The J.H. Paine Two-cylinder Inline Compound Steam Engine
The two pistons and valves of the J.H. Paine steam engine. Low pressure 14" piston and valve left, high pressure 7" piston and valve right. Fishermen’s Voice photo
The engine in the Sabino is the original 1908 J.H. Paine two-cylinder inline compound steam engine. There is a high-pressure cylinder 7" in diameter and a low-pressure cylinder 14" diameter. The current boiler is a 1947 replacement. There is no combustion in the engine and therefore no explosion that creates a shock wave as in a gasoline engine, therefore there is less wear on engine parts. A small amount of steam is allowed to leak over moving parts as an added lubricant.
The Paine engine is a reciprocating engine that gets maximum torque beginning at zero RPMs. The power is in the steam pressure in the boiler. When steam from the boiler is delivered to the cylinder it expands to produce 2500 foot pounds of torque immediately. An automobile gasoline engine must rev to 650 to 900 RPMs to inhale enough air to support the combustion process and deliver high levels of torque.
Original 1908 J.H. Paine steam engine during overhaul at Mystic Seaport, June 2015. Steam tank at top. Cylinders and pistons have been removed. Connecting rods and crankshaft at bottom. Fishermen’s Voice photo
The double-acting pistons in this steam engine get a power stroke from injected steam on both the down and the up strokes. In this continuous power-stroke engine, steam at 130 pounds per cubic inch is let into the smaller high-pressure cylinder through a valve. The steam expands and drives down the piston. At the bottom of the stroke steam from that smaller cylinder is then released through a valve to the larger low-pressure cylinder, expands again and drives the larger piston down. Simultaneously new steam is injected into the underside of the piston in the small cylinder driving it up, while the large cylinder piston is going down. The cycle begins again with steam let into the top of the smaller high-pressure cylinder.
Spent steam is not released to the atmosphere as in a railroad train steam engine. It is sent to a condenser to be liquified for reheating. The near-silent operation of this power plant is interrupted only by the light hiss of the lubricating steam leaking over moving parts.
J.H. Paine steam engine boiler. Fuel, coal in this case, is burned in the trough under the array of water pipes. Steam is sent to the two cylinder engine and spent condensed steam returned to the boiler. Fishermen’s Voice photo
Ed Crotty, the engineer at the Mystic Seaport shipyard, emphasized the “massive torque” output of the multiple-expansion steam engine. “The simplest example of a multiple expansion steam engine being the compound triple expansion steam engines on the Titanic. The Titanic had two 4-cylinder triple-expansion engines that were four stories high,” said Crotty. Hotter fluid produces more energy and these engines also exhausted into a low-pressure turbine which extracted another 6,000 HP for a total of 36,000 HP.
As for speed the first land speed record was for an electric car that went 60 MPH while the first gasoline cars were doing 16 MPH. The first land speed record was set by a steam-powered car in 1901 at 127 MPH. On the second run that car went airborne at an unofficial 170 MPH. Currently there is an engineering team at MIT in Cambridge, Mass., working on a steam-powered vehicle they hope will break the land speed record of 148 MPH for steam power.