The Class J locomotives were the product of superior engineering and design, and resulted in performance unmatched in the era of steam or diesel.
Her restoration rekindles a bygone era of steam passenger rail and celebrates an extraordinary piece of American history, technology and craftsmanship. She provides powerful lessons in science, technology, history, engineering, design and art.
- The Class J locomotives are the most advanced and most powerful 4-8-4 steam passenger locomotive ever built in terms of actual drawbar horsepower at speeds up to 50 miles per hour.
- The Class J was designed for a maximum tractive effort of 80,000 pounds. Under controlled tests, an average drawbar horsepower of 5,028 was realized at a speed of 41.03 miles per hour. This performance has not been surpassed since.
- Under test conditions, the Class J locomotive propelled a 15-car, 1015-ton passenger train at 110 miles per hour on level tangent track. Performance in regular service was equally impressive, with speeds on straight sections of track reported to approach 100 miles per hour.
- The Class J was mounted on a rigid steel frame cast by General Steel Castings Corporation. This huge one-piece casting included not only the complete locomotive frame, but the two cylinders, the mounting brackets for certain auxiliaries and an extended support for the cab.
- Air compressors were mounted on the pilot beam area in front of the boiler. Hollow sections cast integral with the frame were designed to serve as reservoirs for compressed air used to operate the air brakes and signaling devices.
- The Class J was designed with comparatively small 70-inch drivers, allowing the riveted boiler to be unusually large in diameter with exceeding the clearance and height limits of eastern railways. The Class J had the longest combustion chamber of any 4-8-4 that burned bituminous coal.
- A unique side-rod-and-driver counter-balancing design permitted speeds in excess of 100 miles per hour with drivers only 70 inches in diameter. According to vibration calculations, the balancing theoretically would have allowed speeds of up to 140 miles per hour without rail damage.
- Timken Rolling Bearing Company designed the light-weight pistons, piston rods, crossheads and side-and-main-rod assemblies. Needle, roller and tapered-roller bearings were incorporated throughout the locomotive to reduce friction and wear.
- Mechanical pressurized lubrication systems could operate 1300 miles between refills, feeding oil to 220 points. Grease fittings were located to allow fast relubrication of 72 points.
