Reply to "Yella Terra YT6015"

mpaschettoMember

Hi George,

I drew up a quick 3D model of a rocker arm and a valve in SolidWorks:

In this model, the rocker arm is constrained to rotate about the centerline of the trunnion. The valve is constrained to move in a linear fashion along its axis. The valve stem tip and rocker arm tip roller are coupled together with a tangential 'mate'. This mimics the components as they would be installed in practice.

I set about to compare the differences between two distinct valvetrain geometries, I'll call them Method 'A' and Method 'B'.

Method 'A' establishes midlift geometry using the point of contact between the rocker arm tip roller and the valve stem tip.

Method 'B' establishes midlift geometry using the centerline of the rocker arm tip roller. This is the preferred method of Jim Miller.

Method 'B' produces a smaller, symmetrical sweep pattern at the valve stem tip. With any luck, the PDF file I've attached can be downloaded for a more legible drawing.

I hope this quick analysis can help anyone that's bothered to read this far... ;-)

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Geometry Comparison.PDF

1/26/2011:39 AM

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