Author Topic: Douglas Patents of Note 09  (Read 8071 times)

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Offline Doug

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Douglas Patents of Note 09
« on: 14 Dec 2007 at 01:43 »

Improvements in or relating to Spring Frames for Cycles.

Patents of Note 09
Patent No.: 110,080
Application: Jan. 20, 1917
Complete: Apr. 10, 1917
Accepted: Oct. 11, 1917

Douglas patented several different designs for a sprung rear frame.  Besides the one using a leaf spring that was previewed in their catalog for the 1916 season (though apparently not put into full production), they also had a number of variations using coil springs situated in various locations and orientations.  This one was notable due to its similarity to the Draper system used on HRD.  While it would be tempting to credit Douglas with the prescience of the linkage used on modern mono-shock installations, the links B and E are there to provide lateral support to the upper part of the sub-frame A whilst allowing it to articulate with the suspension.  There is a separate patent for a variant with a recoil spring. 

There are no known surviving examples of this design, but an image appeared in a mid- to late twenties Motor Cycles and How to Manage Them of a 3-1/2hp fitted with a similar system. (However it seems to show a 2-3/4hp with unusual spark plug location.)

As well as a detail illustration in the section on sprung frames.

There is mention in an old NCR magazine that in the Motor Cycle, 8th July 1920, F.A.R. Zurcher appeared posed with a 3-1/2hp with identical rear suspension, on which he won the Durban-Johannesburg race (not seen.)

2007 D. Kephart, Glen Mills, PA, USA