Author Topic: Douglas Patents of Note 06  (Read 5675 times)

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Offline Doug

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Douglas Patents of Note 06
« on: 30 Nov 2007 at 02:32 »


Improvements in the Crank-cases of Internal Combustion Engines.


Patents of Note 06
Patent No.: 15,313
Application: Jul. 03, 1913
Complete: Jan. 15, 1914
Accepted: Jul. 02, 1914


I suppose the most noteworthy aspect of this patent is that the engine has reached such a recognizable form of its final state, a year before it was cataloged for sale.
 
Complaining of the usual design of the horizontally opposed twin having the crankcase split vertically making access to the crankshaft so difficult, Douglas is patenting dividing the crankcase into three horizontal sections, one joint being on the axis of the crank.  Difficult or not, Douglas used horizontal division only on the 3-1/4 and 4hp models and persisted with the vertically divided crankcase for everything else! 

The cylinders are oddly described as “…being fitted with overhead valves…” but this means ‘above the cylinders’ rather than O.H.V. heads as we know today.  Particularly as they go on to describe the cambox position above the crankcase and its convenient proximity to said valves.  Possibly the acronym O.H.V. had yet to be coined.  Item 10 shows slots in the cylinder base flange to allow removal of the upper half of the crankcase without disturbing the cylinders.  Not something that I think was put into practice unless they did it just on the early 3-1/2hp models. 

Patent 15,322 applied for the same day covered the dovetail clamp feature of the crankcase base to frame.  Patent 17,744 applied for in August of the same year covers the early Archimedean oil pump employed.  Further patents separately cover the clamping the gear case to the inclined surface of the crankcase base, mesh oil tray strainer, and sump clean-out plug. 

© 2007 D. Kephart, Glen Mills, PA, USA

Offline graeme

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Re: Douglas Patents of Note 06
« Reply #1 on: 30 Nov 2007 at 04:47 »
Doug,
Yes there are vertical slots in the barrel flanges of the 3 1/2 cylinders. I'm not sure if this carried on to the 4hp - I'll look at the spare engines under the bench.
Graeme

Offline Doug

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Re: Douglas Patents of Note 06
« Reply #2 on: 01 Dec 2007 at 00:44 »
Graeme,

I have a 1918ish 4hp engine, and that does not have slotted cylinder base flanges. So I figured it was an idea they did not use, or it was restricted to earlier models. I would think slotting vertically that way made the base flange very weak.

-Doug

Offline graeme

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Re: Douglas Patents of Note 06
« Reply #3 on: 01 Dec 2007 at 07:14 »
Checked the spare engines Doug - the earliest no 4hp engine has the slots, later ones don't.
Thankfully neither of the 3 1/2s have blown their barrels off - but I agree, it would have to be a weakness. And in practical terms it doesn't work either - well not with modern sealants used on the base gaskets! I know this from experience trying to dismantle the engine as per the book.

Graeme

 

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