Improvements in the Crank-cases of Internal Combustion Engines.
Patents of Note
06Patent 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
