The XD323 controller is one of a group of similar devices used on PCC cars and nicknamed "Washtubs" due to their shape. The XD323 was an early version used on air-electric cars. Every version of the Washtub was similar, with a pair of horseshoe shaped copper rings mounted on the inside edge of an insulating ring. Mounted to the inside of the ring are 99 moveable contacts, which are pressed against the ring by a pair of rollers, mounted on a rotation carrier. One mounting bolt for each finger extends outward from the ring, providing a point to which resistance ribbons are clamped. These are set up to create two rheostats, which operate in tandem. The rheostats are wired to give 75 steps of acceleration and 99 steps of dynamic braking. The carrier is driven by a pilot motor, and includes a drum with interlocks to operate field shunts and stop the motor at the end of its travel. Later versions include the XD373, XD423, and XD473.
Gerry. STM/BSRA
The next stop is Washington. Change for Forest Hills Trains on the Winter St. Platform, and Everett Trains on the Summer St. Platform. This is an Ashmont train, change for Braintree at Columbia.