Having just finished the sketch of the oil pump shown on pages 19, 20 and a part of 21 of the document (Written in French) plus the translation of the text (Using
Free Translation Online), “Description Technique du MOTEUR D’AVIATION Hispano-Suiza”. one must arrive at some conclusion as to it’s effectiveness in a troubled lubrication system. Unfortunately the sketch in the book is very small, as is the type of the text, that a redrawing is necessary to understand just how the mechanism operates. Firstly it is a two lobe system of offset partial diameters. No dimensions are given.
The operating, revolving part is called a shutter (Pallette) and appears to be three pieces. The two pieces are spring loaded and slide against one another as the variances of the two partial diameters (circles) change in relation to the axis of the rotating shutter.
The one side of the chamber is shaped similar to a crescent and is the part that produces the extension of one side of the paddle.
This reason, paddle extension, may be the cause of Birkigt’s failure of putting an Oil Pressure Relief Valve in the system was the spring loading of the Paddle, he may have had cause to believe the spring would supply some pressure relief. However a simple test with heavy oil should have disproved this or he may have simply ignored the test. We will never know unless French documents are available to see if any tests were made of this type of pump.
Yours, M.L. Anderson
