MR-73
The MR-73 is the second generation of rubber-tired rolling stock used on the Montreal Metro. Since the retirement of the first generation MR-63s, the MR-73 trains are in use on three of Montreal's four Metro lines.
Description
In the early 1970s, the Commission de transport de la Communauté urbaine de Montréal, the predecessor of the STM, identified a need for more rolling stock to serve the crowds expected for the 1976 Summer Olympics and for future network expansions. Although the design of what was to later become the MR-73 was completed in 1973, it was only in 1974 that the CTCUM formally awarded the MR-73 contract to the fledgling Bombardier Transportation. The 423 MR-73 cars were manufactured at Bombardier's La Pocatière plant between 1974 and 1980 and the first units entered service in 1976. The MR-73's original interior featured orange-and-white seats arranged so that in each third of the train, there were two double sets of transverse seating and four single seats near the doors in longitudinal formation, which were removed during the 2005-2008 refurbishments, and the seating arrangement was later modified.The MR-73 cars can be identified by rectangular cab headlights, side vents, blue and dark orange interiors, and traction motors that growl while accelerating, producing a unique three-note sound signature when the train pulls out of a station. The Mean Distance Between Failures for the MR-73 exceeds in 2004.
The initial rate of acceleration of the MR-73 model is . The three-note sound is produced by traction motor control equipment called a "current chopper", which controls and powers the motors on the train in stages without incurring a power surge. It does so by modulating the current in five consecutive stages, the last three being normally audible. A prototype for the current chopper was built by the Canron company using a Jeumont original design in the early 1970s on an MR-63 train. Two of the three elements of the "Jeumont Train" are operated on the Green Line among rheostatic-started MR-63s. One is much louder than the other. They are the only two to exhibit the whole five-note audible signature in normal operation even though it is possible to hear them during longer-than-usual starts on regular MR-73s.
The notes are the same as the first three notes of Aaron Copland's "Fanfare for the Common Man", one of the musical themes for Expo 67, but that is apparently just a coincidence. Some MR-73s originally sported murals of Montreal at the end of the cars; however, they were damaged by vandalism and removed long ago.
The MR-73 has a different electrical braking system from the MR-63 to assist friction braking. The MR-73's current chopper recuperates energy when in braking mode, turning traction motors into generators and sending a regulated current back into the traction power supply for other trains to use. Electrical braking is most effective when one train draws power while it is starting, and another train at a different location sends power while it is braking.
Lines serviced
Orange LineYellow Line
Blue Line
Formation
| Line # | Colour | Number of trains | Composition | Comments | - |
| 1 | 30 | + 78-xxx + + + 78-xxx + + + 78-xxx + | The MR-73 and MPM-10 Azur trains, replacing the aging MR-63s. | ||
| 4 | 5 | + 78-xxx + + + 78-xxx + Summer Break: + 78-xxx + + + 78-xxx + + + 78-xxx + | - | ||
| 5 | 18 | + 78-xxx + + + 78-xxx + | 3-car since 1986-2002 | - |