Sunday, November 4, 2007

What are all those cables?



Union Pacific, February 9, 1961, Argo Yard, Seattle. Okay, so you know an SD90MAC from a Dash 9-44CWL, and I don't. But now for all you "power users" it's time to really test your locomotive knowledge!

Can you itentify each connection shown here? Hint: 2 GP9B's.

The ability to run more than one railcar or locomotive by a single engineer from a single operating position solved a problem in the control of street cars and rapid transit cars, where trains were made up of individually self-powered cars, or a combination of self-powered and unpowered.

The problem involved not only the issue of transmitting control signals between cars, but also of making certain that the motors in all the cars operated in the same fashion and responded simultaneously to changes in the control signals issuing from the operator's position.

The system was pioneered by Frank Sprague and tested on the Chicago 'L' in 1897. Sprague's MU system was adopted for use by diesel-electric locomotives in the 1920s. These connections were entirely pneumatic. Todays modern MU control utilizes both pneumatic elements for brake control, and electric elements for throttle setting, dynamic braking and fault lights.
Most modern diesel locomotives are now delivered equipped for MU operation, allowing a consist (set) of locomotives to be operated from one cab, thereby eliminating the need for a train crew in each engine.
But, not all MU connections are standardised between manufacturers, limiting the types of locomotives that can be used together

MU systems can be easily spotted as large MU Cables to the right and left of the coupler. The connections typically consist of several air hoses for controlling the air brake system, and an electrical cable for the control of the traction equipment.
The largest hose, located next to the coupler is the main air brake line or "train line". Additional hoses link the air compressors on the locomotives and control the brakes on the locomotives independently of the rest of the train. There are sometimes additional hoses that control the application of sand to the rails.
Finally, locomotives set up to use "slugs" – units that have no diesel engine, just traction motors and ballast to insure tractive effort - have extra connections for transmitting electricity from the diesel electric generator on the "mother" unit to the traction motors on the slug.

1 Comments - Click here:

Dan said...

My small understanding:
There are at least 2 types of MU connections shown, not counting the hoses along the bottom. At some point, EMD changed its MU style, but locomotives were built using both styles, so as to have new units like the GP9s work well with older styles like F3s and FTs.
I know there is more to it than this, but its all I remember.

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