Union Pacific GTELs - Prototype

Prototype

Union Pacific had long sought the biggest and best locomotives available. In the 1930s a pair of steam turbine locomotives were tried but ultimately rejected. Even before World War II Union Pacific had been adding diesels to its roster, but these were mostly for passenger trains. The idea of lashing together four diesels to equal the power of a single steam locomotive was unappealing, so the search began for something bigger. General Electric had been building gas turbines for aircraft and proposed using something similar to create a more powerful locomotive. Union Pacific had discovered that the maintenance costs for a locomotive were largely independent of the locomotive's power output. Using a smaller number of more powerful locomotives would thereby save money.

Because a turbine's power output and fuel economy increase with speed, Union Pacific decided that the best way for the turbine locomotives to realize their potential would be to put them on mainline freight trains. The long uninterrupted runs and relatively high speeds would maximize the turbines' efficiency.

After Union Pacific expressed interest, Alco-GE built a prototype, GE 101, which was completed in November 1948. After tests in the Northeast during June 1949, it was renumbered UP 50. Painted in Union Pacific Armour Yellow, UP 50 began an extensive round of tests. Union Pacific never took ownership of this locomotive, however. This was one of the few internal combustion-powered locomotives used in North America that had a cab at each end. The cabs themselves resembled the FA units being built by Alco-GE at that time. The sides of the locomotive had numerous air intake louvers which could be opened and closed in varying patterns.

It was a carbody unit with a B+B-B+B wheel arrangement, i.e. four two-axle trucks, with pairs connected by span bolsters. The turbine produced 4,800 hp (3.6 MW), of which 4,500 hp (3.4 MW) was available for traction. This power output was more than double that of diesel-electric locomotives of that era.

For starting, the unit’s auxiliary diesel generator would be used to power a set of windings installed within the gas turbine’s main generator, causing the generator to rotate. The main generator’s rotation would begin to spin-up the turbine, at which point diesel fuel would be used to start combustion. A steam generator would also be used to heat and liquefy the turbine’s primary fuel supply (heavy "Bunker C" oil). When the turbine and fuel oil reached their minimum operating temperatures, the fuel feeding the turbine would be switched from diesel to the primary fuel.

This machine weighed 500,000 lb (230,000 kg) and was over 80 ft (24 m) long.

The turbines were delivered in three main groups after extensive testing of the prototype. Union Pacific intended to use the turbines to replace the famous Big Boys which were about to be retired at the time.