| Chicago Transit Authority S-1 at the Des Plaines station (now the Blue Line) in Forest Park , Illinois on May 23, 1973, Ektachrome by Chuck Zeiler. I was the rear car of a fan trip (note photographers on the platform in the background) featuring S-1 Shhhicago, S-368, S-369, 4409 and 4410. Number S-1 was former 4358, converted to MOW service in May 1972. Abrasive stones were held in steel carriers supported by guides located between the wheels of one truck. Two air cylinders lowered the guide and maintained pressure to achieve contact while grinding. The grinding stones could be replaced manually from inside the car through an access hole cut into the floor of the car, covered by plexiglass. The S-1 was a control trailer, though rarely operated at the rear of the train. It was rebuilt again in 1976 to operated with 6000 series cab-signaled equipment. |