Steam Engine Restoration Part 8 - Assembling The Piston and Packing the Seals

The first step of the mechanical restoration was to replace the piston rod that had rotted away from rust. I purchased a piece of steel rod from McMaster with the same outer dimensions, and since I cannot cut threads on my lathe, I had a machinist friend make an exact copy 

Raw material next to the original

Finished copy

Installing the rod was the next step. I pulled the head off the cylinder, installed the rod through the hole in the bottom, installed a lock nut, and screwed it into the crosshead. 

Screwing into the Crosshead

Locked in place

 I dropped the refinished piston into place, locked it down with a nut, and reattached the cylinder head.

Finished

 To keep compressed gas from leaking out of the cylinder and valve chest around the piston and valve rods, you have to install shaft packing. Shaft packing is a treated rope that is wound around the shaft and pressed into place to provide a tight seal. In this engine, the seal is pressed between screws with the shaft passing through them, and a threaded port in the cylinder or chest. The face of the screws and the bottom of the threaded port are tapered, so when the screw is tightened, the packing is pressed inward against the shaft. When installed correctly, very little gas can leak out.

The packing screws have been opened and cleaned.

Graphite-impregnated packing rope

Wrapped around the shaft...

...and pressed into place. The screw is then inserted and tightened to finish.

Same process for the piston rod.