The Yoke Drive

The success of the small alpha produced a burst of activity. By December of 1976, I had devised the yoke drive mechanism (now generally referred to in the literature as the "Ross linkage") and a method to dynamically balance it (US Patent 4,138,897). The 15cc alpha engine was immediately modified to incorporate the yoke drive, and it performed as well as ever, but not noticeably better, as I had hoped it would. By January of 1977 I had begun a 50cc yoke drive engine that would employ the existing insulation dome, heater, regenerator, and burner of the 65cc rhombic. After the discouraging activities with the gamma engine, I needed some promising new path to follow, and the yoke drive seemed to be just that.

The yoke drive consists of a triangular yoke mounted on a single crankpin, and guided by a rocking lever. The combination of the circular motion of the crankpin and the arc of the rocking lever produces nearly linear motion at the extended arms of the yoke, with a phase between the motion very suitable for an alpha type stirling engine. The three major advantages of this drive mechanism are: 1) very low piston side loads, permitting long life and low friction with oil-less operation, 2) closely spaced parallel cylinders, which are easily connected with compact heat exchangers, and 3) relatively small size and low weight for a given swept volume. The use of a single counter—rotat­ing balance shaft will put the engine in complete primary balance, or, the engine can be partially balanced without the extra shaft if some vibration can be tolerated.

During the construction of the 50cc yoke drive engine, I was sure that I had finally found a way to make a simple stirling that would perform well. When it was finally far enough along for an initial test, I wasted no time. The engine was fired up, and when the heater was red I flipped the flywheel. The engine ran, but rather slowly. It built up speed, but again rather slowly. After what seemed like 5 minutes, but was more likely only several minutes at most, the engine still did not seem to be performing well at all.

Variations of the Yoke Drive or Ross Linkage

The original version


The Yoke Drive The Yoke Drive The Yoke Drive The Yoke Drive

The Yoke Drive

The compact Inverted Yoke Drive.


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The Cable-Driven Yoke Drive.

подпись: the cable-driven yoke drive. The Yoke Drive

The Yoke Drive

The Rocking Piston Yoke Drive.

The Yoke Drive

The 50cc yoke drive engine.

The Yoke DriveThe 15cc alpha with yoke drive, shown with the 11cc rhombic.

The Yoke Drive

In disgust and frustration, I shut it down and put it on the shelf.

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