This engine is not a "vacuum" engine, it is a "beta" type stirling engine. Beta means that the power piston and the displacer are both working in the same cylinder. This arrangement gives greater power output than the typical two cylinder engine. The reason for this is that the compression ratio can be higher due to less "dead" space inside the engine.

The Duplex Vacuum Company of Chicago, Illinois made this type of engine about 100 years ago. They were widely used in popcorn wagons and to operate dental drills among other applications due to their silent operation and reliability.

A unique feature of the Duplex engines is the oscillating shaft and linkage which produces an interesting motion in operating the displacer.

The plans set consists of 8 sheets of drawings and 2 sheets of construction and assembly notes.

Specifications: Bore: .750", Stroke: .750", Flywheel Dia.: 3.750", Height: 10-5/8" Experience Level: 7

Materials Set: (1) Graphite rod to make piston, (2) 3/16" ID x 3/8" OD x 1/8" thick precision ball bearings.  Materials set sold separately.

"I would like to thank you for all your years of coming to the PRIME Exhibition, you were always one of the most popular builders and your work is so beautiful." - Ram Meier, PRIME Expo (Eugene, Oregon)