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Steam Locomotion in the 21st Century

The Recent History of Steam Locomotive Development


The ACE 3000

Drawings and Technical Specifications

Detail Views

Updated 12 February 2022

ACE 3000

ACE 3000 drawings by Don R. McCloskey

"Copyright 1982, MODEL RAILROADER Magazine, used by permission"

All back issues of Model Railroader including the June 1982 issue, which features the ACE 3000, can be accessed digitally via a subscription to Model Railroader.

Technical Specifications

Information compiled by the author from multiple articles and the ACE 3000 patent.

General Coal-fired, reciprocating drive steam locomotive. Consists of two sections: the Power Unit and the Support Unit. Overall length- 112 feet. Total weight- 650,000 lb. Meets AAR clearance/ overhang limits for unrestricted interchange (Plate B), and can negotiate 20 degree curves. Safety and Comfort Features Dual safety cabs permit clear view of track when traveling in either direction. 2.5 degree angle on cab front designed to deflect obstacles away from cab in the event of a collision. Computer readouts in cab permit monitoring of all engine functions. Air conditioning and toilets provided in each cab. Cabs removable from frame for easy repair.
Running gear 4-8-2 wheel arrangement. 4 cylinder, fully balanced "Withuhn" reciprocating compound drive. Inside connecting rods on quartered crank axles maintain high pressure and low pressure cylinders in synchronization for perfect balance and optimum steam flow for compound expansion. All welded frame construction, equipped with jacking pads to allow heavy maintenance on engine without an overhead crane. Cylinders 2 high pressure and 2 low pressure. All four cylinders mounted externally for ease of service and jacketed with saturated steam to maintain operating temperatures within required limits. Diesel-type replaceable sleeves and mutiple piston rings manufactured to diesel tolerances. Extended piston rods to prevent uneven cylinder/ring wear.
Condenser Twin eductor type, mounted in power unit. Steam exits low pressure cylinders, expands through low pressure turbine to provide power for stoker, feedwater pumps, and electrical generator. Condensing pressure 3 PSI absolute. Exhaust steam from turbine routed through eductor on power unit mixes with cool water (150 degrees F) from tender, mixing with it and condensing in a process similar to a steam injector. Hot discharge water (190 degrees F) from eductor routed to fan-cooled radiators on support unit. This process was expected to result in reduced condenser maintenance compared to the Henschel condensing system used on most previous condensing steam locomotives. 10,000 gallon storage tank in support unit allows 1000 miles between water stops at full power. Water is pre-treated before being pumped into tender or treated with on-board system to allow once-per-year boiler washes. Boiler Firetube type, Belpaire firebox, all-welded construction including welded stays, Porta Gas Producer Combustion System firebox, type "E" superheater, 300 PSIG operating pressure. Incorporates finned-tube economizer in smokebox. Boiler assembly designed for removal as a unit from the locomotive. Firebox designed to operate with a wide variety of low-sulphur coals. "Shuffle" grate provides continuous ash removal. Draft produced by steam powered fans. Cyclone separators remove fly-ash from exhaust upstream of fans. Combustion process in combination with use of low-sulphur coal and cyclone separators in exhaust path would allow engine to meet projected EPA air emission limits.
Bearings Timken AP roller type. Sealed to allow 250,000 miles between service with no additional lubrication. Axles, rods, and valve gear all equipped. Valve gear Walschaerts type. 15 inch diameter, 9 inch travel piston valves on all four cylinders; dual piston valves provided for each low pressure cylinder. Valves incorporate mutliple narrow sealing rings and saturated steam cooled liners for good lubrication and long life.
Fuel storage Coal stored on locomotive in three separate 11-ton capacity enclosed coal packs. Coal packs designed to be secured to flat cars for loading at mine with unprocessed, run-of-mine coal. Closure panels at top eliminate fugitive dust. Coal packs loaded onto locomotive using rubber-tired lift truck. Fuel capacity allows 500 mile range between fuel stops at full power. Gear-operated closure panels on bottom allow full coal packs to be installed and partially full coal packs to be removed without spilling coal. Panels and gearing designed to allow panel closure against blocking coal lumps without damage.
Ash handling Ash collected in 5 ton removable container pack on locomotive. Designed to be removed from locomotive using rubber-tired lift trucks and secured to flat car for shipment for bulk disposition. Alternatively, connections are provided to allow ash to be flushed out with water. Ash-handling technology adapted from new coal-fired ships constructed in the 1980's.
Drivers 54" diameter Scullin disk type. No separate tires (note- patent shows separate tires); designed for 250,000 mile wheel life. Low driver diameter allows optimum operating speed range with fully balanced running gear arrangement and maintains low chassis height to allow servicing using existing diesel facilities. Designed for truing using Hegenscheidt underfloor wheel lathe without removal from locomotive or removal of connecting rods. Controls Microprocessor-based. Completely automatic control of throttle, cutoff, and wheelslip control based on inputs from standard diesel-type 8 notch throttle and reverse lever. Coal feed and feedwater supply designed to be largely self-regulating by using engine feed steam or exhaust steam for power. Microprocessor system would provide minor "trim" adjustments for optimum operation. Electronic controls allow lead ACE 3000 to be "MU'ed" with other ACE's or diesels if the ACE is the lead engine. "Controlled slip" incorporated into drive logic, to allow maximum low-speed tractive effort to be developed. Fast-acting electronically actuated cylinder drain cocks provide nearly instant relief of cylinder pressure for control of undesirable wheel slip. "Dynamic braking" provided by proven counter-pressure brake principal, in which cylinders are used to provide engine braking.
Support Unit Dimensions Length- 57 feet. Total weight- 300,000 lb. Cooling capacity- 35 million BTUH. Power Unit Dimensions Length- 55 feet. Total weight- 350,000 lb. Weight on drivers- 240,000 lb.
Power 3000 DBHP nominal, 4000 DBHP at 20 to 80 MPH Thermal efficiency 15% overall typical, 18% peak
Tractive Effort 70,000 lbs at 0 to 15 MPH (continuous). Capable of attaining over 100,000 lb at starting with addition of positive displacement steam motors to support unit trucks. Servicing Features Sand, water, and lubricants can be supplied from ground level. Locomotive units sized to fit standard diesel shop pts.

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