... It was getting way too technical and I gave up trying intricate math a long time ago.
( about the time I threw away my slip-stick )....

Dave the dummy !!!

[wrench]

       ONE moore here!!!!!!!!!!
 I think there is a missing data,, need to know how much force is require to fully depress the clutch lever,  & the distance between the foot pad & the master cylinder rod's center. I believe that if you have to push more then 15 pounds on the clutch pedal, it will be a hard/tough clutch.
      Not an engineer just a rigger        wrench
PS: If a soft pedal can not be achieved, I would try to design an electric power pump.

[kyle4501]

I just re-read the whole thread & Brian's question has been answered. Anyone that wants to share more information needs to wait until it is asked for. Otherwise someone will be offended. 

[wrench]

   Would happen that you would have an out date CAD software which can simulate movement? That would help me & my riggings!
                   wrench

[oldmansax]

You guys should watch your language!!!!!! Little kids could be reading this stuff!!!

In the first place, we don't need to know that Dallas isn't still "conversant"..... that's too much information...Dallas, you can probably get help from a professional for that....

And then there's all this business about "slaves" & "masters"! This is 2007, for crying out loud!!!! We should be trying to stamp out inequality wherever it rears its ugly head! Even in the engine compartment!

Now the discussion has fallen to the depths of depravity, simulating motions and whatnot.... When I was a kid we had to learn about that stuff the hard way! Now Ron does it for a living!!??

And lastly, this board should not be turned into classified ad space for the Sopranos..... Choking poor Arti for just $7.33! Who's going to take care of his family after he's gone?

Uh oh! Master's coming...us slaves better get back to work!!

[Sean]

Sheesh, I go away for a few hours, and I come back to a firestorm.

It was not my intent to offend Brian or anyone else.  If my words came across that way, I apologize.

Please note that (1) I answered the original question and (2) I provided links to resources for Brian to become educated on the subject.

That being said, I stand behind my original statement, which questioned the wisdom of designing a hydraulic control system without fully understanding the mechanics, and the possible consequences.  And, no, I don't think it is at all comparable to building cabinets, as someone suggested.

We are talking about piloting coaches weighing upwards of fifteen tons -- these are machines of awesome power and the consequences of getting critical control systems wrong can be devastating, up to and including people dying.  For that matter, even an automobile is potentially a lethal weapon.  So I do not think it is unreasonable to expect that anyone on this forum, or anywhere else for that matter, should have a basic understanding of control systems BEFORE altering or building them, or even, in many cases, repairing them.  Which is why I made the statement AND provided the links.

Would you board a commercial motorcoach if you knew, say, that the steering had just been worked on by mechanics who were not trained to do so?  How about an airplane?

There is a whole lot more to making a hydraulic clutch or brake system work that just knowing the basic relationship between piston area, pedal force, and travel.  One needs to understand factors such as the compressibility of the working fluid, the coefficient of thermal expansion, the working pressure of the system components, and the loads that will be presented to the operating cylinders at both ends.  Even the loads on the mounting hardware need to be calculated and the hardware sized appropriately.  When these systems are designed and specified by the OEM, they are engineered by a professional engineer with access to all the data.  Even then, sometimes things go south, and the manufacturer has to re-engineer something -- hopefully during testing, but we've all heard about recalls because mounting systems failed over time, or hydraulic lines tended to spring leaks right over hot manifolds.  Modification in the field carries an element of risk, and you'd better know what you are doing if you contemplate it.

So, Brian, I intended no offense, only advice.

-Sean
http://ourodyssey.blogspot.com

[rv_safetyman]

Brian, as Luvrbus pointed out, I have been working on this issue for a while.  Indeed, I think you and I talked about this on the phone once or twice. 

When I started, I used all Volvo truck parts.  I had to modify the clutch pedal leverage a bit to make it all fit under the Eagle dash.  It was a b*^$h to push.  Also, I could not get the reservoir to fit and made a stab (didn't work) at a remote unit.

So, I started over on the master cylinder side.  A member of the Eagle group had developed an air over hydraulic system that seemed to work great.  He used a regular car master cylinder and a air brake can to actuate the master cylinder.  I have been playing with that concept as well as a mechanical hand lever system (does not work well at the toll booths, duh ).  The hand system did work well, but was not the answer I was looking for.  I have tried to design all kinds of pure hydraulic linkage systems, but there is not much room in the front of the Eagle. 

I will be installing the third master cylinder in the next week.  I have done all of the calculations, but it still came down to cut and try.

The one thing I did mention in a previous post was to be sure to use a two wire hydraulic hose for the run from the front to the back.  You do not need it for the pressure (less than 800 PSI with my present system), but you do need it to minimize the expansion of the long hose and the associated loss of control.

Have fun! Jim

[prevost82]

I guess that's the last time I offer too help. I'll go back to my hole.
Ron