The first disc brake, part 3
previous DISCussion of early disc brakes here: https://occhiolungo.wordpress.com/2013/10/07/the-first-disc-brake/
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…
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.