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The first disc brake, part 3

November 18, 2013

previous DISCussion of early disc brakes here:

and here:

Now we are getting somewhere!  Simon Harland, director at the National Motorcycle Museum in Birmingham England wrote in to share a photo of their 1906 Imperial 500.  This is the bike with the cable operated rear disc brake.  And it is a real disc brake too, with a pair of caliper pads that squeeze axially onto the disc.  A scissor mechanism converts the cable pull into equal opposing clamp forces of the arms and pads.  No word on what the materials are, but my engineering materials research has shown that lead pads rubbing on iron produces a very high coefficient of friction…

241 Imperial 1906 - Copy

Looking at the photo, the bike has other novel engineering features too.  Note the location of the valves, out in front of the cylinder.  And the seat brackets are something. The lever mounted to the frame top tube just ahead of the seat is the throttle, which was common in 1906, but this one operates through a Bowden cable instead of a linkage rod.  And the stirrup which holds the cylinder head to the crankcase predates the common usage by AJS.


So, can anybody find a disc brake that predates 1906?  If so, please send us a note via the “Comments” button below.

20 Comments leave one →
  1. Rick Yamane permalink
    November 19, 2013 8:14 am

    Pete, you don’t think they would have just used an adaptation of whatever the conventional brake lining was of the time?

    • November 19, 2013 9:01 am

      Sure, most likely. The teens materials that I’ve found useful on band brakes were lead woven into asbestos fibers. Dummy rims used a rubberized material that gripped OK and wore well. In some ways we have less choices today, as lead and asbestos are verboten in many places. But we can find bits of old material via the swap meets and find some neat new materials via the internet. 🙂

  2. Jim Abbott permalink
    November 19, 2013 9:31 am

    Pete: There is nothing new under the sun! Jim A.

  3. November 19, 2013 12:49 pm

    The cylinder clamp is interesting. It doesn’t have a detachable head, does it? After a friend of mine blew the head gasket on a Mk1 Square Four pulling a Plymouth out of a ditch, he rigged up some steel plates across the top of the head attached to the frame with turnbuckles. Can’t remember exactly how he did this (45 years ago), but it was interesting. It didn’t work, either.

  4. November 19, 2013 1:57 pm

    This is an open question due to my total ignorance on the matter.
    When was cork first used? and permit me to amplify the question to “Ferode”. Perhaps it is out of the line of conversation but your posts have raised my curiosity – Please don’t kill any cat around 🙂

  5. November 20, 2013 8:27 am

    I like the 1902 photo on their site: coal-fired, steam-powered, belt drive saw-tooth roof mill making friction linings out of asbestos and other good stuff. Must have been a great place to work!

  6. Sidecar Bob permalink
    January 16, 2015 4:24 am

    Doesn’t a bicycle caliper brake qualify as a disc brake? The caliper’s rubber pads act on opposite sides of the rim…

    I don’t know if they were ever used on motorcycles but with a patent date of 1887 they certainly predate 1906.

    • January 16, 2015 10:23 am

      Agreed, the caliper brake IS a disc brake, utilizing the rim as the disc. I’ve only seen them on mopeds, but it wouldn’t surprise me if an early motorcycle builder used them.

  7. April 23, 2015 7:39 pm

    Often the FIRST of something doesn’t look much like a modern or developed version. What we must do is think of how it works, what are the advantages over what came before. Looks are secondary. The “Simon Hartland, NMM” image is of a reasonably developed disc brake, but I still think the Douglas Research brake qualifies as a disk brake. It has a disk, (NOT a rim pulley); it has a caliper, whichever way it moves; and it is separate from most of the wheel itself, which separates it from cycle-type caliper brakes. I agree there may be other earlier disk brakes than the Douglas, and I don’t have a reliable time for the Douglas, but it fits in there somewhere.

    • April 23, 2015 8:43 pm

      My problem with the Douglas RA brake is that the only moving part (whether you call it a shoe or a caliper) does the exact same motion that all the other common brakes did at least 10-15 year previous to the RA. Douglas just used friction material on the dummy rim, and used steel on the moving shoe. Change those materials vice-versa and it is essentially identical to all the common brakes going back to the turn of the century.

      But when we look at a real disc brake caliper, it has two moving parts that come towards each other to grip a disc. In my mind, any brake with only one moving part doesn’t have a caliper. So I’ll keep thinking that the Douglas RA is not a disc brake. 🙂 If we say that the Douglas RA is a disc brake, then so was the Triumph, the BSA, the Premier, Douglas, and nearly all the British and European bikes from 1905-1925. They all had the same design.

      • April 23, 2015 9:09 pm

        You can think what you want, but I don’t think your arguments are valid. You are talking about a developed disk brake. I am talking about one of the first, whether in time or mechanical development. Good day

      • ricoyam permalink
        April 24, 2015 10:08 am

        Does anyone have any photos or drawings of the Douglas brake? From the photos I’ve seen it looks more representative of a drum without seeing what is going on inside. Of course it’s kind of moot since the Imperial brake appears to predate the Douglas by around 15-20 years.

      • April 28, 2015 9:15 am

        Hi Rick. We missed you in King City last week! 🙂 There isn’t anything inside the Douglas RA brake. It is just a rim with an external moving shoe that rubs against it. Douglas made the rim (or disc if you’d like to call it that) from fiber/abrasive braking material (Ferodo or similar), and made the moving shoe from metal. The standard design used by everybody else was a steel rim, and braking material on the moving shoe. Since the Douglas brake rim is smaller diameter than other marques, and since it is a bit thicker than others, it looks somewhat like a disc. That is where the confusion began a few decades ago when people said it looks like a “disc” brake. There is a photo and description of the Douglas RA brake on this page:
        Douglas RA brake

      • ricoyam permalink
        April 28, 2015 9:44 am

        I’d be hard pressed to accept the RA brake as a disc brake after seeing them. There must be a better term to describe those. It’s true the rotor is a disc of sorts but the shoe itself cannot be considered a caliper and it does not clamp the disc as much as it simply pushes against it.
        More of an external V-drum I’d say.

        Yeah, I’m not on the list of invitees for the King City Ride. I don’t have a bike that old, although Victor said he’d allow me to show up on my Rocket Goldie. I’m looking for a pre-war bike but I’m also thinking it’s a major investment for a bike I’d probably only ride 2-3 times a year. Something Italian or British with a girder fork would nice even just to look at though.

  8. Sidecar Bob permalink
    April 24, 2015 2:52 am

    Before there were disc brakes calipers were measuring devices (look it up). The brake caliper no doubt got its name because it pressed against the sides of the disc in the same way that a caliper would when measuring the disc’s thickness. This absolutely precludes a tapered shoe that is forced against the edge of a ring with matching taper from being in any way, shape or form a caliper. As Pete said, it is merely an inverted form of the same thing as a brake block rubbing on a pulley, nothing more.

  9. Philip Vier permalink
    September 23, 2015 3:49 pm

    I have a very clear photo of my maternal grandfather, NYC Motorcycle Division Police Inspector, Anthony Leo Howe (in his police uniform) standing alongside of what I believe was a 1904 Indian “Single” that has what looks like a front wheel disc brake system. I would be glad to provide a copy of this photo upon request.


  1. First Disc Brake, continued (National Motorcycle Museum) | Occhio Lungo
  2. The first disc brake? | Occhio Lungo

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