vacuum development in engine

downhill it runs, and it is engaged the transmission

Piston ascend makes blow (pressure)
PIston descend makes suck (vacuum)

Vacuum Engine is a new, powerful, economical, clean-running, automatic engine, capable of nearly global solar operation with likelihood of further engine development and endless free force potential available for centuries.

The four stroke; five event cycle.

Suck
Squeeze
Wow!
Bang!
Phooey