Massachusetts Bay Transportation Authority 0622 and 0623 (Boston) at Seashore Trolley Museum
#0622 and #0623 are semi-permanently coupled together with cabs only at the outer ends of the two-car set. Some of the equipment needed to operate the two-car set is present only on one car of the pair, so that the cars can not be uncoupled and run individually. Conversely, one or two other two-car sets can be coupled to this set to form a four or six car train, with the motors and brakes of all cars under the control of the motorman in the front cab of the train.