Talk:Disc brake

From Wikipedia, the free encyclopedia

Reverted User:AdamS's capitalising of the 'A glowing disc brake' caption because, since headings aren't supposed to have other than initial caps, so should picture captions. —Morven 10:03, 21 May 2004 (UTC)

Contents

[edit] Motorbikes

This page is awfull there is almost no mention whatso ever of motorcycle disk brakes, which are completly diffrent from car ones. There is also next to no mention of the matreials used or their structure ect, sorry but this page is poor and almost useless. someone sort it out. —Preceding unsigned comment added by 172.142.163.122 (talk) 10:42, 2 December 2007 (UTC)

[edit] Full-Circle/Annular brakes?

User:24.21.241.47 added a large discussion of "full circle" disc brakes including a single external link to a company that makes (?) them. Sounds like a real technology, but has never been mentioned by autoweek or ward's. Google didn't have anything like it in the top 10 in a search for '"full circle" brake'. I've never heard of it. I removed it. What do you all think? Reminds me of Quasiturbine... --SFoskett 03:13, Jan 28, 2005 (UTC)

Exactly. Come back when people have heard of you. —Morven 10:01, Jan 28, 2005 (UTC)

they're called "full contact disc brakes" http://www.newtechbrake.com/ http://www.carbibles.com/brake_bible.html —The preceding unsigned comment was added by 62.80.224.238 (talk • contribs).

Wasn't that in PM or PopSci a few yrs ago, a spl ish on "future car" tech? (Anybody remember what ish that was?!) Trekphiler 17:38, 21 August 2007 (UTC)

[edit] In wheels?

The picture caption states "On automobiles, disc brakes are located within the wheel". Is that always the case? Doesn't Jaguar use a rear axis where the discs are located almost at the differential? // Liftarn

Good catch - inboard brakes. --SFoskett 15:46, Apr 6, 2005 (UTC)

[edit] Recent additions

Do some of the recent additions/changes seem a bit dodgy to anyone else? At a minimum, there's now grammar cleanup that's needed, and I'm not sure I agree with the technical accuracy of some of the changes.

Atlant 20:28, 7 September 2005 (UTC)

[edit] Concerns about runout

I'm new here, so I was hestiant to make changes myself, but I agree. Particularly, the setench about how .007 inch thickness variation can be felt - this is entirely dependant on the rest of the braking system. I was going to change it to this:

The thickness variation can often be felt by the driver when it approaches or exceeds the maximum allowable value specified by the manufacturer.

but thought I should get some feedback here first, seeing as I'm new :)

--Emesis 16:08, 19 March 2006 (UTC)

You might keep the data that's there now by including something like: "when it approaches or exceeds the maximum allowable value specified by the manufacturer; .007 inches is a typical maximum value allowed."
Atlant 16:44, 19 March 2006 (UTC)

[edit] Disc Brakes on Bicycle

There is a lot of inforation about disc brakes ane how they are used for motorised vehicles (e.g. cars), but how about disc brakes used on bicycles, because surely they are not the same.

Actually, the basic operating principle is identical; only the implementation details vary. You know: master cylinder, hydraulic fluid, caliper, disc. But please, be bold and add to the article as you see fit!
Atlant 16:46, 19 March 2006 (UTC)

Bicycle disc brakes work in an identical way to cars, in that they all have a master cylinder, a disc (known as a rotor on a bike) and a caliper, interconnected by brake fluid, which operates the pistons. The main difference is the mounting and the overall size and weight of the brake. The bicycles' rotor is mounted on the wheel therefore making it easier to replace the brake pads. Also, the brakes are considerably lighter, approximately 300 grams for each brake, although this excludes the rotors. The size of the rotors also differ, from 140mm to 225mm in diameter. The brakes are not vented either unlike a car that has effectively two rotors attached with a gap in between, although new brake designs are being released by the likes of Hope Technology, which are vented. All bike rotors are cross-drilled, reducing the build up of gasses which can affect braking performance, and it also helps to keep both the pads and the rotor cooler, by increasing the surfac area they have to cool down. —The preceding unsigned comment was added by 82.19.153.145 (talk • contribs) .

[edit] Cross Drilling

I added some information about cross-drilled rotors under the "Discs" subsection. I'd like to add something somewhere that brakes work by converting the car's kinetic energy to thermal energy; a dramatic illustration of this can be seen here: http://img.photobucket.com/albums/v306/RiddleFox/cars/RedHotBrembos.jpg Just not so sure where. Riddlefox 21:03, 6 April 2006 (UTC)

'Sounds like an item that belongs near or in the lede. Of course, one might also argue that that's info that's already in the cross-referenced (I hope!) article on plain-old-brakes. ;-)
Atlant 23:35, 6 April 2006 (UTC)

What's that nonsense about "heat dissipation"? Cross-drilling does not improve heat disssipation. Quite the opposite, disk brakes with cross-drilled disks are more prone to overheating due to lower contact area and, consequently, higher heat accumulation in the pad.

