The Steamboating Forum

What are the oil cups on the cylinder heads for? And how do they work?

Without a picture it's tricky to be sure just what you mean, but probably what you see are sometimes called 'Tallow cups', That name comes from the days before commercially available, specially formulated, steam oils, when they used just that, tallow. They are used to introduce lubrication into the cylinder on a 'one shot' basis, i.e. at the start of the day, or even as required, but while the engine is stationary. The cup is filled, and with the piston at least part way down the cylinder, the tap is opened and the molten tallow/oil runs into the cylinder, and the tap is closed again.

We call them Fat Ladies I fill mine with steam oil and use it when I hear a squeak, and at the end of the day on shut down.

Doesn't the cylinder pressure push the oil out? Or does the engine have to be stopped? Where do I buy them?

As I said, "while the engine is stationary", therefore no pressure to push the oil out.

There are also ones with a chamber between two valves. Open top valve and fill the chamber, close top valve, open bottom valve and allow chamber contents to drain into cylinder, close bottom valve.

87gn@tahoe wrote:There are also ones with a chamber between two valves. Open top valve and fill the chamber, close top valve, open bottom valve and allow chamber contents to drain into cylinder, close bottom valve.

And usually with a pause to allow the heat transferred through the cylinder head to the holding chamber to fully melt the tallow into a nice slippery state for better lubrication.