Observation
Thought this might be considered ancectodal evidence, I must say that I drive, on a daily basis, a vehicle equiped with hydraulically-actuated, four-wheel drum brakes, of the dual-servo, self-adjusting type. Since re-shoeing all four wheels several thousands of miles ago, I have, in a wide variety of braking conditions, experienced no brake fade. Could it be the modern linings?
I also wish to point out that the brakes lack power assist, which the servo action seem to make up for, and, that braking control driving on ice and snow was much better than what I have experienced on ABS and non-ABS power-assist front disc/rear drum equiped vehicles.-WK-139.78.96.115 01:13, 8 March 2007 (UTC)
Yes, it is a 1968 Chevrolet truck.-WK-139.78.96.83 22:23, 20 March 2007 (UTC)
Rewrite
I hope you can accept what I have done to your "brake fade" page. Having worked on disk brake development and working with tribology (friction and wear) I came across the items I mention in the rework of that article. The gas bearing and drum expansion are things mechanics, not engineers, cooked up and it is obvious because servo effect is not part of their technical understanding. Jobst 06:40, 17 February 2007 (UTC)
I think you should re-read what I wrote and tell me what part you don't understand. The article as it was is based on myth and lore, that you cite from a popular magazine. That is not a valid citation, only a repetition of what you have repeated. I explain why the gas bearing hypothesis is false and defies all reason. Having worked on disk brakes in high performance cars from the outset of disk brakes I can explain how this works and did so. If anythinng, you should show proof that expanding drums and gas-bearing exist. As I mentioned, disks operate at red hot temperatures, ones that gas bearing drums never did, using similar friction material. You should also consider why drums were discontinued when friction materials that cannot out-gas have been designed. Jobst 03:39, 18 February 2007 (UTC)
I don't understand what you mean by "you are not the source". The part that you offered is documented more sparingly than mine and as I pointed out, defies physics. That is why it caught my attention. You refer to WP:PILLARS in which is stated:
That you restored the old version seems to indicate that you believe it is correct. I suggest that you give proof that drum expanding or gas bearing causes brake fade. The references listed are not technical support for this physically impossible hypothesis. If you are skilled in the design of brakes you shoudl recognize what the downfall of drum brakes is and why we no longer have brake fade. You shouldn't take this personally and feel insulted but you should also not pass on folklore as encyclopedic information. Jobst 04:25, 18 February 2007 (UTC)
To make the point that you are repeating auto lore, I have asked for references on a few of your unsupported claims. Alternately you could explain how these things occur and their cause instead, but you do neither. Especially the gas bearing item needs explanation or proof, that being a lot of gas with no apparent source. Remeber, after cooling, faded brake pads show no sign of having lost gas or otherwise changed permanently. In fact, they will do it again if put to the test.
Please give what I wrote some thought. Also your talk of high performance equipment has nothing to do with the causes and remedies of drum brake fade. Jobst 05:04, 18 February 2007 (UTC)
As you see, justanother , the anonymouse author of this piece, shows no reasonable explanation for the effect of brake drum expansion causing fade, the Coefficient of thermal expansion being vanishingly small in comparison to normal ovalization of drums by braking forces. The gas bearing scenario cannot be found in Dunlop, Girling, Lockheed or any other brake manufacturer's literature. It is folklore. The volume of gas required for such an effect cannot come from friction material, once or repeatedly, brake fade occcurring again as easily as the first time. The citations listed are auto enthusiat magazines, neither of which explain what these gases are and how they keep coming out of brake pads that were originally formed at high temperature in manufacture.
Brake fade is unique to drum brakes because they use self servo action (leading brake shoes) ] whose servo effect relys on the proper friction coefficient, one that reduces at elevated temperatures. I request that justanother cease deleting my re-write of this article and not continue purvey myth and lore. Please note the notations in the article. Jobst 18:31, 19 February 2007 (UTC)
Dear justanother,
Deleteing callouts in your article is not the way to respond to requests for verification of what is known by people in the indstry to be myth and lore. Jobst 19:15, 19 February 2007 (UTC)
justanother, I beg to differ. Having worked in the disk brake business I am aware that these folklore stories of gas are some sort of widely believed cargo cult, even though there is no credible explanation, nor any analysis of its existence. You won't find a technical source for proof of the gas bearing or brake drum expansion theory. On top of that, not much is being written on drum brakes these days, except the repition of the gas theory. Please review what I wrote and the proof I gave about drum brakes operating in a narrow friction coefficient between lock-up and fade. How does the gas hypothesis explain drum brakes locking? Jobst 20:07, 19 February 2007 (UTC)
Maybe I'm unclear on the concept, but who is entitled to place references in articles? From my experience it seems to be as open as the rest of Wiki. One of my previous articles was riddled with them even where there were plenty of references. After that the article was deleted by I don't know whom although I can guess from the threats that preceded.Jobst 00:03, 20 February 2007 (UTC)
Justanother, the only thing you really need to do is stop writing unsourced material. If you add something then provide a source so that othere editors can check your work. That is how it works here. If you will do that then you will find that your contributions are welcomed here.
That your article is backed up mainly by another's repetition of drum brake lore does not seem to stike you as odd. That citation contains no explanation of what causes fade, only that it is caused by thermal expansion and gas generation, both of which have not been shown to exist. This is a hypothesis from brake mechanics, not an engineering staff at a major brake manufacturer. Repeating it from auto magazines does not make it credible. We don't need Wiki's to repeat such stories when you can get that from the man on the street.Jobst 03:37, 20 February 2007 (UTC)Whether it is your article or not, you seem to be its sole defender and thereby assume authorship. Bluntly, it is erroneous and false. Apparently you didn't read the referenced study in which among other findings the following is mentioned:
By reinstating your brake folklore article you ignore logical explanations that should have dissuaded you from the belief in the drum expansion and gas bearing hypotheses, neither of which are physically possible. Editing and elaborating on these fables does the readers of Wiki a disservice. This is not a forum for myth and lore. You have shown no explanation how drum expansion and gas bearing cause fade or that they do so. What I wrote, as well as in the reference citiation from a scientific journal explains how the servo effect of drum brakes causes brake fade.
Is there no one else reading thse pages with comments on the subject? Jobst 20:49, 20 February 2007 (UTC)
You say you are not the author but you expanded the article to have more sections, mostly not about brake fade and its cause. Since the introduction of disk brakes, more than 30 years ago, fade has no longer been a concern to drivers, making the other parts of the article irrelevant.A single Brake Fade heading will do, fade being unique to drum brakes and its cause their servo effect. My article recalls the vagaries of servo effect that cause both fade and lock-up. I don't see what part of the existing article you propose to keep.
The report I cited appeared in a peer reviewed Michigan State University technical publication. Your ad hominem of the author is out of place. This is not an auto magazine with conversational fare.Jobst 22:27, 20 February 2007 (UTC)
Bendix sources and other sources to improve the article
"Brake fade - There are many types and causes of braking fade. Fade may result, for example, from a reduction in friction between linings and drums caused by exposure to water. Most typically, however, fade involves a reduction in braking force experienced when dragging brakes on a long grade. If brakes are maladjusted, and overheated drum may expand to the degree that push rod travel is insufficient to fully actuate the brakes. This is one example of mechanical fade, which also may result from various mechanical defects (e.g., scored drums) within the foundation brake system. In contrast, heat fade occurs when linings overheat and become less aggressive. Gradual and predictable fade is desirable as a warning."
"At Bendix Spicer Foundation Brake, we developed the metallurgy in our 17-inch rotor and paired it with our advanced friction material specifically designed to optimize frictio
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