—Preceding unsigned comment added by 198.182.56.5 (talk) 20:03, 19 May 2008 (UTC)

My understanding is that the real purpose of cross-drilling or cutting grooves is to dissipate offgasing that occurs under severe braking. Since the heat dissipates primarily through conduction and then convection, the drilled holes may actually restrict the flow of heat through the rotor disk. The vents in vented rotors adds convective heat transfer to the cooling process.--THE FOUNDERS INTENT TALK 13:24, 20 May 2008 (UTC)

[edit] Bedding Rotors to reduce Squeal

Pad and rotor bedding procedures are often overlooked by drivers. In performance automobiles, properly bedding new pads in old rotors is essential for performance, comfort and squeal reduction. Is it appropriate to add a procedure to the article? Wpjonathan 13:27, 11 April 2006 (UTC)

Unfortunately, it is unrealistic to expect most drivers to go through the complicated and time consuming process required to bed the pads. 500 miles (as I have read in one source) is rather long to expect the average driver to pay attention to bedding pads. Frankly I wouldn't expect my wife to drive more than 5 miles before she decides it's been long enough. --THE FOUNDERS INTENT TALK 13:28, 20 May 2008 (UTC)

[edit] Brake repair and maintence

Having recently shelled out ~$90 to replace a "brake switch" I'd like to see more general information on the parts that go into the brakes and how to replace/repair them. So if someone could add a section for this, that'd be nice. Also, after poking around a bit most places seem to have "brake light switches" for about $3 and they go into the main fuse box under my hood...takes a good 3-4 seconds to replace it. Am I getting hosed on this deal or is the "brake switch" something different? -Anon 12:33, 2 May 2006 (CST)

Old joke:
The big factory has been shut down for a while, costing the company millions of dollars a day. They call in the consultant who arrives, looks at the situation, pushes one switch, observes the factory start working again, and presents his bill: "$50,000 for services rendered".
The CEO says "That's outrageous! I won't pay it! Break it down so I can see just where my $50,000 went!"
The Consultant re-writes his bill:
  1. Pushing Switch: $2
  2. Knowing which switch to push: $49,998
You're kind of in the same boat. By the way, I doubt the replacement switch was $3, but let's say it was $10. Where did your other $80 go? It went to knowing what part to replace and how to replace it correctly. For some switches (the mechanical kind that are operated by the brake pedal lever), that means knowing how to adjust it. For others (the hydraulic kind), that means knowing how to replace it without introducing dirt or air bubbles into your brake fluid or knowing enough to bleed the brake system afterwards.
Brakes are pretty serious stuff; you do want the technician who works on your brakes to know their stuff, right? ;-)
You may also have been hit with a "minimum shop time" charge. When my Audi dealer works on my car, the minimum workshop time is one hour at $90/hour. no matter how long the repair takes. But no matter what type of brake switch you had, you can trust that it probably took more than "3-4 seconds".
Atlant 17:52, 2 May 2006 (UTC)

[edit] Early History

Crosley's '49-50 discs were not "a type of" but true modern discs: http://www.ggw.org/~cac/Images/Misc/DiscBrakes-Sm.JPG Examination via a '35-53 MOTOR manual diagram further proves this fact. The apologetic wording "type of" needs to be stricken. Sorry, Jag. Imperial's '49-53 disc brakes should by right be mentioned, though those DO fit the billing of being "a type of", as they were fully enclosed with dual expanding full-circle pressure plates. WQ59B 03:02, 16 June 2006 (UTC)

 yes but they were fixed brakes that also floated, they were fixed directally on but relied on one piston contacting the rotor first then pulling the other one in... believe me that was my uni thesis for engineering science.
 So yes they were the first "modern brakes" however they were not under the general specification headdings and so are not recognised.

[edit] Pad retraction?

  • How do the brake pads retract after application - are springs or negative hydraulic pressure used? What stops the brakes staying "on"? 59.167.41.84 06:46, 8 December 2006 (UTC)
They don't ever really retract (well, more than an infinitesimal amount). It's just that once you stop putting pressure on them (with the brake fluid or air pressure), they have no normal force relative to the rotor surface and so they exert essentially no friction force on the rotor. And the slight non-planarity of the rotors then drives the pistons back an infinitesimal amount, leaving a slight clearance with the rotor except at the rotor's "high spots". That the pads remain almost in contact with the rotors is actually useful as it helps to keep the rotor "swept" of any significant thickness of water and also prevents the intrusion of sand, grit, and other road debris.
When you finally change out worn pads and rotors, you use a clamping mechanism (of various sorts) to force the pistons back into the calipers. (Or, for calipers equipped with parking brakes, you often screw the piston back into the caliper.)
Atlant 12:42, 8 December 2006 (UTC)

[edit] DTV?

One of the sections near the end makes reference to the acronym 'DTV' but it's not readily apparent what this is. Either I'm blind or the article could use a bit explaining it :) Ayocee 16:41, 27 April 2007 (UTC)

[edit] Liquid cooled disc brakes

One of my friends has developed a liquid cooled disc brake ("liquid cooled drive line" I think is the official description) called the "D-Brake." It attaches to the tail end of the vehicle's transmission and applies braking force to the drive shaft. Is this technology worth noting in the article? I don't know if this is the first of its kind or not, but I have detailed information available should it be deemed noteworthy. --Jack 22:27, 3 September 2007 (UTC)

[edit] Use on trains

This article completely overlooks the use of disc brakes on modern passenger trains a "hole" that needs to be filled by an expert in the field. Peter Horn 14:23, 26 March 2008 (UTC)