Rotary Steam Engine 2

The latest Rumsey Rotary design has now been moved into Solid Works, and animated:

The first iteration was “printed” in plastic earlier this year, revealing some problems: the cam plate diameter needed to be much greater, in order to lessen the pressure angle and so  cycle the valve gates.  The smaller diameter cam plate seemed as though it would simply batter the cam followers to bits.  Now that the cam plate has become much bigger, it will also be necessary to lighten it; it will actually be closer to  the “skeletonized” cam plate in Rumsey’s original.  The animated design does not reflect this.  Also missing in the animation are the extension return springs, for the valve gates.

Update for 2023: Further study showed that the interaction of the cam and the slider valve cam followers was going to be quite tricky to manage. If the slider valve springs were too light, the slider valves would be lifted by steam pressure. If the springs were too heavy, the cam lobes would simply batter the cam followers. Increasing the length of the opening ramp over more degrees of rotation  of each lobe to minimize the battering would sap power- every degree would remove a degree of the power “stroke”. Seeing a much longer development process in front of us than we’d hoped for, we put the project on the shelf.

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