Author Topic: Douglas Patents of Note 03  (Read 6478 times)

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Offline Doug

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Douglas Patents of Note 03
« on: 27 Oct 2007 at 01:33 »

Improvements in the Attachment of Engine Cylinders to Crankcases.

Patents of Note 03
Patent No.: 291,937
Application: May 17, 1927
Complete: Feb. 11, 1928
Accepted: Jun. 24, 1928

…principle object is to provide a construction which will provide give a firmer side support to the cylinder than usual…   Basically the cylinder is deeply spigoted into the crankcase, nearly half of it in fact.  Also part of the claim is improved cooling rendered to the (lower) portion of the cylinder and lubrication of the same.  The lower skirt of the cylinder, modestly finned (19) is partitioned off from the crankcase and oil circulated through the cavity (11).  The oil enters via (14) and returns to the crankcase via numerous drillings (15) Note too the numerous holes (20) to lubricate the piston.  The circular shape of the crankcase in Figure 3 is of interest, as indeed the whole crankcase construction shouts ‘theoretical’.

Cooling the cylinder with crankcase oil, though less flamboyantly described, seems to clearly infringe on Granville Bradshaw’s patent of 1921 for the same idea.  However Douglas got their patent accepted. 

In the accompanying patent illustration Figure 1, the lower half portion of the cylinder is sectioned.  Once this is understood, interpreting the drawing is a little easier.  Based on a description in Motor Cycling, October 19, 1932, Douglas planned to use such a cooling system on the proposed 250cc transverse twin “Gold Star”.  To the best of my knowledge Douglas never utilized this concept in any other engines.

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