EMD SW1500 Cows & Calfs                  

Here we are at the last first generation locomotives released by Atlas. Some may argue that they are really the beginning of the second generation of motive power because of the release date and the numbering series but I feel that, because they were manufactured by Rivarossi using their same basic motor, they belong with the first generation. As with the 0-4-0, the actual release date is a little fuzzy. Model Railroader stated, in the June 1970 issue "New Products" section, that  they "should be available at your hobby shop as you read this." However, it wasn't until March 1971 that Atlas was advertising them as "New for '71." I guess early 1971 would be about as close as one could get to pinpointing a date.

These were the last locomotives that Rivarossi would ever make for Atlas and Atlas would turn to Roco exclusively for what would be the second generation of motive power. Different versions of the Cow and Calf have been available through the years from other importers. Con-Cor released the same Rivarossi version after Atlas discontinued them and then a version using the Rivarossi shell but with a Kato mechanism. There was a re-release of them in 1997 just before Life-Like released their SW9/1200 series but a new Chinese mechanism was used. Rivarossi/Arnold currently sells them but with an unknown, to me, mechanism.

And, guess what? Through all of these years there is one thing about the shell that has never been corrected; the cab roof. It should be a smooth, rounded shape as on other SW switchers instead of three flat panels with the middle one being parallel to the ground and the other two sloping away. What happened was Rivarossi used a tentative drawing for a proposed SW1500 when they were working up the shell and EMD ended up releasing the SW1500 with a totally new body design. Hence there is a discrepancy in the designation of these units. Atlas advertised them as SW1500s but they are really a representation of the SW1200. In fact, the GM demonstrator version has TR12 imprinted on the sides which is EMD's designation for the SW1200.

Speaking of the prototype, the SW1200 was made for many years (1954-1966) and there were over a thousand built, making it one of EMD's most popular switchers. It is almost identical to the earlier SW7 and SW9 models, the only real spotting differences being louver placement and number. All three were 1200 horsepower units. Atlas offered them in Santa Fe, GM Demonstrator, Penn Central, Union Pacific, and Burlington roadnames and all of the railroads represented had SW1200s.

The Rivarossi model is a plastic shell and separate walkway molding over a zamac frame. There is an additional weight that fits into the cab portion of the shell. The same basic Rivarossi motor is used as in their other A1G locomotives but in a quite different configuration. In this case, the motor has a double-ended shaft with a worm on each end. Due to considerable space limitations in this small chassis, the worm diameters are much smaller than on the other Rivarossi A1G locos. The motor is kind of suspended under the zamac frame in an opening in the center with a spring sheet metal retainer that passes through holes in the top of the frame and snaps over the bushing extensions on the motor can and cap. The worms on the shaft then extend into openings in the bottom of the frame. The trucks are retained by plates mounted on the frame at each end with slots in them to engage bosses which extend from each side of the truck gearboxes. The left side plate at each end is insulated from the frame with a plastic spacer between it and the frame. A single screw through both plates and the frame hold them in place with an insulating washer on the left side.Wheel wipers are mounted on the gearboxes in the boss area and make contact with both the inner surface of each wheel and the retainer plates which gets current that far. Wires soldered to lugs under the plate mounting screws carry current to the motor brush holder on the left (hot) side and the right (ground) brush holder has a flat spring which contacts the motor can and the can is grounded through the motor retainer. Because the right side truck retainer plates are also grounded to the frame, this completes the circuit. In a departure from the past Rivarossi engines, there are no plastic traction tires used on this locomotive, Thus all eight wheels contribute to current collection with some sacrifice in pulling capacity.

Another couple of notes of interest: This is one of very few early N scale locomotives with the couplers mounted on the frame instead of the trucks (standard Rapido couplers, of course!). The headlight bulb is actually mounted at the rear of the frame in a plastic socket that fits between the two rear truck retainer plates and plastic pieces in the shell transmit the light to the front of the engine to the headlight. Kind of like fiber optics!

In spite of this locomotive design being eclipsed by later mechanisms, it was rather innovative for the time. Getting that motor and the rest of the drive into a chassis this small was undoubtedly a challenge.

Atlas identification: Unfortunately, I don't currently have any of these locomotives so I am unable to supply this information. Any help would be greatly appreciated

Variations: I haven't seen enough of these to determine any variations that may have occured. Any help would be greatly appreciated.

Please contact me with any additions or corrections: dgosha@aol.com

Links to images of the available liveries. Click on the description or thumbnail to view a full sized picture:

The images of the Santa Fe Cow and the Union Pacific Cow & Calf were kindly provided by Mark Peterson from his great Locomotive Encyclopedia site: http://www.visi.com/~spookshow/locos.html

The Burlington Cow image courtesy of Dave Alexander.

The GM Demo Cow and Calf images and the Santa Fe Calf image courtesy of Jim Starbuck.

Powered Cow Units:				Dummy calf Units:
#4001  Santa Fe		Road #2418		#4011  Santa Fe
#4002  GM Demo		"GM" (cab sides) "TR12" (front sides)		#4012  GM Demo
#4003  Penn Central				#4013  Penn Central
#4004  Union Pacific		Road #DS1870		#4014  Union Pacific
#4005  Burlington		Road #9280		#4015  Burlington

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