A Cornish engine in the USA
Now this series of posts on John West’s massive steam engine arrives at the point where it digs into the technical details. I have extracted various facts from the Damian Nance’s article, sifted, sorted and summarised to give a summary of the engine.
What was the President Engine?
The President was a rotative double acting engine with a 110″ cylinder, a 10 foot stroke and weight of 675 tons Although described as a Cornish engine, but had many features not common to pumping engines in Cornwall, i.e. it was rotative had flywheels, and was double acting.
The engine was named after president Ulysses S. Grant, who had been invited to its dedication but then failed to arrive.
Who built the engine?
The Cornish Engineer John West built the engine (the nephew of William West, the Last Great Cornish Engineer), and its components were built by various companies in Eastern USA. Merrick and sons built the engine at their Southwark factory Philadelphia, but much of the casting was done at Lazell Perkins and co Bridgewater Massachusetts. The Pumps, boilers and mountings were produced by LP Morris and co, Philadelphia.
What did the engine do?
The engine was built to pump large quantities of water from a relatively shallow mine shaft. Accounts of the engine differ in the number of pumps installed. Some state two pair, some three. Each pair of pumps consisted of a lifting pump at the bottom of the shaft, and a 30″ plunger pump part way up. The lifting pumps were only at a depth of 127 feet, very shallow compared to the Cornish mines of the time which were down to thousands of feet deep. The engine pumped at 15000 gallons per minute at 12 strokes per minute, and discharged into an adit and into a tank for use as boiler and condenser feed-water.
How was the steam provided?
An engine of this size demanded large quantities of steam, and so it had an impressive array of boilers. The President was served by 16 boilers in a boiler house to the rear of the engine house, each boiler was 50 feet long with a 36 inch diameter.
The engine was designed to run at 60 psi at which pressure it produced 3000 horsepower, although in use it was normally run at a lower pressure.
What was the key features of the President Engine?
Apart from its sheer size the President had several interesting features that set it apart from the standard arrangement of a pumping engine back in Cornwall. These differences arose from the shallow depth of the mine. Engines running expensively on the Cornish cycle are more effective if they have a load of the heavy pump rods in the shaft. To replace this John West designed the engine with large 92 ton flywheels of over 30 foot diameter. For smoother operation of the flywheel West made the engine double acting (powered on both up and down strokes).
Note: The weight and diameter of the flywheel has been shown differently on some engine descriptions. These figures have been confirmed as the most likely to be correct by Mark Connar, who I thank for the additional information.
Although he installed Cornish style steam valves, the operating method was unusual. Valve operation was through cams fitted on the flywheel shaft, three cams for three different values of cut-off. The throttle valve was fitted with an automatic control using a block of wood in the sump of the shaft connected by wire to the valve. An ingenious arrangement that allowed more steam to enter the engine as the water level rose.
The lattice beams
These are the features that attracted me to the engine. Although Open-work beams are graceful and light, they did not become widely adopted. Their main user was John West’s Uncle, William West of Tredenham. All of his most important engines used this design, and it is no doubt the family influence that resulted in their distinctive form being adopted for the President.
The story of William West is told in the Trevthick Society papaerback ‘The Last Great Cornish Engineer‘.