UAC TurboTrain

The UAC TurboTrain was an early high-speed, gas turbine train manufactured by United Aircraft that operated in Canada between 1968 and 1982 and in the United States between 1968 and 1976. Amtrak disposed of the trains in 1980. It was one of the first gas turbine powered trains to enter service for passenger traffic, and was also one of the first tilting trains to enter service in North America.

Description

Chesapeake & Ohio design study

A series of design studies carried out by Chesapeake and Ohio Railway in the 1950s used the second-generation Talgo design for their car suspensions. The suspension arms for each neighboring pair of cars were attached to a common bogie ("truck") between them, as opposed to having a pair of separate bogies for each car. The bogies rode the common curve between the two cars, centered by traction springs that centered the axle between adjoining car bodies.
TurboTrain cars are lower than conventional cars, to lower the center of gravity in relation to the swinging point at the top of the arms. The arms included air springs to smooth out the motion, although it still felt "odd" while the train navigated short turns in switchyards and stations.

Like the earlier articulated trains, this meant that train lengths would be difficult to change. Their solution to this problem was to modify the power cars (engines) to allow the trains to be coupled end-to-end. Since articulated trains required "special" cars at either end anyway (to fill in the otherwise missing bogie), the C&O was double-ended, with a power car at each end. The power cars were organized with their two diesel engines on either side of the train, and the operators cabin in a "pod" on top. This left enough room for a passageway to run between the engines and under the pod to the nose of the car, where a coupling and doors were hidden behind a pair of movable clamshell covers. That way the train could be attached front-to-end with another, providing some of the flexibility in train lengths that coupled cars offered, while still being as lightweight as a normal articulated design.

TurboTrain

C&O's early work went undeveloped until the 1960s. At that time two major forces began operating that would re-invent the concept as the TurboTrain; one was the US Department of Transportation's desire to update train service in the US as a result of the High Speed Ground Transportation Act of 1965, the other was CN Rail's desire to update their passenger service with the ending of "pooled service" (with CP Rail) between Toronto and Montreal.

United Aircraft (UAC) purchased the C&O patents to enter into the DOT's Northeast Corridor Demonstration Project. The TurboTrain was designed by personnel of the Corporate Systems Center Division (CSC) of UAC, at Farmington, Connecticut. The design was similar to the original C&O version, but modified to use turbine power instead of diesel. The chosen engines were a modified version of the Pratt & Whitney Canada PT6 (also a UAC division) known as the ST6, downrated from . The PT6 uses a " free turbine" that acts as a torque coupler, so the new design did not require a transmission and was able to drive the powered wheels directly. The power cars had three engine bays on either side of the car and could mount engines in pairs for two to six turbines, depending on the needs of the carrier. Another ST6 drove an alternator to provide 'hotel' electrical power for the train. Each power car had a fuel capacity of .

The turbine engines were smaller and lighter ( with accessories) than the diesels they replaced, so the original power cars ended up being much larger than needed. Instead of a major redesign, UAC re-arranged the interior of the existing layout. The control room "pod" on top was lengthened to produce a viewing area with seating, and additional seating was added along the main level as well. This produced the Power Dome Cars (PDC) that were long (tip of nose to trailing articulated axle, while the Intermediate Cars (IC) were long (axle to axle), considerably shorter than the -long conventional passenger cars of this period.

The ability to connect trains together remained largely unchanged, although the routing of the internal passage changed slightly to rise up into the observation area of the pod, then back down under the control room and from there to the nose. This particular design, with the control cabs on top and couplers hidden behind doorways on the front, is similar to that of the NS Intercity Materieel used in the Netherlands.

The Turbotrains were evaluated by multiple journalists in the Canadian press as having "rail noise that substantially exceeds that of standard equipment" and having poor riding characteristics, especially on curves, with one journalist stating that "the single-axle articulation in practice negotiates curves in a series of short jerks rather than the smooth flowing motion promised in press releases".

The single-axle bogies on the Turbotrain were very mechanically complex and the suspension arms were "telescopic arms which were in essence ball-bearing screw actuators; the suspension of the inside-bearing powered bogies was "especially complex" and attached to the turbines via "an intricate web of mechanical couplings and shafts".

Production and use

U.S. service

Two Turbotrains (DOT1 and DOT2) were built at the Pullman Works in Chicago. High-speed testing of the trains was performed from a base at Fields Point in Providence, Rhode Island, using track between Route 128 near Boston and Westerly, Rhode Island (track segments along this section, to this day, are the only areas where Amtrak operates Acela revenue service at 150 mph).

After its construction at the Pullman yards in Chicago, the Turbotrain was sent eastward on August 1, 1967, at regular speed and without passengers, to Providence, Rhode Island in order for UAC Aircraft Systems engineers to tear it down, study it for further development, and then eventual high-speed testing on the PRR's specially-rebuilt track between Trenton and New Brunswick, New Jersey