Simple Oscillating Cylinder Engine
This is first in a series of articles covering small model engines built by my father in his shed. See the whole series at Model Steam Engines.
This very simple oscillating cylinder engine was the first and simplest engine in a succession that increased in complexity and refinement each time. It was machined out of stock plate (no castings) and, like all the engines, was built ‘by eye’ – no plans other than the odd rough sketch on the back of an old envelope (it would have been a fag packet, but as you see from the video, there is no smoking here 😉
On this engine the end of the piston is directly connected to the crank ring with a peg that protrudes through a slot in the top half of the cylinder wall. As the crank rotates, the end of the piston follows the crank around which swings the cylinder on its pivot at the bottom.
At the bottom of the cylinder is a single hole which acts as both inlet and exhaust. As the cylinder swings to the left, this hole lines up with the inlet port on the mounting block, and steam/air enters the cylinder, pushing the piston up.
As the crank turns and swings the cylinder over to the right, the hole lines up with the exhaust port and the steam/air exits the cylinder as the piston moves down.
Click the animation to enlarge.
This is mostly machined out of some heavy aluminium plate, with a steel piston, crank and shaft, and a brass bush mounting the flywheel.
The pictures below show more details. Click to see full size gallery.