Coolspring Spotlight: 1917 600hp Snow

Author Photo
By Staff

This 1917 600hp Snow engine is a tandem, double-acting design, incorporating on a single crank throw two separate in-line (in tandem) cylinders.

At 75 feet long with an 18-ton, 18-foot-diameter flywheel, the 1917 600hp Snow is one of the largest gas engines ever to be preserved in running condition. The overall weight of the engine is estimated to be about 140 tons!

The Snow is housed in a building known as Exley Station, built in the fall of 2008 and named in memory of Clair Exley. Clair joined the museum staff and served six years on the Board of Directors. He loved the Snow as he remembered the Snow engines at Van, Pennsylvania, which he heard running during his childhood years. Retired from Joy Manufacturing Co. in Franklin, Pennsylvania, Clair was an excellent pipefitter. Unfortunately, his untimely passing prevented him from hearing this Snow run.

Thanks to the tireless efforts of many volunteers and generous contributions from many donors, the Snow engine achieved a very successful first run at about 10 p.m. on June 11, 2013. The museum officially dedicated the Snow engine exhibit on Oct. 18, 2013.

Prior to becoming a Worthington division, the Snow (later Snow-Holly) Steam Pump Works was organized in 1889 to build very large steam-powered pumping machinery. In 1898, it began building large gas-engine-driven natural-gas compressors, the first four being designed by National Transit’s chief engineer, John Klein.

Independently adjustable natural gas and air mixers. 

Richardson oilers lubricate the piston, piston rod packing case and exhaust valve stem. 



This Snow engine is a tandem, double-acting design, incorporating on a single crank throw two separate in-line (in tandem) cylinders. Each cylinder is double-acting, having two combustion chambers with one on each end of its symmetrical piston. Machined piston rods connect the two pistons and are sealed by “inverse piston rings” where they penetrate the four cylinder heads. Three external crossheads support the weight of the pistons and piston rods, and connect the reciprocating assembly to the single connecting rod.

A long side-shaft runs parallel to the cylinders. The intake and exhaust valves are located on the top and bottom, respectively, of each valve chest. The four fuel mixers are positioned between intake valve pairs and are individually adjustable to balance the power produced by each combustion chamber. Ignition is by dual low-tension igniters for added reliability.

An overhead tank supplies oil to all of the plain and reciprocating bearing surfaces. Used oil drains to a sump, from which it is pumped through a filter back to the overhead tank for reuse.

Original coil

On the end opposite the two power cylinders and connected to the main crosshead by two long tie-rods and a fourth crosshead, is the single 18-inch bore by 48-inch stroke natural-gas compressing cylinder. It is capable of discharging at a maximum of  600psi.

Chris Austin operates the 600hp Snow. 

The 18-foot-diameter flywheel is made in two halves and weighs 20 tons.


This engine operated from 1916 until 1992 at Pennsylvania Gas Co.’s (later, National Fuel Gas Supply Corp.’s) Roystone Station located near Sheffield, Pennsylvania.  During that time, it likely clocked hundreds of thousands of operating hours.

After being generously donated by National Fuel, a crew of museum volunteers descended on Roystone in the fall of 1993 to begin disassembly and removal to Coolspring. After a lengthy restoration and reassembly process that began in 2008, it first ran again at Coolspring in June 2013.


Learn about this engine and 38 others in Coolspring: Discovering America’s Finest Antique Engine Museum, Vol. 2. Order your copy at Gas Engine Magazine

Gas Engine Magazine

Preserving the History of Internal Combustion Engines